UNIT 9

LEVEL OF STRUCTURAL

OUTLINE

Kingdom Plantae

OF PLANTS,

NATURAL HISTORY













9.1 PRINCIPLES AND METHODS OF TAXONOMY

SNAPSHOTS

Snapshot

1. Taxonomy (general), the practice and science (study) of classification of things or concepts, as well as the principles that underlie such a classification.

2. Taxonomy (biology), a field of science that encompasses the description, identification, nomenclature, and classification of organisms.

3. Biological classification, based on characteristics derived from shared descent from common ancestors.

4. Alpha taxonomy, the description and basic classification of new species, subspecies, and other taxa

5. Linnaean taxonomy, Carl von Linne's original classification scheme



Taxonomy is the academic discipline of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups.

Each group is given a rank and groups of a given rank can be aggregated to form a super group of higher rank and thus create a hierarchical classification.

The groups created through this process are referred to as taxa (singular taxon)

Biological taxonomy is a sub-discipline of biology, and is generally practiced by biologists known as "taxonomists", though enthusiastic naturalists are also frequently involved in the publication of new taxa. The work carried out by taxonomists is crucial for the understanding of biology in general.

Two fields of applied biology in which taxonomic work is of fundamental importance are the study of biodiversity and conservation.

Biodiversity is the degree of variation of life forms within a given species, ecosystem, biome, or planet. Terrestrial biodiversity tends to be highest at low latitudes near the equator, which seems to be the result of the warm climate and high primary productivity.

Marine biodiversity tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest and in mid-latitudinal band in all oceans.

The term biological diversity was used first by wildlife scientist and conservationist Raymond F. Dasmann in the 1968 lay book

Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions It is an interdisciplinary subject drawing on sciences, economics, and the practice of natural resource management

Conservation biology is tied closely to ecology in researching the dispersal, migration, demographics, effective population size, inbreeding depression, and minimum population viability of rare or endangered species.

Conservation biology is concerned with phenomena that affect the maintenance, loss, and restoration of biodiversity and the science of sustaining evolutionary processes that engender genetic, population, species, and ecosystem diversity.

Once a classification scheme is selected it’s used to arrange organisms into groups called as taxa based on mutual similarity.

Systematics is the process of organizing taxonomical information about organisms into logical classification that provides the framework for all comparative studies.

Systematics and taxonomy are collectively referred to as systematic biology.

Biological classification is a critical step in the taxonomic process, as it informs the user as to what the relatives of the taxon are hypothesized to be.

Although the discipline of taxonomy itself does not deal with the investigations of how taxa are related to one another, it does serve to communicate these results to the user. To do this, it uses taxonomic ranks, including, among others (in order from most inclusive to least inclusive): Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species.

Taxonomy has been called "the world's oldest profession" and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate.

9.1.1 ALPHA TAXONOMY

Alpha taxonomy is the discipline concerned with finding, describing and naming taxa (such as species) of living or fossil organisms.

For a long time the term "taxonomy" was used for what is today seen as alpha taxonomy. Over time, the term "taxonomy" has gained several other meanings and has thus become potentially confusing. To some extent it is being replaced, in its original (and narrow) meaning, by "alpha taxonomy".

As such, alpha taxonomy deals mostly with actual organisms and fossils: species and lower ranking taxa.

Higher ranking taxa (including clades and grades) mostly are the province of "beta taxonomy", more commonly called systematics.

9.1.2 EVOLUTIONARY TAXONOMY

Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship and degree of evolutionary changes. This type of taxonomy considers taxa rather than single species, so that groups of species give rise to new groups.

Evolutionary taxonomy arose as a result of the influence of the theory of evolution on Linnaean taxonomy. The idea of translating Linnaean taxonomy into a sort of dendrogram of the Animal and Plant Kingdoms was formulated toward the end of the 18th century.

As more and more fossil groups were found and recognized in the late 19th and early 20th century, paleontologists worked to understand the history of animals through the ages by linking together known groups, forming the tree of life. (The tree of life is a metaphor used to describe the relationships between organisms, both living and extinct)

Identification in biology is the process of assigning a pre-existing taxon name to an individual organism. Identification of organisms to individual scientific names (or codes) may be based on individualistic natural body features.

Identification methods may be manual or computerized and may involve using identification keys, browsing through fields guide that contain (often illustrated) species accounts, or comparing the organism with specimens from natural history collections.

9.1.3 CLASSIFICATION OF ORGANISMS

Classification is the process by which anything is grouped into convenient categories based on some easily observable characters. Biological classification is a critical step in the taxonomical process. Different methods have been used to classify organisms.

There are three basic methods used for the classification of organism:

PHENETICS

Phenetics also known as taximetrics, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation. It is closely

related to numerical taxonomy which is concerned with the use of numerical methods for taxonomic classification.

Phenetic techniques include various forms of clustering and ordination. These are sophisticated ways of reducing the variation displayed by organisms to a manageable level.

In practice this means measuring dozens of variables, and then presenting them as two or three dimensional graphs. Much of the technical challenge in phenetics revolves around balancing the loss of information in such a reduction against the ease of interpreting the resulting graphs.

PHYLOGENETIC

Phylogenetics is the study of evolutionary relationships among groups of organisms (e.g. species, populations), which are discovered through molecular sequencing data and morphological data matrices.

The result of phylogenetic studies is a hypothesis about the evolutionary history of taxonomic groups: their phylogeny.

Taxonomy, the classification, identification, and naming of organisms, is usually richly informed by phylogenetics, but remains methodologically and logically distinct.

The degree to which taxonomy depends on phylogenies differs between schools of taxonomy: numerical taxonomy ignored phylogeny altogether, trying to represent the similarity between organisms instead; phylogenetic systematics tries to reproduce phylogeny in its classification without loss of information; evolutionary taxonomy tries to find a compromise between them in order to represent stages of evolution.

Systems of classification:



The history of classification holds back to 2000 years ago with the work of Aristotle and his pupil who classified the entire living organisms into two broad classes the animal kingdom and the plant kingdom.

 Carolus Linnaeus also used the two kingdom classification and classified them into plants and animals based on their anatomical characteristics. distinguish between the eukaryotes and prokaryotes, unicellular and multicellular organisms and photosynthetic (green algae) and non-photosynthetic (fungi) organisms.



The three-domain system is a biological classification introduced by Carl Woese in 1977 that divides cellular life forms into archaea, bacteria, and eukaryote domains.

 Woese argued that, on the basis of differences in 16S rRNA genes, these two groups and the eukaryotes each arose separately from an ancestor with poorly developed genetic machinery, often called a progenote.



The three-domain system adds a level of classification (the domains) "above" the kingdoms present in the fiveclassification system recognizes the fundamental divide between the two prokaryotic groups, insofar as archaea appear to be more closely related to eukaryotes than they are to their fellow prokaryotic bacteria.



In 1806, Ernst Hackel proposed the three system of classification based on the work by Richard Owen and John Hogg. He classified them as

Kingdom Plantae

o Kingdom Animalia

o KingdomProtista (for single-celled eukaryotes)

With the discovery of electron microscope, 1938,

kingdom



Herbert F. Copeland proposed the four-kingdom classification moving bacteria into a separate kingdom

o Kingdom Plantae

o Kingdom Animalia

o Kingdom Protista

o Kingdom Monera (Prokaryotes, i.e. bacteria and blue-green algae)

The five-system classification was proposed by Robert H. Whittaker in 1969. The kingdom fundamentally split the prokaryotes from the eukaryotes. The kingdoms defined by him are:

o Kingdom Monera: Individuals are single-celled, may or may not move, have a cell wall, have no chloroplasts or other organelles, and have no nucleus. Monera are usually very tiny, although one type, namely the blue-green bacteria, look like algae. They are filamentous and quite long, green, but have no visible structure inside the cells. No visible feeding mechanism. They absorb nutrients through the cell wall or produce their own by photosynthesis

o Kingdom protista: Protists are single-celled and usually move by cilia, flagella, or by amoeboid mechanisms. There is usually no cell wall, although some forms may have a cell wall. They have organelles including a nucleus and may have chloroplasts, so some will be green and others won't be. They are small, although many are big enough to be recognized in a dissecting microscope or even with a magnifying glass. Nutrients are acquired by photosynthesis, ingestion of other organisms, or both.

o Kingdom fungi: Fungi are multicellular,with a cell wall, organelles including a nucleus, but no chloroplasts. They have no mechanisms for locomotion. Fungi range in size from microscopic to very large ( such as mushrooms). Nutrients are acquired by absorption. For the most part, fungi acquire nutrients from decaying material.

o Kingdom Plantae: Plants are multicellular and most don't move, although gametes of some plants move using cilia or flagella. Organelles including nucleus, chloroplasts are present, and cell walls are present. Nutrients are acquired by photosynthesis (they all require sunlight).

o Kingdom Animalia: Animals are multicellular, and move with the aid of cilia, flagella, or muscular organs based on contractile proteins. They have organelles including a nucleus, but no chloroplasts or cell walls. Animals acquire nutrients by ingestion

The main criteria used for classification by him include the cell structure, thallus organization, mode of nutrition, reproduction and phylogenetic relationship. (See table-

Characters

Celltype

Cellwall

Nuclear membrane

Body organization

Modeof nutrition

Autotrophic (chemosynthetic and photosynthetic) andHeterotrophic (saprophyte/ parasite)

9.1.1 Taxonomical Ranks:

Autotrophic (Photosynthetic) and Heterotrophic

Heterotrophic (Saprophytic/ Parasitic)

Autotrophic (Photosynthetic)

Heterotrophic (Holozoic/ Saprophytic Etc.)

Carolus Linnaeus in his book used a ranking scale limited to kingdom, class, order, genus, species, and one rank below species

The various units of classification are called taxonomical categories and together they make up the taxonomical hierarchy. Nomenclature is regulated by the nomenclature code which allows names divided into an infinite number of ranks. Every organism can be broadly classified into 7 levels:

In addition domain (proposed by ) is now widely used as one of the fundamental ranks.

 Using this we can classify human as: Domain-

9.1.2 Binomial nomenclature:



Linnaeus proposed a system of scientific naming using two names for every organism- the genus and the species.



The first word of the scientific name (species name) is the name of the genus to which the organism belongs. The second part of the name is the species.



The species name is usually a Latin description of some important characteristic of the organism.

 When we use the Latin name we always capitalize the genus name but not the species. We also print the name in italics or underline them.

 For example



A binomial scientific name in which the name of the genus and that of the species are identical is called tautonym.

Species are groups of interbreeding natural populations that are reproductively isolated from other such groups. Reproductively isolated means that members of the species do not interbred with members of other species.

Critical thinking Questions

1. Why is kingdom Monerano longer considered a valid taxon?

2. Why do some biologist describe the mitochondria of diplomonadsand parabasalids as ’highlyreduced’?

3. In what sense is ‘fungus animal’ a fitting description of a slime mold? In what senses is it not fitting?

9.2 LEVEL OF STRUCTURAL ORGANISATION

9.2.1 Unicellular Organisms:

A unicellular organism, also known as a single-celled organism, is an organism that consists of only one cell, unlike a multicellular organism that consists of multiple cells. Historically the simple single celled organisms have sometimes been referred to as monads.

The main groups of unicellular organisms are bacteria, archaea, protozoa, unicellular algae and unicellular fungi. Unicellular organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms.Unicellular organisms are the oldest form of life, they existed 3.8 billion years ago.

Prokaryotes, most protists, and some fungi are unicellular. Although some of these organisms live in colonies, they are still unicellular. These organisms live together, and each cell in the colony is the same. However, each cell must carry out all life processes in order for that cell to survive. In contrast, even the simplest multicellular organisms have cells that depend on each other in order to survive.

Some organisms are partially uni- and multicellular, like Dictyostelium discoideum. Other can be unicellular and multinucleate, like Myxogastria and Plasmodium.

‘Candidatus Magnetoglobus multicellularis’, related to Deltaproteobacteria, is a multicellular prokaryote. It is neither unicellular, nor a colony.

Most unicellular organisms are of microscopic size and are thus classified as microorganisms. However, some unicellular protists and bacteria are macroscopic and visible to the naked eye

Also known as single-celled organisms. As the name indicates they are made up of single cell. These organisms are very small and need to be seen with the help of microscope. Some examples of unicellular organisms include:

9.2.2 Colonial organisms:

A colony of single-celled organisms is called as colonial organisms.

The organisms within a particular community are often critically dependent upon one another for nutrients, more to the altered by their environment.

An example for colonial organisms can be a biofilm

9.2.3 Multicellular Organisms:

An organism made up of two or more cells. They can be easily visualized with the help of naked eyes. They can survive only when all the parts are present.

Multicellular organisms are organisms that consist of more than one cell, in contrast to single-celled organisms. To form a multicellular organism, these cells need to identify and attach to the other cells.

Only a dozen or so unicellular species have cells that can be seen individually with the naked eye. The rest of the nearly two million[citation needed] visible species are multicellular. In particular all species of

animals, land plants and filamentous fungi are multicellular, as are many algae. Some organisms are partially uni- and multicellular, like Dictyostelium.

9.2.4 Comparative Anatomy:

A comparative anatomical study of any particular organ system in the diverse members of a given phylum reveals a basic similarity of form which is varied to some extent from one class to another. It is closely related to evolutionary biology and phylogeny. Two major concepts of comparative anatomy

Homologous structures- It’s the similarity between various organs of different organisms and it is based on common embryonic origin or common ancestry. Homologous organs are those which have



the common origin and are built on the same fundamental pattern. For example, a whale’s or seal’s front flipper, a bat’s wing, a cat’s paw, a horse’s front leg, a human hand, etc.

Analogous structures- structures which are non-homologous but with similar functions are said to be analogous organs or structures. They have arisen in the evolutionary process through adaptations of quite different organisms to similar modes of life. The analogy, thus, refers to the relationship between structures which though differ anatomically but have superficial similarity due to similar functions.

Critical thinking Questions

While scientists universally believe that naturally occurring amino acids were mediated by nucleic acids to create the first life forms on Earth, the question of how nucleic acids originated from inanimate matter is still being studied today. There is no definitive answer yet as to the origin of life on Earth

Throughout history, two dominant theories of the origin of life on Earth have prevailed. Abiogenesis, a theory that is now widely discredited, holds that life was and is spontaneously generated from decaying organic matter. The theory of biogenesis, on the other hand, maintains that new life is produced from existing life forms

The oldest living things on Earth are believed to be single-cell prokaryotes, more commonly known as bacteria. Scientists have discovered fossils of such prokaryotes from roughly 3.5 billion years ago

9.3 OUTLINE CLASSIFICATION OF PLANTS, ANIMALS AND MICROORGANIMS Snapshot

1. Fossils and the comparative studies of living plants offer clues that the seed plants originated 360 million years ago.

2. Seed plants have a huge impact on human society. Humans started cultivating wheat, figs, maize, rice and other wild seed plants.

3. Mosses and other bryophytes have life-cycle dominated by gametophytes, whereas other seedless vascular plants have sporophytes-dominated life cycle.

4. Animals differ from both plants and fungi in their mode of nutrition. Plants are autotrophic eukaryotes capable of generating their organic molecules by the process of photosynthesis.

9.3.1 Kingdom Plantae

Kingdom plantae are multicellular eukaryotes with photosynthetic nutrition. Cells typically have cellulose wall, sap vacuole, plastids and several photosynthetic pigments.

It can be broadly divided into:

Figure 9. 5 Classification of plants

Plants appeared on land about 475 million years ago, and the evolutionary history of the plant kingdom reflects increasing adaptation to the terrestrial environment. The colonization of land by plants transformed the biosphere. This transformation created new adaptive zones and paved the way for other organisms.

Plants are multicellular eukaryotes that are photosynthetic autotrophs; however, not all organisms with these characteristics are plants. Plants share the following characteristics with their green algal ancestors:

Chloroplasts with the photosynthetic pigments: chlorophyll a, chlorophyll b, and carotenoids.

Cell walls containing cellulose

Food reserve that is starch stored in plastids.

It is the set of structural, chemical, and reproductive adaptations associated with terrestrial life that distinguishes plants from algae. Plants have evolved complex bodies with cell specialization for different functions.

Plants have developed structural specializations in order to extract the resources needed for photosynthesis (water, minerals, carbon dioxide, light) from the terrestrial environment (above and below ground).

In most plants, gas exchange occurs via stomata, special pores on the surfaces of leaves.

Chemical adaptation includes the secretion of a waxy cuticle, a coating on the surface of plants that helps prevent desiccation.

Cuticle waxes are secondary products, so named because they arise through metabolic pathways not common to all plants. (Cellulose is an example of a primary product).

Other secondary products include lignin (cell wall component of “woody” plants) and sporopollenin (a resilient polymer in the walls

9.3.1.1 PLANTS AS EMBRYOPHYTES

Gametes must be dispersed in a nonaquatic environment. Plants produce gametes within gametangia, organs with protective jackets of sterile (nonreproductive) cells that prevent gametes from drying out. he egg is fertilized within the female organ. Embryos must be protected against desiccation. The zygote develops into an embryo that is retained for awhile within the female gametangia's jacket of protective cells Emphasizing this terrestrial adaptation, plants are often referred to as embryophytes.

9.3.1.2 ORIGIN OF PLANTS

The green algae are likely the photosynthetic protists most closely related to plants. This conclusion is based on homologies in: cell wall composition and the structure and pigmentation of chloroplasts. Available evidence supports the hypothesis that plants and green algae called charophytes both evolved from a common ancestor.

Researchers have found the following homologies between charophytes and plants:

Green algae and plants both have the accessory pigments, chlorophyll b and beta-carotene.

Green algae and plants both have chloroplasts with thylakoid membranes stacked as grana.

Compared to chloroplast DNA of various green algae, plant chloroplast DNA most closely matches that of charophytes.

Most green algae and plants contain cellulose in their cell walls. Charophytes are the most plantlike in wall composition with cellulose making up 20% - 26% to 26% of the wall material.

Charophyte peroxisomes are the only algal peroxisomes with the same enzyme composition as plant peroxisomes.

Similarity in mitosis and cytokinesis. During cell division in charophytes and plants: The nuclear envelope completely disperses during late prophase. The mitotic spindle persists until cytokinesis begins. Cell plate formation during cytokinesis involves cooperation of microtubules, actin microfilaments, and vesicles.

Genetic relationship. DNA and rRNA similarities in charophytes and plants provides additional evidence for the hypothesis that charophytes are the closest relatives of plants.

Since alternation of generations does not occur among modern charophytes, it is presumed that alternation of generations in plants has had a separate origin from alternation of generations in other algal groups.

Its appearance in plants is thus analogous, not homologous, to the alternation of generations observed in various groups of algae.

In contrast to most algae, the parental thallus of Coleochaete retains the eggs, and after fertilization, the zygotes remain attached to the parent.

Nonreproductive cells of the thallus grow around each zygote, which enlarges, undergoes meiosis, and releases haploid swimming spores.



Haploid spores develop into new individuals.

The only diploid stage is the zygote; there is no alternation of multicellular diploid and haploid generations.

If an ancestral charophyte delayed meiosis until after the zygote divided mitotically, there would be a multicellular diploid generation (sporophyte) still attached to the haploid parent (gametophyte). Such a life cycle would be an alternation of generations.

If specialized gametophyte cells formed protective layers around a tiny sporophyte, this hypothetical ancestor would also be a primitive embryophyte.

Natural selection may have favored shallow-water plants tolerant to periodic drying. Adaptations to shallow water may also have been preadaptive for terrestrial life like waxy cuticle, protection of gametes, protection of developing embryos.

Eventually, accumulated adaptations made it possible for ancestral plants to live permanently above the water line, opening a new adaptive zone with: sunlight unfiltered by water and algae, soil rich in minerals and absence of terrestrial behavior.

9.3.1.3 Outline classification of plants

9.3.1.3.1 Thallophytes

The thallophytes are a polyphyletic group of non-mobile organisms traditionally described as "relatively simple plants" or "lower plants" with undifferentiated bodies (thalli). They were a defunct division of Kingdom Plantae, the Thallophyta (or Thallobionta) that included fungus and algae, and lichens occasionally bacteria and the Myxomycota.They have a hidden reproductive system and hence they are also called cryptogamae. Their general characteristics are as follows:

Algae are chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic (both fresh water and marine) organisms.

Habitat: largely aquatic (fresh water and marine), also occur in moist stones, soils and wood, also present in association with fungi (lichens) and animals.

Size and form of algae

Chlamydomonas, to colonial forms like A few of the marine forms such as kelps, form massive plant bodies.

Reproduction:

o Vegetative reproduction

o Asexual reproduction is by the production of different kinds of spores. Zoospores are flagellated and on germination give rise to new plants

o Sexual reproduction takes place through fusion of gametes. These gametes can be flagellated and similar in size or non-flagellated but similar in size. Such reproduction is called isogamous Fusion of two gametes dissimilar in size, as in some species of is termed as anisogamous. Fusion between one large, non-motile (static) female gamete and a smaller, motile male gamete is termed

They can be further classified as follows:

Chlorophceae

The members of chlorophyceae are commonly called green algae

The plant body may be unicellular, colonial or filamentous.

They are usually grass green due to the dominance of pigments chlorophyll a and b. The pigments are localized in definite chloroplasts.

The chloroplasts may be discoid, plate-like, reticulate, cup-shaped, spiral or ribbon-shaped in different species.

Most of the members have one or more storage bodies called pyrenoids located in the chloroplasts. Pyrenoids contain protein besides starch.

Some algae may store food in the form of oil droplets.

Green algae usually have a rigid cell wall made of an inner layer of cellulose and an outer layer of pectose.

Vegetative reproduction usually takes place by fragmentation or by formation of different types of spores.

Asexual reproduction is by flagellated zoospores produced in zoosporangia

The sexual reproduction shows considerable variation in the type and formation of sex cells and it may be isogamous, anisogamous and oogamous.

Some commonly found green algae are Chlamydomonas, Volvox, Ulothrix, Spirogyra and Chara

The members of phaeophyceae or

They show great variation in size and form.

They range from simple branched, filamentous forms ( ) to profusely branched forms as represented by kelps, which may reach a height of 100 meters.

They possess chlorophyll

They vary in color from olive green to various shades of brown depending upon the amount of the xanthophyll pigment, fucoxanthin present in them.

Food is stored as complex carbohydrates, which may be in the form of laminarin or mannitol.

The vegetative cells have a cellulosic wall usually covered on the outside by a gelatinous coating of

The protoplast contains, in addition to plastids, a centrally located vacuole and nucleus.

The plant body is usually attached to the substratum by a has a stalk, the

Vegetative reproduction takes place by fragmentation.

Asexual reproduction in most brown algae is by biflagellate zoospores that are pear-shaped and have two unequal laterally attached flagella.

Sexual reproduction may be isogamous, anisogamous or oogamous. Union of gametes takes place in water or within the oogonium.

Examples of Phaeophyceae -

Rhodophyceae

Rhodophyta are commonly called of the red pigment, r-phycoerythrin in their body.

Majority of the red algae are marine with greater concentrations found in the warmer areas.

They occur in both well-lighted regions close to the surface of water and also at great depths in oceans where relatively little light penetrates.

The red thalli of most of the red algae are multicellular. Some of them have complex body organization.

The food is stored as floridean starch which is very similar to amylopectin and glycogen in structure.

The red algae usually reproduce vegetatively by fragmentation. T

They reproduce asexually by non-motile spores and sexually by non-motile gametes.

Sexual reproduction is oogamous and accompanied by complex post fertilization developments.

The common members are: Polysiphonia, Porphyra), Gracilaria and Gelidium.

Uses of algae:

At least a half of the total carbon dioxide fixation on earth is carried out by algae through photosynthesis.



Being photosynthetic they increase the level of dissolved oxygen in their immediate environment. They are of paramount importance as primary producers of energy-rich compounds which form the basis of the food cycles of all aquatic animals.

Many species of Porphyra, Laminaria and Sargassum are among the 70 species of marine algae used as food. Certain marine brown and red algae produce large amounts of hydrocolloids (water holding substances), e.g., algin (brown algae) and carrageen (red algae) are used commercially. Agar, one of the commercial products obtained from Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies.

Chlorella and Spirullina are unicellular algae, rich in proteins and are used as food supplements even by space travelers

9.3.1.3.2 Bryophytes

Bryophyte is a traditional name used to refer to all embryophytes (land plants) that do not have true vascular tissue and are therefore called "non-vascular plants". Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be true vascular tissue Currently bryophytes are thought not to be a natural or monophyletic group; however the name is convenient and remains in use as a collective term for mosses, hornworts, and liverworts. Bryophytes produce enclosed reproductive structures (gametangia and sporangia), but they produce neither flowers nor seeds, reproducing via spores.

Bryophytes include the various mosses and liverworts that are found commonly growing in moist shaded areas in the hills.

Bryophytes are also called amphibians of the plant kingdom because these plants can live in soil but are dependent on water for sexual reproduction.

They usually occur in damp, humid and shaded localities.

Figure 9.10 Life cycle of a Byrophyte

They play an important role in plant succession on bare rocks/soil.

Bryophytes lack well-defined vascular tissues and lignified tissues. Organs such as leaves and roots of vascular plants are defined by the arrangement of their vascular tissue.

Bryophytes get their nutrition from dust, rainwater, and substances dissolved in water at the soil’s surface.

The main plant body of the bryophyte is haploid. It produces gametes, hence is called a gametophyte.

The sex organs in bryophytes are multicellular. The male sex organ is called antheridium. They produce biflagellate antherozoids.

The female sex organ called archegonium is flask-shaped and produces a single egg.

Zygotes do not undergo reduction division immediately. They produce a multicellular body called a sporophyte.

The sporophyte is not free-living but attached to the photosynthetic gametophyte and derives nourishment from it.

The bryophytes are divided into liverworts and mosses.

Figure 9.11 Liverworts: (a) female thallus; (b) male thallus

The liverworts grow usually in moist, shady habitats such as banks of streams, marshy ground, damp soil, and bark of trees and deep in the woods.

The plant body of a liverwort is thalloid, e.g., Marchantia. The thallus is dorsiventral and closely appressed to the substrate. The leafy members have tiny leaf-like appendages in two rows on the stem-like structures.

Asexual reproduction takes place by fragmentation of thalli or by the formation of specialized structures called gemmae. Gemmae are green, multicellular, asexual buds, which develop in small receptacles called gemma cups located on the thalli. The gemmae become detached from the parent body and germinate to form new individuals

Sexual reproduction: In Marchantia, its ribbon-like, dichotomously-branched gametophyte germinates from haploid spores. When male gametophytes mature, they produce small, umbrella-like structures called antheridiophores (means ‘antheridia-bearing’), which have numerous antheridia embedded along their dorsal surface. Female gametophytes produce (means ‘archegonia-bearing’) that resemble miniature palm trees. are formed on the ventral surface of the archegoniphore head (where the coconuts would be). Rain stimulates the antheridia to release sperm that make their way to a female gametophyte, up the archegoniophore stalk, and to the egg contained within the archegonium, where fertilization takes place and the zygote formed. Diploid sporophytes develop within swollen archegonia and sporangia are formed. Mature sporangia contain both spores (via meiosis) and elaters. As the elaters dry, they twist and disperse spores.

Mosses



The predominant stage of the life cycle of a moss is the gametophyte which consists of two stages.



The first stage is the stage, which develops directly from a spore. It is a creeping, green, branched and frequently filamentous stage.



The second stage is the , which develops from the secondary protonema as a lateral bud.

 They consist of upright, slender axes bearing spirally arranged leaves.



They are attached to the soil through multicellular and branched rhizoids. This stage bears the sex organs.

 Vegetative reproduction secondary protonema.

Sexual reproduction archegonia fertilizatio sporophyt loose-fitting hood called the the gametophyte. The sporophyt slender seta sporangium opening surrounded by and covered mature, the opercul outward produced as a result of meiosi stage and the cycle continues.

Uses of Bryophytes

Bryophytes in general are of little economic importance but some mosses provide food for herbaceous mammals, birds and other animals.

Species of Sphagnum, a moss, provide peat that has long been used as fuel, and because of their capacity to hold water as packing material for trans-shipment of living material.

along with lichens are the first organisms

decompose rocks making

colonies rocks and hence, are of great ecological

substrate

for the growth of higher plants.

9.3.1.3.3 Pteridophytes

The pteridophytes are vascular plants (plants with xylem and phloem) that produce neither flowers nor seeds, and are hence called vascular cryptogams. Instead, they reproduce and disperse only via spores. Pteridophytes include horsetails, ferns, club mosses, and quillworts. They are used for medicinal purposes, as soil -binders, and are frequently planted as ornamentals.

The sporophyte of seedless vascular plants, which dominates the life-cycle, is long-lived and often highly branched.

Pteridophytes are used for medicinal purposes and as soil-binders. They are also frequently grown as ornamental plants.

The pteridophytes are found in cool, damp, shady places though some may flourish well in sandy-soil conditions.

However, in pteridophytes, the main plant body is a sporophyte which is differentiated into true root, stem and leaves.

These organs possess welldifferentiated vascular tissues. The leaves in pteridophyta are small (microphylls) as in (macrophylls) as in ferns.

The sporophytes bear sporangia that are subtended by leaf-like appendages called some cases sporophylls may form distinct compact structures called strobili or cones ( Equisetum

The spores germinate to give rise to inconspicuous, small but multicellular, free-living, mostly photosynthetic thalloid gametophytes called prothallus

Sporophytes and gametophytes of seedless vascular plants are nutritionally independent of each other.

photosynthetic, and gametophytes are either photosynthesis or saprophytic (i.e. they obtain nutrition from dead and decaying organic matter).

Fern

Seedless vascular plants have a welldeveloped cuticle to minimize water loss. They also have stomata to allow gas exchange for photosynthesis.

Seedless vascular plants produce chlorophyll a and b, carotenoids, starch, cellulose cell wall and motile sperm.

In majority of the pteridophytes all the spores are of similar kinds; such plants are called homosporous

Figure 9.13 Selaginella

Genera like Selaginella and Salvinia which produce two kinds of spores, macro (large) and micro (small) spores are known as heterosporous. The megaspores and microspores germinate and give rise to female and male gametophytes, respectively.

The development of the zygotes into young embryos takes place within the female gametophytes. This event is a precursor to the seed habit considered an important step in evolution

Life cycle of a fern

Marsilea is excellent for observing a fern life cycle, because the male and female gametophytes have rapid development.

While still in the gelatinous mass, microspores break open, the male gametophyte germinates and matures, and within 24 hrs, sperm are released. sperm are cork-screwshaped with multiple flagellae.

Megaspores contain the female gametophyte, which is composed of a single, large cell and a small, multicellular archegonium.



The female gametophyte matures within 14 hrs, produces a chemical attractant for the sperm and fertilization normally occurs within 24 hrs.



The embryonic sporophyte is also fast developing and can usually be seen in approximately 2–3 days.

The pteridophytes are further classified into four classes:



Psilopsida- they are also known as Whisk fern. Psilophytes are and have a nutritionally independent, gametophyte prothallus that produces antheridia and archegonia. Sperm from the antheridia are released in wet habitats and make their way to the eggs, which are inside the archegonia. The diploid zygote develops into the sporophyte. E.g.



Lycopsida- There are only five genera of lycopods, three of which are common: Lycopodium and Seliginella

o Club mosses resemble over-sized mosses with an elongated cone at its apex. Lycopodium is homosporous and has a bisexual, prothallic gametophyte.

o Selaginella microspores have male gametophytes developing inside them, and the haploid megaspores contain the female gametophyte.

o Isoetes resemble porcupine quills and is commonly found on lake bottoms

Sphenopsida- Al Rushes. and steril narrow leav leaves chlorophyll. However, fertil with a sporangia-containing structure called a strobilus Equisetum shoots have silica deposits in their outer tissue for strength. Equisetum is homosporous and produces independent, prothallic gametophytes (either male or bisexual), about the size of a pinhead, on recently flooded soils. Bisexual gametophytes produce eggs and multiflagellated sperm from their respective archegonia and antheridia. Equisetum also reproduces asexually as shoots along an underground rhizome.

Pteropsida- They mainly contains ferns. Most ferns are homosporous and germinate heart-shaped, bisexual gametophytes, called prothalli. The aquatic fern, Marsilea, is heterosporous. Its sporophyte leaves have a long petiole attached to four floating leaflets, suggesting a floating four-leaf clover.

Figure9.15LifecycleofEquisetum

Vascular plants

The emergence of seed plants further transformed the Earth. Seeds and other adaptations of gymnosperms and angiosperms heightened the ability of plants to survive and reproduce in diverse terrestrial environments; these plants became the principal producers in the food webs of most ecosystems on land. Three life cycle modifications contributed to the success of terrestrial plants:

Reduction of the gametophyte. They were retained in the moist reproductive tissue of the sporophyte generation (not independent).

developed into embryos packaged with a food supply within a protective seed coat. Seeds replaced spores as main means of dispersal.

Evolution of pollen. Plants were no longer tied to water fo fertilization.

Seed development begins with a highly reduced female gametophyte contained within a megaspore, which is contained within a megasporangium

small opening called the become a protective seed coat after fertilization. The unfertilized megasorangium water as medium for bringing gametes together for fertilization, as with algae and seedless plants, seed plants use pollination to bring the sperm to the egg. Pollination employs wind, insects, birds, mammals, or sometimes water to carry pollen grains, which contain the male gametophyte, to the female gametophyte. The vascular plants can be further divided into two classes:

Figure 9.16 Structure of an ovule

the megaspore,



The gymnosperms ( ovules are not enclosed by any ovary wall and remain exposed, both before and after fertilization. The seeds that develop post-fertilization, are not covered, i.e., are naked.

 Gymnosperms include medium-sized trees or tall trees and shrubs. One of the gymnosperms, the giant redwood tree



The leaves in gymnosperms are well-adapted to withstand extremes of temperature, humidity and wind. In conifers, the needle-like leaves reduce the surface area. Their thick cuticle and sunken stomata also help to reduce water loss.



The gymnosperms are heterosporous; they produce haploid microspores and megaspores. The two kinds of spores are produced within sporangia that are borne on sporophylls which are arranged spirally along an axis to form lax or compact strobili or

The strobili bearing microsporophylls and microsporangia are called microsporangiate or male strobili. The microspores develop into a male gametophytic generation which is highly reduced and is confined to only a limited number of cells. This reduced gametophyte is called a pollen grain. The development of pollen grains takes place within the microsporangia.

The cones bearing megasporophylls with ovules or megasporangia are called macrosporangiate or female strobili. The male or female cones or strobili may be borne on the same tree (Pinus) or on different trees (Cycas).

The megaspore mother cell is differentiated from one of the cells of the nucellus. The nucellus is protected by envelopes and the composite structure is called an ovule

The ovules are borne on megasporophylls which may be clustered to form the female cones. The megaspore mother cell divides meiotically to form four megaspores. One of the megaspores enclosed within the megasporangium (nucellus) develops into a multicellular female gametophyte that bears two or more archegonia or female sex organs. The multicellular female gametophyte is also retained within megasporangium.

Life cycle of pine:

Microsporangia

male cones

megasporangia cones; both are in the same tree.

Male cones are small, fleshy, and ephemeral; while female cones are woody and may remain attached for several years.

Young microsporangia have numerous diploid, microspore mother cells and each undergoes meiosis to form haploid microspores

Each microspore develops into a pollen grain with two nuclei: a generative nucleus that gives rise to the sperm cells, and a tube nucleus that controls the pollen tube.

Each scale of the female come has two ovules, which are composed of a megasporangium surrounded by a thick integument.

Inside the megasporangium, a diploid megaspore mother cell undergoes meiosis to form four haploid megaspores, of which only one survives.

This remaining megaspore develops into the female gametophyte that bears two or three archegonia

Once the pollen grain has reached a female cone’s ovule, it takes approximately 1and 1/2 years for its pollen tube to reach the egg.

Inside the tube, the generative nucleus divides to form two sperm nuclei, only one of which fertilizes the egg, the other degenerates.

Figure 9. 20 Life cycle of an angiosperm

The fertilized ovule develops into two winged seeds, each of which is composed of an embryo, two embryonic leaves called cotyledons, an embyonic root, female gametophyte tissue that serves as reserve food, and a hard seed coat.

Angiosprerms

In angiosperms or flowering plants the pollen grains and ovules are developed in specialized structures called as flowers. In angiosperms seeds are enclosed by fruits.

They range in size from tiny, almost microscopic Wolfia to tall trees of Eucalyptus.

They provide us with food, fodder, feed and several other commercially important products.

They are divided into two classes: Dicotyledons and monocotyledons. The dicotyledons are characterized by two cotyledons in their seeds while the monocotyledons by one. The male sex organ in a flower is stamen.

Each stamen consists of a slender filament with an anther at the tip. The anthers following meiosis produce pollen grains. The female sex organ in the flower is the pistel or the carpel.

Pistel consists of an ovary enclosing one to many ovules. Within ovules are present highly reduced female gametophytes called as embryo sacs.

The embryo-sac formation is preceded by meiosis. Hence each of the cells in an embryo sac is haploid.

Each embryo sac has a three cells egg-apparatus- one egg cell and two synergids, three antipodal cells and two polar nuclei. The polar nuclei eventually fuse to form a secondary nucleus.

Pollen grains, after dispersal from the anthers, are carried by wind or various other agencies to the stigma of a pistil. This is termed as pollination. The pollen grain germination on the stigma and the resulting pollen tubes grow through the tissues of stigma and style and reach the ovule.

The pollen-tube enters the embryo sac where two male gametes are discharged. One of the male gamete fuses with the egg cell to form zygote (syngamy). The other male gamete fuses with the diploid secondary nucleus to form the triploid primary endosperm nucleus (PEN).

Because of the involvement of two fusions it is called as double fertilization, an event unique to angiosperm.

The zygote develops into an embryo with one or two cotyledons and the PEN develops into endosperm which provides the nourishment to the developing embryo.

The synergids and antipodals generate after fertilization. During this event the ovule develops into seed and the ovary into fruits.

9.3.2 Kingdom Animalia

In spite of difference of in form and structure of different animals, there are fundamental features common to various individuals in relation to arrangement of cell, body symmetry, number of coelum, pattern of digestive, circulatory or respiratory system. These features are used as the basis for classification of animals.

Level of organization:

Though all members of animalia are multicellular all of them do not exhibit the same pattern of organization of cells.

For example, in sponges the cells are arranged as loose aggregates. I.e. they exhibit cellular level of organization.

Figure 9. 21 Radial

Figure 9.22 Bilateral symmetry

In coelenterates, the arrangement of cell is more complex. Here the cells performing the same function are arranged into tissues, hence called as tissue level of organization.

A still higher level of organization, i.e. organ level is exhibited by members of Platyhelminthes and other higher phyla where tissues are grouped together to form organs, each specialized for a particular function.

In animals like Annelids, Arthropods, Molluscs, Echinoderms and Chordates, organs have associated to form functional systems, each system concerned with a specific physiological function. This system is called organ system level of organization. Organ system in different groups of animal’s exhibit different pattern of complexities.

For example, the digestive system in Platyhelminthes has only one opening to the outside of the body that serves as both mouth and anus and hence is called incomplete. A complete digestive system has two openings, the mouth and the anus.

the circulatory system may be of two types:

Open type in which the blood is pumped out of the heart and the cells or tissues are directly bathed in it.

Closed type in which the blood is circulated through a series of vessels of varying diameter Symmetry

Animals are categorized on the basis of their symmetry.

Sponges are mostly asymmetric i.e. any plane that passes through the center does not divide them into two equal halves. When any plane passing through the central axis of the body divides the organism into two identical halves, it is called as and ectinoderms,

When the body can be divided into identical left and right halves in only one plane, its called as bileteral symmetry, Eg, Annelids, anthropods, etc.

Diplobalstic and Triblastic organisation:

Animals in which cells are arranged in two embryonic layers, and external ectoderm and an internal endodermb are called as diploblastic organisms. An undiffernetiated mesoderm is present in between the ectoderm and endoderm called as mesoglia.

Those animals in which the developing embryo has a third germinal layer, mesoderm in betwee n the ectoderm and endoderm is called as triploblastic organism. (platyhelminthes to cordata).

Coelom:The body cavity which is limed by mesoderm is called as coelom. Animals possesing coelom are called as coelomates, eg, annelid, molluscs, anthropods, echinoderms, hemicordata and cordata.

In some animals the body cavity is not lined by mesoderm, instead, the mesoderm is present as scattered pouches between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and animals possesing them are called as pseudocoelomates, eg, aschelminthes The animals in which the body cavity is absent are called as acoelomates, eg., platyhelminthes.

Classification of Animals:

Broad classification of Kingdom Animalia based on fundamental features are given as shown below:

Phylum- Porifera:

Members of this phylum are commonly known as sponges. They are generally marine and mostly asymmetrical animals.

They are primitive multicellular organisms and have cellular level of organization.

Sponges have water transport or canal system. Water enters through minute pores (ostia) in the body wall into a central cavity, spongocoel, from where it goes out through the osculum. This pathway of water transport is helpful in food gathering, respiratory exchange and removal of waste. Choanocytes or collar cells line the spongocoel and the canals.

Digestion is intracellular. The body is supported by a skeleton made up of spicules or sponging fibers.

Sexes are not separate (hermaphrodite) i.e., egg and sperm are produced by the same individual.

Sponges reproduce asexually by fragmentation and sexually by formation of gametes.

Fertilization is internal and development is indirect having a larval stage which is morphologically distinct from the adult.

Example: Sycon (Scypha), Spongilla (Fresh water sponges) and Euspongia (Bath sponge)

Phylum –Coelenterata (Cnidaria)

They are aquatic, mostly marine, sessile or freeswimming, radially symmetric animals.

The name cnidaria is derived from cnidoblasts or cnidocytes (which contain the stinging capsules or nematocyetes) present on the tentacles or the body.

Cnidoblast is used for anchorage, defense and for the capture of prey.

Cnidarians exhibit tissue level of organization and are diploblastic.

They have a single gastro-vascular cavity with a single opening, hypostome.

Digestion is extracellular and intracellular.

Some of the cnidarians, e.g., corals have a skeleton composed of calcium carbonate. Cnidarian and medusa. The former i the latter is umbrella-shaped an

Those cnidarians which exist in both forms exhibit alternation of generation (Metagenesis) i.e. polyps form medusa asexually and medusa form polyp sexually. (E.g. Obelia).

Example: Physalia (Portuguese man-of-war); Adams is (Sea anemone); Panatela (Sea-pen)

Phylum- Ctenophora

Commonly known as sea walnuts or comb jellies are exclusively marine, radially symmetric, diploblastic organisms with tissue level of organization.

The body bears eight external rows of ciliated comb plates, which help in locomotion.

Digestion is both extracellular and intracellular.

Bioluminescence is well marked in ctinophores. Sexes are not separate.

Figure 9. 27 Pleurobrachia

Reproduction only takes place by sexual means. Fertilization is external with indirect development. Example; Pleurobrachia, Ctenoplana.

Phylum- Platyhelminthes.

They have dorso-ventrally flattened body, hence are called flatworms.

They are mostly endoparasites found in animals including humans.

Flatworms are bilaterally symmetric, triploblastic and acoelomate animals with organ level of organization.

Hooks and suckers are present in the parasite forms.

Some of them absorb nutrients from the host directly through their body surface.

Specialized cells called flame cells help in osmoregulation and excretion.

Sexes are not separate. Fertilization is internal and development is through many larval stages. Some members like Planaria possess high regeneration capacity.

Example, Taenia (Tapeworm), Fasciola (Liver fluke)

Phylum-Aschelminthes

The body of aschelminthes is circular in cross-section, hence, the name roundworms.

They may be free-living, aquatic, terrestrial or parasitic in plants and animals.

Roundworms have organ system level of organization. They are bilaterally symmetric, triploblastic and pseudocoelomate animals.

Alimentary canal is complete with a well developed muscular pharynx. An excretory tube removes body wastes from the body cavity through the excretory pore.

Sexes are separate (diecious), i.e., males and females are distinct. Often females are longer than males. Fertilization is internal and development may be direct or indirect.

Example: Ascaris (round worm) Wuchereria (Filaria worm) Ancylostoma (hookworm)

Phylum- Annelida

They may be aquatic (marine and fresh water) or terrestrial; free-living and sometimes parasitic. They exhibit organ-system level of organization and bilateral symmetry. They are triploblastic, metamerically segmented and coelomate animals. Their body is distinctly marked into segments or metameres. And hence the phylum name Annelida.

They possess longitudinal and circular muscles which help in locomotion. Aquatic annelids like Nerris possess lateral appendages, parapodia, which help in swimming.

A closed circulatory system is present. Nephridia help in osmoregulation and excretion. Neural system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord.

Nereis, an aquatic form, is dioecious, but earthworms and leeches are monoecious.

Reproduction is sexual.

Example: Nerris, Pheretime (Earthworm) and Hirudinaria (blood sucking leech)

Phylum- Arthropoda

This is the largest phylum of Animalia which includes insects.

Figure 9.28 a) Taenia;

Figure 9.29 Aschelmintes

Figure 9. 30 a) Nerris; b)Hirudinaria

They have organ-system level of organization. They are bilaterally symmetric, triploblastic, segmented and coelomate animals.

The body of arthropods is covered with chitinous exoskeleton. The body consists of head, thorax and abdomen. They have joint appendages.

Organs are gills, book-gills, book lungs or tracheal system.

Circulatory system is of open type. Sensory organs like antennae, eye (compound eye), ststocysts or balance organs are present. Excretion takes place through malphigian tubules.

Are mostly dioecious. Fertilization is usually internal. Development may be direct or indirect. Examples: Apics (Honey bee) Bombyx mori (Silk worm), locusta, Aedes (mosquito)

Phylum- Mollusca

This is the second largest animal phylum. Mollusca are terrestrial or aquatic (marine or fresh water) having an organ-system level of organization.

They are bilaterally symmetric, triploblastic and coelomate animals.

Body is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot and visceral hump.

The space between the hump and the mantle is called the mantle cavity in which feature like gills are present.

They have respiratory and excretory functions. The anterior head region has sensory tentacles. The mouth contains a file-like rasping organ for feeding, called radula.

They are usually dioedious and oviparous with indirect development. Example: Pila (Apple snail),

Phylum- Echinodermata

These animals have an exoskeleton of calcareous ossicles and, hence, the name Echinodermata.

All are marine with organ-system level of organization. The adult echinoderma are radially symmetric but the larvae are bilaterally symmetric. They are triploblastic and coelomate animals. Digestive system in complete and mouth on the lower (ventral) side and anus on the upper (dorsal) side. The most distinct feature of echinoderms is the presence of water vascular system which helps in locomotion, capture, transport of food and respiration.

excretory system is absent. Sexes are separate. Reproduction is sexual.

Fertilization is external. Development is indirect with free-swimming larva.

Example: Asterias (Star fish), Echinus (Sea urchin),

Cucumaria (sea cucumber)

Phylum- Hemichordata

Hemichordata was earlier considered as sub-phylum under phylum chordata.

This phylum consists of small group of worm-like marie animals with organ-system level of organization.

They are bilaterally symmetric, triploblastic and coelomate animals.

Their body is cylindrical and is composed of an anterior proboscis., a collar and a long trunk. Circulatory system is of open type. Respiration takes place through gills. Excretory system is proboscis gland.

Sexes are separate. Fertilization is external. Development is indirect.

Example: Balanoglossus and Saccoglossus

Phylum- Chordata

Figure 9.31 a) Scorpio; b)Prawns

Figure 9.32 a) Pila b)Octopus

Figure 9.33 a) Asterias;

Figure9.34 Balanoglossus

Animals of this phylum are fundamentally

They

bilaterally

a closed circulatory system.

by

presence of a notochord, a dorsal hollow nerve cord and pharyngeal

a post anal

Phylum chordata is subdivided into three subphyla: unichordata, cephalochordate, vertebrata.

Subphyla Urochordata and Cephalochordata are referred to as protochordates and are exclusively marine.

In urochordata notochord is present only in larval tail while in cephalochordata , it extends from head to tail region and is persistent throughout their life.

Example: Urochordata- Ascidia, Salpa; Cephalochordata- Branchiostoma.

The members of the subphylum vertebrata possess notochord during the embryonic period

The notochord is replaced by a cartilaginous or bony vertebral column in the adult.

Thus all vertebrates are chordate but all chordates are not vertebrates.

The vertebrates have a ventral muscular heart with two, three or four chambers.

Kidneys for excretion and osmoregulation and paired appendages which may be fins or limbs.

The subphylum vertebrata is further divided as:

9.36

Table:

Amphibia

Transition from aquatic to terrestrial, different body forms, forelimbs of frog are smaller than hind limbs, webbedfeet, surfaceof skinissmoothandslimy due to mucous, scales absent, external nostrils, heart three-chambered, respiration by gills, lungs skin and pharyngeal region, skeleton bony, fertilization external orinternal,sexesseparate.

Examples

Frog, Toad, Salamander,Caecilian

Aves

9.3.3 Microbial taxonomy

One of the most fascinating and attractive aspects of the microbial world is its extraordinary diversity. Because of the bewildering diversity of living organisms, it is desirable to classify or arrange them into groups based on their mutual similarity.

Microbial Evolution and Diversity:

It has been estimated that our planet is about 4.6 billion years old. Fossilized remains of prokaryotic cells around 3.5 to 3.8 billion years old have been discovered in stromatolites and sedimentary rocks. Stromatolites are layered or stratified rocks, often domed, that are formed by incorporation of mineral sediments into microbial mats. Modern stromatolites are formed by cyanobacteria; presumably at least some fossilized stromatolites were formed in the same way. Thus prokaryotic life arose very shortly after the earth cooled. Very

likely the earliest prokaryotes were anaerobic. Cyanobacteria and oxygen-producing photosynthesis probably developed 2.5 to 3.0 billion or more years ago. Microbial diversity increased greatly as oxygen became more plentiful.

Phylogenetic tree:

Phylogenetic relationships are illustrated in the form of branched diagrams or trees

A phylogenetic tree is a graph made of branches that connect nodes. The nodes represent taxonomic units such as species or genes; the external nodes, those at the end of the branches, represent living organisms.

The tree may have a time scale, or the length of the branches may represent the number of molecular changes that have taken place between the two nodes. Finally, a tree may be unrooted or rooted.

An unrooted tree simply represents phylogenetic relationships but does not provide an evolutionary path. In contrast, the does give a node that serves as the common ancestor and shows the development of the four species from this root. The tree is divided into three major branches representing the three primary groups: Bacteria, Archaea, and Eucarya.

The archaea and bacteria first diverged, and then the eukaryotes developed. These three primary groups are called and placed above the phylum and kingdom levels. The domains differ markedly from one another.

Eukaryotic organisms with primarily glycerol fatty acyl diester membrane lipids and eukaryotic rRNA belong to the Eucarya. contains prokaryotic cells with bacterial rRNA and membrane lipids that are primarily diacyl glycerol diesters. Prokaryotes having isoprenoid glycerol diether or diglycerol tetraether lipids in their membranes and archaeal rRNA compose the third domain,

9.3.3.1 Systems of classification:

Phenetic Classification

Groups organisms together based on the mutual similarity of their phenotypic characteristics.

Are not dependent on phylogenetic analysis.

They compare many traits without assuming that any features are more phylogenetically important than others.

Organisms sharing many characteristics make up a single group or taxon.

Numerical Taxonomy

It is the quantitative approach of

Peter H. A. Sneath and Robert Sokal have defined numerical taxonomy as "the grouping by numerical methods of taxonomic units into taxa on the basis of their character states."

Information about the properties of organisms is converted into a form suitable for numerical analysis and then compared by means of a computer. The resulting classification is based on general similarity as judged by comparison of many characteristics, each given equal weight.

The process begins with a determination of the presence or absence of selected characters in the group of organisms under study.

A character usually is defined as an attribute about which a single statement can be made. Many characters, at least 50 and preferably several hundred, should be compared which must include many different kinds of data: morphological, biochemical, and physiological.

After character analysis, an association coefficient, a function that measures the agreement between characters possessed by two organisms, is calculated for each pair of organisms in the group.

The simple matching coefficient ( S SM ) , the most commonly used coefficient in bacteriology, is the proportion of characters that match regardless of whether the attribute is present or absent.

Sometimes the Jaccard coefficient ( S J ) is calculated by ignoring any characters that both organisms Lack.

Both coefficients increase linearly in value from 0.0 (no matches) to 1.0 (100% matches).

The simple matching coefficients, or other association coefficients, are then arranged to form a similarity matrix. This is a matrix in which the rows and columns represent organisms, and each value is an association coefficient measuring the similarity of two different organisms so that each organism is compared to every other one in the table.

Organisms with great similarity are grouped together and separated from dissimilar organisms; such groups of organisms are called phenons (sometimes called phenoms).

The results of numerical taxonomic analysis are often summarized with a treelike diagram called a dendrogram

The diagram usually is placed on its side with the X-axis or abscissa graduated in units of similarity. Each branch point is at the similarity value relating the two branches.

The organisms in the two branches share so many characteristics that the two groups are seen to be separate only after examination of association coefficients greater than the magnitude of the branch point value. Below the branch point value, the two groups appear to be one. The ordinate in such a dendrogram has no special significance, and the clusters may be arranged in any convenient order.

Phylogenetic Classification

These are systems based on evolutionary relationships rather than general resemblance (the term phylogeny generation or origin] refers to the evolutionary development of a species).

The direct comparison of genetic material and gene products such as RNA and proteins overcomes many of these problems.

9.3.3.2 Major Characteristics Used in Taxonomy

Classical Characteristics: Classical approaches to taxonomy make use of morphological, physiological, biochemical, ecological, and genetic characteristics. These characteristics have been employed in microbial taxonomy

Morphological Characteristics: Morphology is easy to study and analyze, particularly in eukaryotic microorganisms and the more complex prokaryotes. In addition, morphological comparisons are valuable because structural features depend on the expression of many genes, are usually genetically stable, and normally (at least in eukaryotes) these do not vary greatly with environmental changes.

Physiological and Metabolic Characteristics: Physiological and metabolic characteristics are directly related to the nature and activity of microbial enzymes and transport proteins. Since proteins are gene products, analysis of these characteristics provides an indirect comparison of microbial genomes.

Ecological Characteristics: Many properties are ecological in nature since they affect the relation of microorganisms to their environment. Microorganisms can differ considerably with respect to ecological characteristics. Some examples of taxonomically important ecological properties are life cycle patterns; the nature of symbiotic relationships; the ability to cause disease in a particular host; and habitat preferences such as requirements for temperature, pH, oxygen, and osmotic concentration.

Genetic Analysis: Although prokaryotes do not reproduce sexually, the study of chromosomal gene exchange through transformation and conjugation is sometimes useful in their classification. Transformation can occur between different prokaryotic species but only rarely between genera. Conjugation studies also yield taxonomically useful data, particularly with the enteric bacteria

Molecular Characteristics: Because these are either direct gene products or the genes themselves, comparisons of proteins and nucleic acids yield considerable information about true relatedness. These more recent molecular approaches have become increasingly important in prokaryotic taxonomy.

Comparison of Proteins: The amino acid sequences of proteins are direct reflections of mRNA sequences and therefore closely related to the structures of the genes coding for their synthesis. There are several ways to compare proteins. The most direct approach is to determine the amino acid sequence of proteins with the same function. The sequences of proteins with dissimilar functions often change at different rates; some sequences change quite rapidly, whereas others are very stable. Nevertheless, if the sequences of proteins with the same function are similar, the organisms



possessing them are probably closely related. Because protein sequencing is slow and expensive, more indirect methods of comparing proteins frequently have been employed. The electrophoretic mobility of proteins is useful in studying relationships at the species and subspecies levels. Antibodies can discriminate between very similar proteins, and immunologic techniques are used to compare proteins from different microorganisms. The physical, kinetic, and regulatory properties of enzymes have been employed in taxonomic studies. Because enzyme behavior reflects amino acid sequence, this approach is useful in studying some microbial groups, and group-specific patterns of regulation have been found.

Nucleic Acid Base Composition: Microbial genomes can be directly compared, and taxonomic similarity can be estimated in many ways

o The first, and possibly the simplest, technique to be employed is the determination of DNA base the percent of hydrolysis of DNA and analysis of its bases with high-performance liquid chromatography (HPLC). The G + C content

o In double-stranded DNA three hydrogen bonds join GC base pairs, and two bonds connect AT base pairs. As a result DNA with a greater G + C content will have more hydrogen bonds, and its strands will separate only at higher temperatures-that is, it will have higher melting point.

o DNA melting can be easily followed spectrophotometrically because the absorbance of 260 nm UV light by DNA increases during strand separation. When a DNA sample is slowly heated, the absorbance increases as hydrogen bonds are broken and reaches a plateau when the entire

o The midpoint of the rising curve gives the melting temperature, a direct measure of the G + C content. Since the density of DNA also increases linearly with G + C content, the percent G + C

o If two organisms differ in their G + C content by more than about 10%, their genomes have quite different base sequences. On the other hand, it is not safe to assume that organisms with very similar G + C contents also have similar DNA base sequences because two very different base

o Only if two microorganisms also are alike phenotypically do their similar G + C content suggest

o G + C content data are taxonomically valuable in at least two ways. First, they can confirm a taxonomic scheme developed using other data. If organisms in the same taxon are too dissimilar in G + C content, the taxon probably should be divided. Second, G + C content appears to be useful in characterizing prokaryotic genera since the variation within a genus is

o Micrococcus DNA has 64 to 75% G + C; yet these two genera of gram-positive cocci have many other features in



Nucleic Acid Hybridization:

o nucleic acid studies. If a mixture of single-stranded DNA formed by heating dsDNA is cooled , strands with complementary basesequences will reassociate to form stable dsDNA, whereas non-complementary strands will remain single.

o Because strands with similar, but not identical, sequences associate to form less temperature stable dsDNA hybrids, incubation of the mixture at 30 to 50°C below the T m will allow hybrids of more diverse sedans to form.

o Incubation at 10 to 15°C below the T m permits hybrid formation only with almost identical strands. Two strains whose DNAs show at least 70% relatedness under optimal hybridization conditions and less than a 5% difference in T m often are considered members of the same species.

o If DNA molecules are very different in sequence, they will not form a stable, detectable hybrid. Therefore DNA-DNA hybridization is used to study only closely related microorganisms. More

distantly related organisms are compared by carrying out DNA-RNA hybridization experiments using radioactive ribosomal or transfer RNA.

o Distant relationships can be detected because rRNA and tRNA genes represent only a small portion of the total DNA genome and have not evolved as rapidly as most other microbial genes.

Nucleic Acid Sequencing

o Despite the usefulness of G-C content determination and nucleic acid hybridization studies, genome structures can be directly compared only by sequencing DNA and RNA.

o Techniques for rapidly sequencing both DNA and RNA are now available; thus far RNA sequencing has been used more extensively in microbial taxonomy. Most attention has been given to sequences of the 5S and 16S rRNAs isolated from the 50S and 30S subunits,

o The rRNAs are almost ideal for studies of microbial evolution and relatedness since they are essential to a critical organelle found in all microorganisms. Their functional role is the same in

o Furthermore, their structure changes very slowly with time, presumably because of their

o Because rRNA contains variable and stable sequences, both closely related and very distantly related microorganisms can be compared. This is an important advantage as distantly related

Molecular Chronometers

The sequences of nucleic acids and proteins change with time and are considered to be molecular chronometers. This concept, first suggested by Zuckerkandl and Pauling (1965), is important in the use of molecular sequences in determining phylogenetic relationships and is based on the assumption that there is an evolutionary clock.



It is thought that the sequences of many rRNAs and proteins gradually change over time without destroying or severely altering their functions. One assumes that such changes are selectively neutral, occur fairly randomly, and increase linearly with time. When the sequences of similar molecules are quite different in two groups of organisms, the groups diverged from one another a long time ago. Phylogenetic analysis using molecular chronometers is somewhat complex because the rate of sequence change can vary; some periods are characterized by especially rapid change.



Furthermore, different molecules and various parts of the same molecule can change at different rates. Highly conserved molecules such as rRNAs are used to follow large-scale evolutionary changes, whereas rapidly changing molecules are employed in following speciation.

Bergey's Manual of Systematic Bacteriology

It gives the acce Manual of Systematic Bacteriology not phylogenetically homogeneo cell shape, Gram staining characteristics, oxygen relationships, classify prokaryotes. The second edition of Bergey's d 25 phyla. Comparisons of this new classification. The second edition will have five volumes. The general organization of the five volumes is summarized and briefly outlined below.

(1) Volume 1: The Archaea and the Deeply Branching and Phototrophic Bacteria

This volume describes the archaea, cyanobacteria, green sulfur and non-sulfur bacteria, deinococci, and other deeply branching groups.

( 2) Volume 2: The Proteobacteria

All of the proteobacteria (purple bacteria) are placed in this volume and are divided into five major groups based on rRNA sequences and other characteristics:

(3)Volume 3: The Low G + C Gram- Positive Bacteria .

This volume contains gram-positive bacteria with G + C content below about 50%. Some of the major groups are the clostridia, bacilli, streptococci, and staphylococci. Mycoplasmas also are placed here.

(4)Volume 4: The High G + C Gram- Positive Bacteria. Gram-positive bacteria with G + C content above around 50 to 55% are in this volume. Such groups as Corynebacterium, Mycobacterium, Nocardia, and the actinomycetes are located here.

(5)Volume 5: The Planctomycetes, Spirochaetes, Fibrobacteres, Bacteroidetes, and Fusobacteria. Volume 5 has a variety of different gram-negative bacterial groups. The most practically important examples are the chlamydias and the spirochetes.

9.4 NATURAL HISTORY OF INDIAN SUBCONTINENTS

Snapshot

1. Bird migration is the regular seasonal movement, often north and south along a flyway between breeding and wintering grounds, undertaken by many species of birds.

2. Migration, which carries high costs in predation and mortality, including from hunting by humans, is driven primarily by availability of food. Migration occurs mainly in the Northern Hemisphere where birds are funnelled on to specific routes by natural barriers such as the Mediterranean Sea.

3. Bird movements include those made in response to changes in food availability, habitat, or weather. Sometimes, journeys are not termed "true migration" because they are irregular (nomadism, invasions, irruptions) or in only one direction (dispersal, movement of young away from natal area).

4. The control of migration, its timing and response are genetically controlled and appear to be a primitive trait that is present even in non-migratory species of birds. The ability to navigate and orient themselves during migration is a much more complex phenomenon that may include both endogenous programs as well as learning.

5. Migrating birds can lose their way and appear outside their normal ranges. This can be due to flying past their destinations as in the "spring overshoot" in which birds returning to their breeding areas overshoot and end up further north than intended.

6. Large scale climatic changes, as have been experienced in the past, are expected to have an effect on the timing of migration Studies have shown a variety of effects including timing changes in migration, breeding as well as population variations

9.4.1 Migration of Species

Migration is the regular, recurrent, cyclical seasonal movement of populations from one geographic location to another. It is marked by the eventual return to the original place of departure. Migration is most evident among birds that usually follow a yearly cycle of migration. In some cases this migration is obvious and involves huge distances but at other times it is much more subtle.

Migrating animals are found in all major branches of the animal kingdom. They include taxa as diverse as fish, crustaceans, amphibians, reptiles, insects, mammals and slime moulds. The distance covered during some of the journeys, and the altitude at which they can take place, are simply astonishing. Let’s take a closer look at the migrations un

SMALLESTMIGRANT

Largestmigrant

Longestmammalmigration

Longestinsectmigration

Longestrecordedround-trip

Highestmigrationaltitude

1. One of the longest non-stop flights is performed by the bar-tailed godwit (Limosa lapponica). The L. l. baueri subspecies breeds in Alaska and migrates south to its nonbreeding quarters in Australia and New Zealand. Tracking individuals using lightweight satellite tags revealed that these birds are able to cross the Pacific Ocean in a non-stop marathon flight lasting over 9 days, making it one of the most impressive feats among migratory animals.

Figure9.38Limosalapponica

2. Perhaps the best known insect migrant is the monarch butterfly (Danaus plexippus). At the end of every summer, more than 100 million individuals sweep across North America to overwinter up to 4,750 km further south in California and Mexico. The complete migration requires an intergenerational relay. No single individual makes the entire round trip, as the duration of these journeys exceeds their lifespan. Instead, the females lay eggs during the migration, from which the next generation of migrants emerges. Monarchs specialize on milkweeds (Asclepiadaceae), which contain substances that are poisonous to vertebrates and thus protect the monarch from many potential enemies.

Migration is an adaptive response to the seasonal or geographic variation of resources. The annual cycle of the seasons produces large differences in the duration and intensity of solar energy received in each hemisphere at any given time. Many migrants take advantage of favorable food and weather conditions offered in certain areas during

For example, young salmon migrate to sea to take advantage of the great abundance of food and high growth potential available there, but must someday return upstream to the small rocky tributaries required for spawning, a trip

9.4.1.1 Preparation for migration



Some migratory animals forage along their migratory routes, while others, such as the bar-tailed godwit crossing the Pacific Ocean, do not.

Most migrants therefore feed intensively prior to departing for their journey to boost their fuel stores. This behaviour is known as hyperphagia, which is triggered by an internal circannual rhythm, and is seen in species as varied as monarch butterflies, caribou, and baleen whales.

The main source of energy used for migration is fat. Fat stores about 8–10 times more energy than the equivalent mass of either carbohydrate or protein, making fat the fuel of choice.

Migrants are capable of storing and mobilizing large amounts of fat: birds that fly long distances can double their body weight prior to departure, and a monarch butterfly can store up to 125% of its lean dry weight as fat.

As migration is energetically expensive, some migrants minimize excess weight and maximize flight efficiency by adjusting the size of their internal organs. In some avian migrants, organs related to flight, such as heart and flight muscles, increase in size in preparation for migration

By contrast, organs related to feeding (e.g., stomach, gut, liver, and kidneys) become smaller before departure and return to normal size upon arrival, when feeding and digestion resume

Similar changes are observed in some insects: for example, monarch butterflies migrating south through North America in the autumn have no sexual organs — these only develop the following spring in the surviving individuals

9.4.1.1 Trigger for Migration



In birds, there is a clear association between day length and the onset of migration.

Dark eyed juncos (Junco hyemalis) and American crows (Corvus brachyrhynchos) kept in artificially lengthened light periods move north when released, while controls, kept under natural light conditions, move south.

Hormones are also known to play a role in controlling migration. Bird migration is thought to depend on gonadal condition in spring, but not in fall.



In many insects, changes in the activity of juvenile hormone are responsible for transitions between migratory and reproductive life stages, and the gregarious swarms of locusts are under the influence of the hormone serotonin.

Figure 9. 39 Danaus plexippuson milkweed

The connections between day length, annual reproductive cycle and migration are now well established in birds, fishes, and other migrants.

9.4.1.2 Types of migration

There are lots of different kinds of migration. These terms are used to describe attributes of migration such as timing, direction, the reason for migration, and how many of the species migrate. More than one term can be used to describe one species migration patter. Some common types of migration are:



Seasonal migration: It is migration that corresponds with the change in seasons. Most migration fall within this category. Many altitudinal, longitudinal, latitudinal, and reproductive migrations take place when the seasons change.



Latitudinal migration animals north and south. The geese flying south for the winter is one of the most recognizable examples of latitudinal migration. By moving north and south, animals are changing their climate. In the northern hemisphere, the winters are colder as you move north and warmer as you move south. On the other hand, summers in the north can be rich in food, especially in the far north where summers are short, but the days are very long.



Altitudinal migration eatures such as mountains. While food may be plentiful in alpine meadows in summer, the winters will be colder and have more snow as you move higher up. Many animals take advantage of the summers, and then move to lower more moderate elevations during the



Reproductive migration: is the movement of animals to bear young. The area may be safer for the young because of fewer predators or more shelter from predators. In other cases, the area is safer because the animal requires a different type of h

Nomadic migration is the movement of animals not between known areas, but it looks to us more like wandering. Grazing animals will move across larger expanses as the grasses get eaten and they travel to greener pastures.

Removal migration is the migration of animals that don't come back. This can be when resources such as food, water or shelter are no longer available to animals where they are. The environment can have changed, through fire, flooding, invasive plant species or human development or other causes and the animals need to leave to survive. Another cause of removal migration is when the resources haven't changed, but the population gets too big, there are too many animals and many of them leave to find food, water and shelter elsewhere. Removal migration is what brought immigrants to America in the 1800s.

Complete migration is when virtually all members of the species leave their breeding range during the nonbreeding season. Many North American birds are complete migrants. Most complete migrants breeding in northern temperate and arctic areas (such as Alaska) of North America, Europe, and Asia. Complete migrants travel incredible distances, sometimes more than 15,000 miles (25,000 kilometers) per year. The wintering areas for most complete North American migrants are South and Central America, the Caribbean basin, and the southern most United States.



Partial migration: The most common type of migration is partial migration. Partial migrant means that some, but not all, members of a species move away from their breeding grounds during the nonbreeding season. There is an overlap between breeding and nonbreeding ranges of the species. Species like Red tailed Hawk, Herring Gull, and Golden Eagles are partial migrants over much of their North American range.



Irruptive migration: Migrations that are not seasonally or geographically predictable are termed irruptive. Such migration may occur one year, but not again for many years. The distances and numbers of individuals involved area also less predictable than with complete or partial migrants. In some years,

irruptions can be over long distances and involve many individuals, or they can be short and involve only a few.

9.4.1.3 Studying migration

Bird Banding

Instrumental in studying migration were banding (also called ringing) studies. Banding dates back to 1899, when Danish teacher Hans Christian Mortensen visited European starling (Sturnus vulgaris) nests and gave each nestling an aluminum leg band engraved with a return address and a unique serial number. If anyone encountered one of his banded birds, they could send back information on the time and place where it was found. Since 1899, more than 200 million birds are estimated to have been banded worldwide, of which only a fraction have been recovered. However, even a recovery rate as low as 1 in 300 the average for small birds still provides valuable insights into the routes that migrants take. Alternatives to banding include labeling with dye and attaching plastic tags to the neck or back, which is also used for mammals

Radar

The rapid development of radar during the Second World War enabled actual migratory journeys to be plotted for the first time. Modern radar is powerful enough to pinpoint the height, speed, and wing beat rate of individual birds and bats. Its aquatic equivalent can detect shoals of fish moving underwater.

Tracking Devices

It is possible to study animal movements without directly observing an individual. Fitting animals with radio transmitters and using hand held or stationary antennas allows following their whereabouts within a range of several kilometers. Alternatively, satellite transmitters beam signals to orbiting satellites, which then relay the data back to computers on the ground. GPS tags use the satellites of the Global Positioning System to record data such as location and time. They can be attached to mammals with a neck collar or to medium-sized birds with a backpack. Even smaller are geolocators, which are miniature light level loggers that can record sunset and sunrise, from which the location of the individual can be reconstructed. Some weigh less than 1 g and can last for many years. However, they need to be retrieved to access the data they stor

Stable Isotopes

It is now possible to measure the amount of stable isotopes such as deuterium (a form of hydrogen), oxygen, carbon, nitrogen, and sulfur in the tissue of migrants. Isotope levels in the plumage of a migratory bird match that of the vegetation of its breeding ground and can therefore serve as an indication of its place of birth. The same technique has been used to establish the hatching place of individual monarch butterflies wintering in Mexico.

9.4.1.5 Migration Examples

Humpback whale of the Pacific Ocean head south in the fall to give birth to their young in subtropical waters off Hawaii, and then in late spring head north to spend the summer in the cold waters off Alaska that are rich with food.

Salmon t start their lives in freshwater streams, move to the open ocean for their adult lives, then return to their home stream to lay eggs.

Dall sheep of Noatak National Preserve are seasonal, altitudinal migrants that spend summers near the top of mountain ranges and then winter at lower elevations where there is less snow and food easier to find.

Arctic terns are complete migrants that spend all year in summer by alternating subpolar regions in the northern and southern hemispheres.

Golden eagles of Denali National Park and Preserve spend the summer in the north where there is plenty of food, and head south for the winter when there is less food in the north and the temperatures drop far below zero. While all of the golden eagles of Denali do migrate, golden eagles are considered partial migrants because those that live far enough south do not migrate.

Sea turtles return from ocean waters to the coast to lay eggs in the sand, where they hatch and head to the open ocean until it is their turn to lay eggs. They are another example of reproductive migrants.

Locusts change when they get too crowded and become more active and social creating large groups of insects that move across the land in search of new places with plenty of food (and fewer locusts). This adaptation to overcrowding is removal migration.

Great gray owls are an irruptive migrant, migrating southward only occasionally and in numbers that vary greatly. Northern finches and crossbills are also irruptive migrants.

9.4.2 Common Indian Birds and manmmals

The avifauna of India includes around 1301 species, of which 42 are endemic, 1 has been introduced by humans, and 26 are rare or accidental. Two species have been extirpated in India and 82 species are globally threatened. The Indian Peacock (Pavo cristatus) is the national bird of India. More recent birds discovered in India include the Bugun Liocichla which was discovered in Arunachal Pradesh in 2006. Besides this, a few birds considered to be extinct have been rediscovered an example being the Jerdon's Courser. Some others have been elevated from subspecies to full species. The mammal of India ranges in size from the Eurasian pygmy shrew (Sorex minutus) to the Asian Elephant (Elephas maximus). Many of the carnivores and larger mammals are restricted in their distribution to forests in protected areas, while others live within the cities in the close proximity of humans. Some species are common to the point of being considered vermin while others are exceedingly rare. Many species are known from just a few specimens in museums collected in the 19th and 20th centuries. These enigmatic species include nocturnal small mammals such as the Malabar Civet (Viverra megaspila). While the status of many of these species is unknown, some are definitely extinct

Life is broadly defined as the condition of an organism that exhibits growth through metabolism, reproduction, and adaptation to its environment. These characteristics separate living organisms from inanimate objects.

The cell is the basic unit of life, and an organism must be composed of at least one cell to qualify as a living thing.

The cells of every living organism contain deoxyribonucleic acid (DNA), a nucleic acid that holds the genetic instructions for the development and functioning of a life form. It is this substance that allows a living thing to grow and reproduce.

INDIAN SEASONS

9.4.3.1 INDIAN CLIMATES

Analyzed according to the Köppen system, the climate of India resolves into six major climatic subtypes; their influences give rise to desert in the west, alpine tundra and glaciers in the north, humid tropical regions supporting rain forests in the southwest, and Indian Ocean island territories that flank the Indian subcontinent. Regions have starkly different yet tightly clustered microclimates. The nation is largely subject to four seasons: winter (January and February), summer (March to May), a monsoon (rainy) season (June to September), and a post monsoon period (October to December). India's geography and geology are climatically pivotal: the Thar Desert in the northwest and the Himalayas in the north work in tandem to effect a culturally and economically break monsoonal regime. As Earth's highest and most massive mountain range, the Himalayan system bars the influx of frigid katabatic winds from the icy Tibetan Plateau and northerly Central Asia. Most of North India is thus kept warm or is only mildly chilly or cold during winter; the same thermal dam keeps most regions in India hot in summer.



India is home to an extraordinary variety of climatic regions, ranging from tropical in the south to temperate and alpine in the Himalayan north, where elevated regions receive sustained winter snowfall. The nation's climate is strongly influenced by the Himalayas and the Thar Desert

The Himalayas, along with the Hindu Kush mountains in Pakistan, prevent cold Central Asian katabatic winds from blowing in, keeping the bulk of the Indian subcontinent warmer than most locations at similar latitudes



Simultaneously, the Thar Desert plays a role in attracting moisture laden southwest summer monsoon winds that, between June and October, provide the majority of India's rainfall

Four major climatic groupings predominate, into which fall seven climatic zones that, as designated by experts, are defined on the basis of such traits as temperature and precipitation. They can be broadly classified as:

Tropical dry

A tropical rainy climate governs regions experiencing persistent warm or high temperatures, which normally do not fall below °F). India hosts two climatic subtypes that fall under this group. The most humid is the tropical wet climate that covers a strip of southwestern lowlands abutting the , and southern Assam. India's two island territories, Lakshadweep and the Andaman and Nicobar Islands, are also subject to this climate. Characterised by moder round temperatures, even in the foothills, its rainfall is seasonal but heavy

Tropical dry

A tropical arid and semi arid climate dominates regions where the rate of moisture loss through evapotranspiration exceeds that from precipitation; it is subdivided into three climatic subtypes. The first, a tropical semi arid steppe climate, predominates over a long stretch of land south of Tropic of Cancer and east of the Western Ghats and the Cardamom Hills. The region, which includes Karnataka, inland Tamil Nadu, western Andhra Pradesh, and central Maharashtra, gets between 400 750 millimetres (15.7 29.5 in) annually. It is drought prone, as it tends to have less reliable rainfall due to sporadic lateness or failure of the southwest monsoon

Most of western Rajasthan experiences an arid climatic regime. Cloudbursts are responsible for virtually all of the region's annual precipitation, which totals less than 300 millimetres (11.8 in). Such bursts happen when monsoon winds sweep into the region during July, August, and September. Such rainfall is highly erratic; regions experiencing rainfall one year may not see precipitation for the next couple of years or so. Atmospheric moisture is largely prevented from precipitating due to continuous downdrafts and other factors

Subtrpoical humid

Most of Northeast India and much of North India are subject to a humid subtropical climate. Though they experience hot summers, temperatures during the coldest months may fall as low as 0 °C (32 °F). Due to ample monsoon rains, India has only one subtype of this climate under the Köppen system: Cwa. In most of this region, there is very little precipitation during the winter, owing to powerful anticyclonic and katabatic (downward flowing) winds from Central Asia.

Mountains

India's northernmost areas are subject to a montane, or alpine, climate. In the Himalayas, the rate at which an air mass's temperature falls per kilometre (3,281 ft) of altitude gained (the dry adiabatic lapse rate) is 9.8 °C/km.

Areas south of the Himalayas are largely protected from cold winter winds coming in from the Asian interior. The leeward side (northern face) of the mountains receives less rain while the southern slopes, well exposed to the monsoon, get heavy rainfall. Areas situated at elevations of 1,070 2,290 metres (3,510 7,510 ft) receive the heaviest rainfall, which decreases rapidly at elevations above 2,290 metres (7,513 ft). The Himalayas experience their heaviest snowfall between December and February and at elevations above 1,500 metres (4,921 ft). Snowfall increases with elevation by up to several dozen millimetres per 100 metre (~2 in; 330 ft) increase. Elevations above 5,000 metres (16,404 ft) never experience rain; all precipitation falls a

9.4.3.2 INDIAN SEASONS

The Himalayan states, being more temperate, experience an additional two seasons: autumn and spring. Traditionally, Indians note six seasons, each about two months long. These are the spring (Sanskrit: vasanta), summer (grī ā), early autumn (śarada), late autumn (hemanta), and winter (śiśira). These are based on the astronomical division of the twelve months into six parts. The ancient Hindu calendar also reflects these seasons in its arrangement of mo There are four major seasons in Indian sibcontinent:

Winter

o Once the monsoons subside, average temperatures gradually fall across India. As the Sun's vertical rays move south of the equator, most of the country experiences moderately cool weather; te per degree of latitude. December and January are the coldest months, with mean temperatures of 10 °F) in Indian Himalayas. Mean temperatures are higher in the east and south, where they reach 20

o T 900 metres) in the southern low tracts, warm and temperate (900 2400 metres) and cold glacial and alpine (2400 ern high elevated mountain ranges

o The rest of North India, including the Indo Gangetic Plain, almost never receives snow. Temperatures in the plains occasionally fall below freezing, though never for more one or two days. Winter highs in Delhi range from

o Frigid winds from the Himalayas can depress temperatures near the Brahmaputra River

o he Himalayas have a profound effect on the climate of the Indian subcontinent and the Tibetan plateau by preventing frigid and dry Arctic winds from blowing south into the subcontinent, which keeps South Asia much warmer than corresponding temperate regions in the other continents. It also forms a barrier for the monsoon winds, keeping them from travelling northwards, and causing heavy rainfall in

o In South India, particularly the hinterlands of Maharashtra, Madhya Pradesh, parts of Karnataka, and Andhra Pradesh, somewhat cooler weather prevails. Minimum temperatures in western Maharashtra, Madhya Pradesh and Chhattisgarh hover around 10 °C (50 °F); in the southern Deccan Plateau, they reach 16 °C (61 °F).

o Coastal areas especially those near the Coromandel Coast and adjacent low elevation interior tracts are warm, with daily high temperatures of 30 °C (86 °F) and lows of around 21 °C (70 °F).

o The Western Ghats, including the Nilgiri Range, are exceptional; lows there can fall below freezing. This compares with a range of 12 14 °C (54 57 °F) on the Malabar Coast; there, as is the case for other coastal areas, the Indian Ocean exerts a strong moderating influence on weather.

Summer

o Summer in northwestern India lasts from April to July, and in the rest of the country from March to June. The temperatures in the north rise as the vertical rays of the Sun reach the Tropic of Cancer. The hottest month for the western and southern regions of the country is April; for most of North India, it is May. Temperatures of 50 °C (122 °F) and higher have been recorded in parts of India during this season

o In cooler regions of North India, immense pre monsoon squall line thunderstorms, known locally as "Nor'westers", commonly drop large hailstones. In Himachal Pradesh, Summer lasts from mid April till the end of June and most parts become very hot (except in alpine zone which experience mild summer) with the average temperature ranging from 28 °C (82 °F) to 32 °C (90 °F).

o Winter lasts from late November till mid March. Snowfall is generally common in alpine tracts that are above 2,200 metres (7,218 ft), especially those in the higher- and trans-Himalayan regions.

o Near the coast the temperature hovers around 36 °C (97 °F), and the proximity of the sea increases the level of humidity. In southern India, the temperatures are higher on the east coast by a few degrees compared to the west coast.

o By May, most of the Indian interior experiences mean temperatures over 32 °C (90 °F), while maximum temperatures often exceed 40 °C (104 °F). In the hot months of April and May, western disturbances, with their cooling influence, may still arrive, but rapidly diminish in frequency as summer progresses

o Notably, a higher frequency of such disturbances in April correlates with a delayed monsoon onset (thus extending summer) in northwest India. In eastern India, monsoon onset dates have been steadily advancing over th

o Altitude affects the temperature to a large extent, with higher parts of the Deccan Plateau and other areas being relatively cooler. Hill stations, such as Ootacamund ("Ooty") in the Western Ghats and Kalimpong in the eastern Himalayas, with average maximum temperatures of around 25 °C (77 °F), offer some respite from the heat. At lower elevations, in parts of northern and western India, a strong, hot, and dry wind known as the Looblows in from the west during the daytime; with very high temperatures, in some cases up to around 45 °C (113 °F); it can cause fatal cases of sunstroke

 Monsoon

o The southwest summer monsoon, a four month period when massive convective thunderstorms dominate India's weathe

o A product of southeast trade winds originating from a high pressure mass centred over the southern Indian Ocean, the monsoonal torrents supply over 80% of India's annual rainfall

o Attracted by a low centred over South Asia, the mass spawns surface winds that ferry humid air These inflows ultimately result from a northward shift of the local jet stream, which itself results from rising summer temperatures over Tibet and the Indian subcontinent. The void left by the jet stream, which switches from a route just south of the Himalayas to one tracking north of Tibet, then attracts warm, humid air

o The southwest monsoon arrives in two branches: the Bay of Bengal branch and the Arabian Sea branch. The latter extends towards a low pressure area over the Thar Desert and is roughly three times stronger than the Bay of Bengal branch. The monsoon typically breaks over Indian territory by around 25 May, when it lashes the Andaman and Nicobar Islands in the Bay of Bengal. It strikes the Indian mainland around 1 June near the Malabar Coast of Kerala

o By the first week of July, the entire country experiences monsoon rain; on average, South India receives more rainfall than North India. However, Northeast India receives the most precipitation. Monsoon clouds begin retreating from North India by the end of August; it withdraws from Mumbai by 5 October. As India further cools during September, the southwest monsoon weakens. By the end of Nove

Post-monsoon

o During the post monsoon months of October to December, a different monsoon cycle, the northeast (or "retreating") monsoon, brings dry, cool, and dense Central Asian air masses to large parts of India.

o Winds spill across the Himalayas and flow to the southwest across the country, resulting in clear, sunny skies hough the India Meteorological Department (IMD) and other sources refers to this period as a fourth ("post monsoon") season, other sources designate only three seasons

o Depending on location, this period lasts from October to November, after the southwest monsoon has peaked. Less and less precipitation falls, and vegetation begins to dry out. In most parts of India, this period marks the transition from wet to dry seasonal conditions. Average daily maximum temperatures range between 28 and 34 °C (82 and 93 °F).

o The northeast monsoon, which begins in September, lasts through the post monsoon seasons, and only ends in March. It carries winds that have already lost their moisture while crossing central Asia and the vast rain shadow region lying north of the Himalayas.

o hey cross India diagonally from northeast to southwest. However, the large indentation made by the Bay of Bengal into India's eastern coast means that the flows are humidified before reaching Cape Comorin and rest of Tamil Nadu, meaning that the state, and also some parts of Kerala, experience significant precipitation in the post-monsoon and winter periods.

o However, parts of West Bengal, Orissa, Andhra Pradesh, Karnataka and Northeast India also receive minor precipitation from the northeast monsoon.

Critical thinking Questions

1.

2. 3.

9.5 ORGANISM OF HEALTH AND AGRICULTURAL IMPORTANCE

Snapshot

1. Human parasites include various protozoa and worms which may infect humans, causing parasitic diseases.

Human parasites are divided into endoparasites, which cause infection inside the body, and ectoparasites, which cause infection superficially within the skin.

3. The cysts and eggs of endoparasites may be found in feces which aids in the detection of the parasite in the human host while also providing a means for the parasitic species to exit the current host and enter other hosts.[1]- Although there are number of ways in which humans can contract parasitic infections, observing basic hygiene and cleanliness tips can reduce its probability.

4. Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants.

5. Plant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases.

9.5.1 COMMON PARASITES OF HUMAN

Although safe and effective treatment and control methods exist for most internal and external parasites, many animals continue to suffer from preventable parasitic infections. Geographical location, lifestyle, housing conditions and species play a role in which parasites are likely to be a problem. Internal and external parasites can cause great discomfort, transmit disease to animals and humans and significantly interfere with the relationship between people and animals. The presence of parasites on an animal can cause family and community members to distance themselves physically and emotionally from the animal. The ‘mangy’ dog will be perceived and treated differently than a dog who appears healthy. This perception may profoundly influence the level of care and attention an animal receives. With proper testing and the administration of preventive medication and measures, most common parasites can be controlled effectively. Because of the impact on animal and human health, it is important that we encourage comprehensive parasite control as a priority in preventive health care. Of course, recommendations for treatment and prevention are only effective if the client is able to comply. Knowledge of the available treatment options and awareness of the resources available to the client and the community are important in developing successful treatment recommendations. Each parasite species has two pages. The first of the two contains basic information such as: life cycle, symptoms, diagnosis and treatment. The second page has pictures and videos. If you do not have any specific parasite in mind, then start by reading below some basic information about parasitic diseases. nternal parasites and their waste products can reduce food absorbtion by causing inflammation of the intestinal wall. Food might also get stuck resulting in excessive toxins, smelly farts, bad breath and bloating. If organs such as liver and kidneys cannot get rid of the toxins, then poisons might get out through skin causing skin problems and hair loss. Damaged nervous system and stress hormones give origin to insomnia. Some bloodsucking worms leave open wounds resulting in darker feces. The loss of blood can cause iron deficiency, anemia and dizziness. Other symptoms caused by parasitic infections include (but are not limited to):

pain

(bloody feces)

(coughing up blood)

(yellowish eye whites and skin)

loss

pain and spasms

nausea or vomiting

rash

hemorrhage (bleeding rectum)

prolapse (rectum coming out, when pushing hard)

of breath

stomach pain

s,mucocut aneous,

stain

of phlebotomine sandflies

neous leishmaniasis–

World;Mucocuta

leishmaniasis-

Blastocystosis

Balantidiumcoli

intestinal mucosa, may become invasive in some patients

stool (diarrhea=ciliated trophozoite; solid stoollargecystwith horseshoe shaped nucleus)

Ingestion of cyst, zoonoticinfection acquired from pigs (feces)

swelling

sweating and grinding teeth while sleeping. Infected body is filled with poisons and harmful stress hormones. Exercising is a good way to keep blood and lymphatic fluids flowing. White blood cells also travel to infection areas quicker. Faster metabolism helps to get rid of toxins. Sweating and urinating are quick ways to excrete poisons. Diarrhea can be compensated by drinking enough. Vitamins protect cells and fiber sweeps the gastrointestinal tract clean. Garlic, black walnut hull, cloves and wormwood are natural herbs damaging parasites and their eggs.

Protozoan Organisms:

Protozoa are unicellular organisms that feed on organic matter. There are over 30 000 protozoan species but not all are parasites. Protozoa usually have flagella and thus can actively move. They usually consume food by surrounding it with their cell membrane. Some species sweep food into their mouth parts. The food is broken down in cell organs called vacuoles. Protozoa multiply by fission either asexually or sexually. Some protozoan parasites have different forms during their life cycle. Cysts for example are multilayered shells that can endure rough conditions for long periods of time. They are passive and cannot move nor eat. When cysts get back to their feeding environment they turn back into the active stage which is trophozoite. This is called excystation. The transformation into a cyst is called encystation.

Common name of organism/disease

Lancetliverfluke

Liver flukeFasciolosis

Fasciolopsiasisintestinalfluke

Paragonimiasis LungFluke

urinary schistosomiasis

Common name of organism/disease

TapewormTapeworminfection

Diphyllobothriasistapeworm

multiceps

Diphyllobothrium latum

Taenia saginataBeeftapeworm

Bertielliasis

intestines, blood

stool (microsco pe)

StoolIntestines

ingestion of raw freshwaterfish Europe, Japan, Uganda,Peru, Chile

ingestion of undercookedbeef worldwide distribution

Contact with non humanprimates rareStoolIntestinesBertiella mucronata,Bertiella studeri

Taenia soliumPorktapeworm

StoolIntestines

ingestion of undercookedpork worldwide distribution

Helminthes Organism:

The word ‘helminth’ is a general term meaning ‘worm’, but there are many different types of worms. Many helminths are free-living organisms in aquatic and terrestrial environments whereas others occur as parasites in most animals and some plants. Parasitic helminths are an almost universal feature of vertebrate animals; most species have worms in them somewhere.

Three major assemblages of parasitic helminths are recognized: the Nemathelminthes (nematodes) and the Platyhelminthes (flatworms), the latter being subdivided into the Cestoda (tapeworms) and the Trematoda (flukes)

Tapeworm

Tapeworms are flat segmented worms that live in the intestines of some animals. Animals can become infected with these parasites when grazing in pastures or drinking contaminated water.

Eating undercooked meat from infected animals is the main cause of tapeworm infection in humans. Although tapeworms in humans usually cause few symptoms and are easily treated, they can sometimes cause serious, life-threatening problems.

Flukes

They have small flat leaf-like bodies with oral and ventral suckers and a blind sac-like gut. They do not have a body cavity (acoelomate) and are dorsoventrally flattened with bilateral symmetry Most species are hermaphroditic (individuals with male and female reproductive systems) although some blood flukes form separate male and female adults

hematoxylin.

Roundworms:

A roundworm infection is also sometimes known as ascariasis or acaris. Roundworms are parasites. This means that they use the human body to stay alive, feed and reproduce. Roundworms are the only worms found in human faeces that are roughly the size of an earth worm. A roundworm infection can occur if someone swallows the microscopic ascaris eggs in contaminated food or water. It is also possible for someone to transfer eggs from their hands to their mouth if they touch contaminated soil.

Common name of organismordisease

Bedbug

Headlouse-Pediculosis

Latin name (sorted)

Table:10Ectoparasites

Body parts

Transmission/VectorPrevalenceDiagnostic

WorldwidevisualskinCimicidaeCimex lectularius

hairfolliclesPediculus humanus

Crablouse-Pediculosis

Demodex-Demodicosis

Screwworm,Cochliomyia

Ectoparasites:

Common worldwide visual identification under magnification

Worldwidevisual identification pubic area, eyelashes Phthiruspubis

sharing of clothing andbedding

headto-headcontact

skin-to-skin contact suchassexualactivity

Parasites that live on the surface of the host are called ectoparasites Some ectoparasites, such as monogenean worms, rely on direct contact between hosts. Ectoparasitic arthropods may rely on host-host contact (e.g. many lice), shed eggs that survive off the host (e.g. fleas), or wait in the external environment for an encounter with a host (e.g. ticks). Some aquatic leeches locate hosts by sensing movement and only attach when certain temperature and chemical cues are present

9.5.2 COMMON PLANT DISEASES

Plant pathology (also phytopathology) is the scientific study of plant diseases caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Not included are ectoparasites like insects, mites, vertebrate, or other pests that affect plant health by consumption of plant tissues. Plant pathology also involves the study of pathogen identification, disease etiology, disease cycles, economic impact, plant disease epidemiology, plant disease resistance, how plant diseases affect humans and animals, pathosystem genetics, and management of plant diseases

COMMON PLANT DISEASES:

ANTHRACNOSE

It is caused

anthracnose infected plants develop dark lesions on stems, leaves or fruit. These lesions often become covered with pink spore masses. Dieback often occurs

BACTERIAL LEAF SPOT

Symptoms: Infected plants have brown or black water-soaked spots on the foliage, sometimes with a yellow halo, usually uniform in size. The spots enlarge and will run together under wet conditions . Members of the Prunus family (cherry, plum, almond, apricot, peach) are particularly susceptible. The fruit may appear spotted or have sunken brown areas. Bacterial leaf spot will also attack tomatoes, peppers and cabbage family crops in vegetable gardens.

BROWN ROT

Symptoms: The most common fungal disease affecting the blossoms and fruit of almonds, apricots, cherries, peaches and plums. Developing or mature fruits show circular or brown spots that spread rapidly over the surface and light gray masses of spores are produced on the rotted areas. Rotted tissue remains relatively firm and dry.

CROWN GALL

A common plant disease caused by the bacterium Agrobacterium tumefaciens. Symptom: crown gall occurs on many woody shrubs and some herbaceous plants, including grapes, raspberries, stone fruits and roses. Susceptible plants are infected through fresh wounds or abrasions, many of which are a result of pruning, freeze injury, soil insects, cultivation and other factors that may damage plants

DOWNY MILDEW

Symptom: affects many plants and appears as yellow to white patches on the upper surfaces of older leaves. On the undersides, these areas are covered with white to grayish, cotton-like fungi. As the disease progresses leaves may eventually turn crisp and brown and fall off even though the plant has ample water.

EARLY BLIGHT

As the disease progresses leaves may eventually turn crisp and brown and fall off even though the plant has ample water. It first appears on the lower, older leaves as small brown spots with concentric rings that form a "bull's eye" pattern. As the disease matures, it spreads outward on the leaf surface, causing it to turn yellow, wither and die.

GREY MOLD

Caused by the fungus Symptom: It can be identified stems, flowers fungus spor often develop black, stone-lik found near the soil surface or in the densest area

LEAF CURL

Caused by Taphrina deformans.

Symptom:It appears in spring as reddish areas on developing leaves. These areas become thickened and puckered, causing leaves to curl and distort. When severe, leaf curl can substantially reduce fruit production.

MOSAIC VIRUS

Leaves may be wrinkled or curled, growth may be stunted and yields are greatly reduced. Infected fruit appears mottled and develops raised "warty" areas. It is often mishappen. Affecting a wide variety of plants, including roses, beans, tomatoes, and peppers, mosaic is a viral disease.

POWDERY MILDEW

Powdery mildew starts on young leaves as raised blister-like areas that cause leaves to curl, exposing the lower leaf surface. Infected leaves become covered with a white to gray powdery growth, usually on the upper surface. Low soil moisture combined with high humidity levels at the plant surface favors this disease.

Figure 9.43 Crown gall

Figure 9.44 Downy

Figure 9.45 Grey

Figure 9.46 Mosaic virus

Critical thinking Questions

1. Many infected animals are induced by the parasitic microsporidianstodevelop huge cells, known as xenomas, which are fullofspores.Giventheirlarge size,whatshould be true ofthe xenomas?

2. 3.

Today,allidentifiedlivingorganismsarescientificallynamedandcategorizedaccording Swedish scientistCarl ,Linnaeusdividedand classifieddifferentlivingorganisms arankingscale:kingdom,phylum,class,order,family, genus,andspecies.

Scientistsestimatethatanywherefromfivemillion plantsand animalscurrently thesespecieshavebeen identified.

Insectspeciesaccountfor Therearenearly Mammalsmake Thetheory evolution,whichexplainshowlivingthingschangeovertimethroughnatural selection,wasfirstpublicized thisnatural phenomenon Worldwide,therearecurrentlyjustover6.7billionpeopleliving .Thepopulation of males

9.6 ANSWER TO CRITICAL THINKING

Chapter 1

1. Why is kingdom Monera no longer considered a valid taxon?

Ans: the kingdom monera included bacteria and archea, but we now know that these organisms are in separate domains. Kingdoms are subsets of domains, so a single kingdom that includes taxa from different domains is not valid.

2. Why do some biologist describe the mitochondria of diplomonads and parabasalids as’highly reduced’?

Ans: Their mitocondria do not have an electron transport and hence cannot function in aerobic repiration.

3. In what sense is ‘fungus animal’ a fitting description of a s

Ans: Slime molds are fungus-like in that they produce fruiting bodies that aid in the dispersal of spores, and they are animal like in that they are motile and ingest food. However, slime molds are more closely related to gymnamoebas and entamoebas than to fungi or animals.

Chapter 2

1. Why do researchers identify charophytes rather than another group of land plants?

Ans: land plants share some key traits only with charophytes; rings of cellulose-synthesizing complexes, presence of peroxisomes enzyme, similarity in sperm structure and the formation of phragmoplast in cell division

2. What would the human life cycle be

Ans: the multicelluar diploid phase of the life cycle would not produce gametes. Instead both males and females would produce haploid spores by meiosis. These spores would give rise to multicellular haploid stage of gametes and reproduce sexually. An individual at the multicellular haploid stage of gametes of the human life cycle might look us, or it might look completely different.

3.Give three examples of how structure fits function in bryophytes?

Ans: Large surface area of protonema enhances absorption of water and minerals; the vase-shaped archegonia protect egges during fertilization and transport nutrients to the embryos via placenta transfer cells; the stack-like seta conducts nutrients from the gametophytes to the capsule where spores are produced.

Chapter 3

1. Which taxon is essentially equivalent to the "embryophytes"?

Ans: Plantae

2. What is the functional role of sporopollenin?

Ans: reduce dehydration

3. On a field trip, a student in a marine biology class collects an organism that has differentiated organs, cell walls of cellulose, and chloroplasts with chlorophyll . Based on this description, the organism could be a brown alga, a red alga, a green alga, a charophyte recently washed into the ocean from a freshwater or brackish water source, or a land plant washed into the ocean. The presence of which of the following features would definitively identify this organism as a land plant?

Ans: embryos

Chapter 4

1. In addition to seeds, which of the following characteristics are unique to the seed-producing plants?

Ans: Pollen

2. In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar which?

Ans: fern gametophyte bearing only antheridia.

3. A researcher has developed two stains for use with seed plants. One stains sporophyte tissue blue; the other stains gametophyte tissue red. If the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur?

Ans: The pollen grains will have red interiors and blue exteriors

Chapter 5

1. Many infected animals are induced by the parasitic microsporidians to develop huge cells, known as xenomas, which are full of spores. Given their large size, what should be true of the xenomas?

Ans: The parasite must endow the xenoma with some way to overcome its unfavorable surface area-to-volume ratio

2. In both lichens and mycorrhizae, what does the fungal partner provide to its photosynthetic partner?

Ans: Water and minerals

3. Which of the following terms refers to symbiotic relationships that involve fungi living between the cells in plant leaves?

Ans: endophytes

Test Yourself Test Yourself

Part B

1. In general, how do algae and protozoans differ?

a)Protozoans can move and algae cannot b)Algae are free-living and protozoans are parasite c) Protozoans are autotrophic, and algae are heterotrophic d)Algae are photosynthetic and almost all protozoans are heterotrophic

2.Which technique is routinely used among plants for establishing genetic relationship?

a)Amino acid sequence b)Serological investigation c) Iso-enzyme profiling d)Chromosomal morphology

3.Which is NOT a characteristic of numerical taxonomya)The greater the content of information in taxa of classification and the more character on which it is based, the better is classification b)Every character is of equal weight in creating natural taxa c) Classification is based on percentage (%) similarity coefficient for each OTU.

d)Phylogenetic inferences cannot be made from the taxonomic structure of a group and from character correlation

4. What is the difference between a threatened species and an endangered species?

a)A threatened species means that the population is likely to become endangered An endangered species has population numbers so low that it is likely to become extinct

b)A threatened species is already extinct. An endangered species means that the population’s numbers have increased greatly over the last 5 years

c) A threatened species means that the population is likely to become endangered. An endangered species is already extinct d)A threatened species and an endangered species are the same thing

5.Why do migratory birds go back to their earlier habitat in spring? a)weather becoming too hot in the regions b)scarcity of food in the region to which they migrate c) breeding instinct with change in climate and they breed only in original habitat d)hunting season commencing in spring

6.Which of the following is a hermaphrodite?

a)Earthworm b)Hookworm c) Bed bug d)Mosquito

7.Which of the following enzymes secreted by pancreas helps predatory animals to digest blood they drink from their prey?

a)Pepsin

b)Trypsin

c) Ptyalin

d)Fibrin

8.If the fins of a fish are damaged, which of the following activities would suffer?

The greatest amount of free energy is available at which of the

In general tropical rainforests are known to have a very high rsity of species. Which of the following is the least plausible

Which of the following insects have male helpers?

13. The major excretory product formed in birds and reptiles is: a)Urea b)Uric acid

c) Ammonia

d)Ammonium salts

14. When compared to the mammals, birds are less sensitive to temporary deprivation of water. Why? a)urea excretion in mammals entails a greater loss of water than in birds

b)the water requirement per unit weight in birds is less than that in mammals

c) absorption of water in guts is more efficient in birds than in mammals d)none of the above

15. A blue whale stranded on a beach will suffocate because: a)It needs to breathe water b)Its evaginated gills will dry out c) It will not be able to contract its diaphragm d)It will get air bubbles in its blood stream

16. Taenia solium (Tape worm) lives as a parasite in: a)pig

b)abdomen of man c) intestine of man d)Liver of man

17. Which of the following is a correct association of an animal germ layer with the tissues or organs to which it gives rise?

a) ectoderm: outer covering of digestive system b) endoderm: internal lining of blood vessels c) mesoderm: central nervous system d) mesoderm: skin

18. Which of the following terms or structures is properly associated only with animals? a)Hox genes b)Cell wall c) Sexual reproduction d)Chitin

19. Which of the following definition covers a greater number of organisms?

a)Class b)Genus c) Order d)Family

20. A system of classification based on all important morphological characters is termed as: a)Artificial system b)Natural System c) Genetic System d)Both b and c

21. Most bryophytes, such as mosses, differ from all other plants in that they a)do not produce flowers b)have cones but no seeds

c) have flagellated sperm d)lack vascular tissue

22. Not all species contribute equally to the integrity of an ecological community, with limited time and resources, it would be most reasonable to focus conservation efforts on

a)the large vertebrates

b)keystone species

c) primary producers d)exotic species

Which one of the following is a correct statement?

If you are asked to classify the various algae into distinct groups,

Which of these programs is used to preserve a species facing

In which kingdom would you classify the archaea and nitrogenfixing organisms, if the five-kingdom system of classification is used?

Research on the nothern spotted owl indicates that: owl population will stabilize if an adequate number of immature

b)metapopulations must be more closely spaced to compensate for the owl’s limited flight capacity c) setting aside marginal habitat encourages dispersion of owls into areas where reproductive success is unlikely d)the current owl population is too small to disperse into source habitats

28. The applications of ecological principles to return a degraded ecosystem to its natural state is characteristic of:

a)Bioremediation

b)Restoration ecology

c) Landscape ecology

d)Conservation ecology

29. Fungi producing usually eight spores in a sac like structure belong to which class?

a)Phycomycetes

b)Ascomycetes

c) Basidiomycetes

d)Deutromycetes

30. Besides erythrocytes, which other cell in the body can be attacked by Plasmodium?

a)Muscle cell b)Nerve cell c) Kidney cell d)Hepatocytes

31. Identify the alga known for a biological activity called bioluminescence?

a)Spirogyra b)Noctiluca

c) Cyclotella d)Chlorella

32. The venus flower basket is dried skeleton of? a)Euspongia b)Euplectella c) Spongilla d)Leucosolenia

33. What is the scientific name of the National bird of India?

a) Psittacula eupatra b) Passer domesticus c) Pavo cristatus d) Corvus splendens

34. A university biology department wishes to hire a scientist to work on the relationships among the wolves, moose, trees and grass species on an island. If you were charged with writing the job announcement, you should title the position

a)population geneticist

b)molecular biologist c) community ecologist d)organismic physiologist

35. What is the term which refers to all the chemical energy transformations that occur within a cell?

a)evolution b)metabolism c) adaptation d)homeostasis

36. Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available?

a) Some closely resemble animals, which lack cell walls.

b) Their cell walls are composed of very different biochemicals c) Some have cell walls only for support.

d) Some have cell walls only for protection from herbivores

Jams, jellies, preserves, honey, and other foodstuffs with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment

are unable to metabolize the glucose or fructose, and thus starve

Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this, which of the following is correct?

Some antibiotics can block protein synthesis in bacteria without

Translation can occur at the same time as transcription in

Some antibiotics can block the synthesis of peptidoglycan in the

If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent

Chloramphenicol is an antibiotic that targets prokaryotic (70S) ribosomes, but not eukaryotic (80S) ribosomes. Which of these questions stems from this observation, plus an understanding of eukaryotic origins?

a)Can chloramphenicol also be used to control human diseases that are caused by archaeans

b)Can chloramphenicol pass through the capsules possessed by many cyanobacteria

c) If chloramphenicol inhibits prokaryotic ribosomes, should it not also inhibit mitochondrial ribosomes d)prokaryotic ribosomes identical to eukaryotic ribosomes

41. In a hypothetical situation, the genes for sex pilus construction and for tetracycline resistance are located together on the same plasmid within a particular bacterium. If this bacterium readily performs conjugation involving a copy of this plasmid, then the result should be

a)a bacterium that has undergone transduction b)the rapid spread of tetracycline resistance to other bacteria in that habitat

c) the subsequent loss of tetracycline resistance from this bacterium d)the production of endospores among the bacterium's progen

42. Which process results in genetic recombination, but is separate from the process by which the population size of Paramecium increases?

a)budding b)meiotic division c) mitotic division d)conjugation

43. A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. This alga probably belongs to which group?

a)red algae b)brown algae c) green algae d)dinoflagellates

44. A large seaweed that floats freely on the surface of deep bodies of water would be expected to lack which of the following? e)thalli f) bladders g)holdfasts h)gel-forming polysaccharides

45. Hershey and Chase performed an elegant experiment that convinced most biologists that DNA, rather than protein, was the genetic material. This experiment subjected bacteria to the same gene transfer mechanism as occurs i) transduction. j) transformation. k)conjugation. l) binary fission

46. A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group?

a)diatoms b)foraminiferans c) radiolarians

d)gymnamoebas

47. The chloroplasts of all of the following are thought to be derived from ancestral red algae, except those of

a)green algae b)brown algae. c) dinoflagellates. d)diatoms.

48. If the Archaeplastidae are eventually designated a kingdom, and if land plants are excluded from this kingdom, then what will be true of this new kingdom?

a)It will be monophyletic b)It will more accurately depict evolutionary relationships than does the

Which of the following statements concerning protists is true?

All protists have mitochondria, though in some species they are much

The primary organism that transmits malaria to humans by its bite is

All slime molds have an amoeboid stage that may be followed by a

A gelatinous seaweed that grows in shallow, cold water and undergoes heteromorphic alternation of generations is most probably

Living diatoms contain brownish plastids. If global warming causes blooms of diatoms in the surface waters of Earth's oceans, how might this be harmful to the animals that build coral reefs? The coral animals, which capture planktonic organisms, may be

The coral animals' endosymbiotic dinoflagellates may get "shaded

The coral animals may die from overeating the plentiful diatoms, with

The diatoms' photosynthetic output may over-oxygenate the water.

52. The trophozoites of Giardia were first observed in 1681 in the diarrhea stools of the first known person to view protists with a microscope, a person named a)van Leeuwenhoek b)Isaac Newton c) Robert Hooke d)Robert Koch

53. In addition to seeds, which of the following characteristics are unique to the seed-producing plants? a)sporopollenin

b)lignin present in cell walls c) pollen d)use of air currents as a dispersal agent

54. In terms of alternation of generations, the internal parts of the pollen grains of seed-producing plants are most similar to a a)moss sporophyte b)fern gametophyte bearing only antheridia c) hermaphroditic fern gametophyte d)moss gametophyte bearing both male and female gametangia.

55. Gymnosperms differ from both extinct and extant (living) ferns because they a)are woody b)have macrophylls c) have pollen. d)have sporophylls

56. Which of the following statements correctly describes a portion of the pine life cycle? a)Female gametophytes use mitosis to produce eggs b)Seeds are produced in pollen-producing cones. c) Pollen grains contain female gametophytes. d)A pollen tube slowly digests its way through the triploid endosperm

57. Which of the following statements is true of monocots? a)They are currently thought to be polyphyletic b)The veins of their leaves form a netlike pattern c) They, along with the eudicots, magnoliids, and basal angiosperms, are currently placed in the phylum Anthophyta d)Each possesses multiple cotyledons

58. The generative cell of male angiosperm gametophytes is haploid. This cell divides to produce two haploid sperm cells. What type of cell division does the generative cell undergo to produce these sperm cells?

a)binary fission b)mitosis c) meiosis d)mitosis without subsequent cytokinesis

59. Many mammals have skins and mucous membranes that are sensitive to phenolic secretions of plants like poison oak (Rhus). These secondary compounds are primarily adaptations that a)prevent desiccation b)favor pollination c) foster seed dispersal d)inhibit herbivory.

60. A botanist was visiting a tropical region for the purpose of discovering plants with medicinal properties. All of the following might be ways of identifying potentially useful plants except

a)observing which plants sick animals seek out b)observing which plants are the most used food plants c) observing which plants animals do not eat. d)collecting plants and subjecting them to chemical analysis

61. If the beetles survive by consuming cycad pollen, then whether the beetles should be considered mutualists with, or parasites of, the cycads depends upon a)the extent to which their overall activities affect cycad reproduction b)the extent to which the beetles are affected by the neurotoxins the extent to which the beetles damage the cycad flowers the distance the beetles must travel between cycad microsporophylls

If one were to erect a new taxon of plants that included all plants that are pollinated by animals, and only plants that are pollinated by

In individual insects of some species, whole chromosomes that carry larval genes are eliminated from the genomes of somatic cells at the time of metamorphosis. A consequence of this occurrence is we could not clone a larva from the somatic cells of such an adult the descendents of these adults do not include a larval stage metamorphosis can no longer occur among the descendents of such

Soon after the coelom begins to form, a researcher injects a dye into the coelom of a deuterostome embryo. Initially, the dye should

65. What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates a)have a body cavity, whereas pseudocoelomates have a solid body b)contain tissues derived from mesoderm, whereas pseudocoelomates have no such tissue c) have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not. d)have a complete digestive system with mouth and anus, whereas pseudocoelomates have a digestive tract with only one opening

1. Which of the following does NOT represent homeostasis?

a.Sensors detect CO2 levels in the blood and trigger an increase or decrease in the rate of breathing.

b.When body temperature drops, you shiver to generate heat; when your body heats up, you sweat and the evaporation cools you.

c. Feelings of hunger and then fullness affect the length of time and quantity of food you eat, keeping your weight near a "set point." d.Energy is captured by plants, then transferred to consumers and decomposers, and eventually lost as heat.

2.Protozoans called choanoflagellates live in small clusters. They look very much like choanocytes, special feeding cells found in sponges, which are simple animals. Why might biologists find choanoflagellates of great evolutionary interest?

a) They show how the very first organisms might have lived.

b) They might show how the first heterotrophs lived. c) offer hint about origin of multicellular organism d) They suggest what the first eukaryotes might have been like

3.The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of beta-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that a)Radiata should be a true clade

b)The radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait. c) Cnidaria may someday replace Acoela as the basal bilaterians d)Both b and d

4.What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates have a body cavity, whereas pseudocoelomates have a solid body?

a)contain tissues derived from mesoderm, whereas pseudocoelomates have no such tissue b)have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not c) have a complete digestive system with mouth and anus, whereas pseudocoelomates have a digestive tract with only one opening d)have a gut that lacks suspension within the body cavity, whereas pseudocoelomates have mesenteries that hold the digestive system in place.

5.A researcher is trying to construct a molecular-based phylogeny of the entire animal kingdom. Assuming that none of the following genes is absolutely conserved, which of the following would be the best choice on which to base the phylogeny? a)genes involved in chitin synthesis b)collagen genes c) beta-catenin genes

d)genes involved in eye-lens synthesis

6. One classic definition of life is "a self-replicating molecular assemblage." However, clay particles (in clay soil) contain layered aluminum and iron compounds that determine the pattern of the adjacent layers of sediment. This is technically a self-replicating molecular assemblage. Which of the following conclusions is most accurate?

a)It is not living because it is a simple repetitive process without the ability to evolve or respond to the environment.

It is not living because there is no carbon involved; otherwise, such

It is not living because there were no molecular changes (or

Studying a brick does not predict the design of a skyscraper. Intense

examination of muscle tissues does not allow you to predict the design of a kangaroo or clam. The structure of chlorophyll does not dictate the unique structure of a tree. What do these cases

emergent properties that cannot be predicted by examining their emergent properties that are easily predicted by examining their determinism, or how all phenomena are predictable effects of causes

An earlier classification grouped organisms by whether they inhabited the air, land or sea. However, the five-kingdoms-of-life and three-domain system divided into class-order-family-genus-species as described in this chapter is superior because of which reason? better represents the origin of features held in common–the unity of the diversity of life for groups organisms based on similarities related to their structure and

ome members of a species have a genetic change that causes them to be better suited to their environment. These members survive to reproduce and pass these genetic changes to their offspring. This can be best described by which of the following word?

a)adaptation b)natural selection c) the driving force of evolution d)all of the above

10. A 45 year old female complains of lower abdominal pain and vaginal discharge. On examination there is cervicitis along with a mucopurulent cervical discharge. Which of the following would be the

best approach to isolate the possible causative agent?

a)Culture chocolate agar supplemented with Haemin b)Culture on McCoy cells

c) Culture on a bilayer human blood agar d)Culture on vero cell lines

11. A patient of Acute lymphocytic leukemia with fever and neutropenia develops diarrhoea after administration of amoxicillin therapy, which of the following organism is most likely to be causative agent?

a)Salmonella typhi

b)Clostridium difficile

c) Clostridium perfringens

d)Shigella flexneri

12. Which characteristic is NOT considered to have been a key character in early primate evolution? a)eyes adapted for discerning color and shape in a three-dimensional field

b)body and limbs adapted for tree climbing c) greater jaw and dental specialization d)eyes adapted for discerning movement in a three-dimensional field

13. In which group are retention of larval characteristics and sexual maturity seen in the same body? a)toads

b)Salamanders c) Frogs d)Caecilians

14. In vertebrate evolution, the appearance of the vertebral column led most directly to the development of which organs or functions? a)limbs such as arms and legs b)jaws c) greater speed and agility d)more efficient breathing system

15. Which of the following is a diagnostic feature of the sea squirts that forms the basis for its classification?

a)metamorphosis from a motile larva to a sessile adult b) a heart that allows circulation of blood c) a notochord located in the tail of the larva d) sexual reproduction during the larval stage

16. Which group is most closely related phylogenetically to the first vertebrates?

a)echinoderms b) arthropods c) annelids d) nematodes

17. Most biologists agree that seaweeds are protists, even though most other protists are microscopic unicellular creatures. Some biologists think that at least some seaweed should be considered plants, not protists. Which of the following would support the latter position?

a)Certain seaweeds contain several kinds of specialized cells.

b)Certain seaweeds undergo sexual and asexual reproduction

c) Certain seaweeds are found to be prokaryotic d)Certain seaweeds have very complex cells

18. Some biologists study the complex interactions of animals and plants in forests or prairies. Such ecology field research often produces slightly different results for different researchers. In contrast, ecology experiments that are run indoors with one organism in a terrarium usually produce results that are repeatable. What is the most likely explanation?

a)The scientific method is only useful in laboratory settings

b)It is not possible to establish a control group outside of a laboratory c) It is easier to hold all but one variable constant in a laboratory d)Field research is only descriptive, and descriptive research is not strictly "science."

What is the correct sequence of the following four events during

With the current molecular-based phylogeny in mind, rank the

All of the following are reasonable hypotheses for the high

Which of the following conditions is the most likely indicator of a metapopulation’s long-term survival?

a) The population is not subdivided into subpropulations

b) Regular and extensire movement of individuals among patches makes the subpopulations function essential as a single unit

c) Source and sinks all contain subpopulations

d) All subpopulations are connected by corridors

23. If the current molecular evidence regarding animal origins is well substantiated in the future, then what will be true of any contrary

evidence regarding the origin of animals derived from the fossil record?

a) The contrary fossil evidence will be seen as a hoax

b) The fossil evidence will be understood to have been incorrect because it is incomplete

c) The fossil record will henceforth be ignored

d) Phylogenies involving even the smallest bit of fossil evidence will need to be discarded.

24. Which of the following is descriptive of protostomes?

a) spiral and determinate cleavage, blastopore becomes mouth

b) spiral and indeterminate cleavage, blastopore becomes mouth c) spiral and determinate cleavage, blastopore becomes anus d) radial and determinate cleavage, blastopore becomes mouth

25. An obsolete taxon, the "Radiata," included all phyla whose adults had true radial symmetry. Today, the "Radiata" is more correctly considered to be

1. a clade.

2. a grade.

3. monophyletic.

4. paraphyletic.

5. polyphyletic.

a) 1 and 2

b) 1 and 3

c) 1, 2, and 3

d) 2 and 4

26. Mitochondria are thought to be the descendants of certain alpha proteobacteria. They are, however, no longer able to lead independent lives because most genes originally present on their chromosome have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes?

a)plasmolysis

b)conjugation

c) translation

d)horizontal gene transfer

27. A fish that has been salt-cured subsequently develops a reddish color. You suspect that the fish has been contaminated by the extreme halophile, Halobacterium. Which of these features of cells removed from the surface of the fish, if confirmed, would support your suspicion?

1. the presence of the same photosynthetic pigments found in cyanobacteria

2. cell walls that lack peptidoglycan

3. cells that are isotonic to conditions on the surface of the fish

4. cells containing bacteriorhodopsin

5. the presence of very large numbers of ion pumps in its plasma membrane

a)3 and 4

b)1, 2 and 5 c) 3, 4 and 5 d)2, 3, 4, and 5

28. The predatory bacterium, Bdellovibrio bacteriophorus, drills into a prey bacterium and, once inside, digests it. In an attack upon a gram-negative bacterium that has a slimy cell covering, what is the correct sequence of structures penetrated by B. bacteriophorus on its

The closest living relative of P. chromatophora is the heterotroph, P. ovalis. P. ovalis uses threadlike pseudopods to capture its prey, which it digests internally. Which of the following, if observed, would be the best reason for relabeling P. chromatophora as a mixotroph?

a pigmented central vacuole, surrounded by a tonoplast

The genome of modern chloroplasts is roughly 50% the size of the genome of the cyanobacterium from which it is thought to have been derived. In comparison, the genome of P. chromatophora's cyanelle is only slightly reduced relative to the size of the genome of the cyanobacterium from which it is thought to have been derived. What is a valid conclusion that can be drawn from this comparison? Lytic phage infections have targeted the chloroplast genome more

P. chromatophora's cyanelle is the result of an evolutionarily recent endosymbiosis

c) The genome of the chloroplast ancestor contained many more introns that could be lost without harm, compared to the cyanelle's genome

d)Two of the conclusions above are valid

31. A botanist discovers a new species of land plant with a dominant sporophyte, chlorophylls a and b, and cell walls made of cellulose. In assigning this plant to a phylum, which of the following, if present, would be least useful?

a)endosperm

b)seeds

c) spores

d)sperm that lack flagella

32. Given the differences between angiosperms and gymnosperms in the development of the integument(s), which of these statements is the most logical consequence?

a)The seed coats of angiosperms should be relatively thicker than those of gymnosperms

b)It should be much more difficult for pollen tubes to enter angiosperm ovules than for them to enter gymnosperm ovules

c) The female gametophytes of angiosperms should not be as well protected from environmental stress as should those of gymnosperms

d)As a direct consequence of such differences, angiosperms should have fruit.

33. The fruit of the mistletoe, a parasitic angiosperm, is a oneseeded berry. In members of the genus Viscum, the outside of the seed is viscous (sticky), which permits the seed to adhere to surfaces, such as the branches of host plants or the beaks of birds. What should be expected of the fruit if the viscosity of Viscum seeds is primarily an adaptation for dispersal rather than an adaptation for infecting host plant tissues?

a)It should be drab in color

b)It should be colored so as to provide it with camouflage

c) It should be nutritious

d)It should secrete enzymes that can digest bark

34. On the Pacific island of Guam, large herbivorous bats called "flying foxes" commonly feed on cycad seeds, a potent source of neurotoxins. The flying foxes do not visit male cones. Consequently, what should be true?

a)Flying foxes can be dispersal agents of cycad seeds if the seeds sometimes get swallowed whole (in other words, without getting chewed).

b)The flying foxes assist the beetles as important pollinating agents of

Flying foxes are highly susceptible to the effects of the neurotoxins. The flying foxes are attracted to cycad fruit, and eat the enclosed

If the current molecular evidence regarding animal origins is well-substantiated in the future, then what will be true of any contrary evidence regarding the origin of animals derived from the

The fossil evidence will be understood to have been incorrect because

Phylogenies involving even the smallest bit of fossil evidence will

Glossary Glossary

Abdomen: The third section of the insect body, including the digestive and reproductive organs and most of the circulatory and respiratory systems.

Adult: The fully developed and sexually mature stage in an organism’s life cycle.

Alga (algae,.): Algae are aquatic protists containing chlorophyll. They may be microscopic and unicellular or huge and multicellular. Amoeba (amoebae): found in decaying organic material at the bottom of bodies of freshwater.

Anther: The part of the stamen (at the tip) where pollen is produced.

Aquatic: Living or occurring in water. Bacterium (bacteria,): a nucleus and organelles (prokaryotic). Bacteria are found in all environments and most are harmless to humans.

Cell: The basic unit of life. All organisms are cells or are made of cells.

Cell membrane: separating it from its environment.

Cell wall: A semirigid structure that surrounds cells of plants, fungi, and bacteria.

Chlorophyll: A green pigment in chloroplasts that captures light energy, which is used to make food.

Chloroplast: An organelle containing chlorophyll found in plant cells and some protists.

Cotyledon: The white, starchy part of a seed. The cotyledon contains food to nourish the embryo during germination. Cilium (cilia,): their fluid environment.

Cuticle: A waxy layer on the outside of plant cell walls that reduces water loss through evaporation.

Cytoplasm: The fluid portion of a cell’s interior. The organelles are suspended in the cytoplasm.

Dormant: A state of suspended biological activity. Dormant organisms are alive but inactive. Ectotherm: An animal whose body temperature is the same as its environment.

Egg: The female sex cell.

Elodea: Aquatic plant with translucent leaves that grows in freshwater ponds and slow-moving streams throughout North America.

Embryo: The early developmental stage of a plant or animal. Energy: The capacity to do work. Most of the energy used by living organisms comes from the Sun. Epidermis: The outermost layer of an organism. In humans it is composed of skin cells. In plants it is the outer layer of cells.

Estivate: A dormant or torpid state brought on by hot, dry conditions, similar in some ways to hibernation.

Eukaryotic: Cells that contain a nucleus and organelles. All cells, except bacteria, are eukaryotic.

Exoskeleton: A rigid outer covering that supports some soft-tissued organisms, such as insects.

Fertilization: The union of the nucleus of an egg cell with the nucleus of a sperm cell to produce a cell that will divide to become a new organism of the same type as the parent cells.

Flagellum (flagella,): A whiplike structure that propels protests

In a microscope, the focal plane is a flat region parallel to the microscope slide where the image of the specimen is in focus. The focal plane always stays at a specific distance from the objective

A substance that provides nutrients for organisms. Photosynthetic organisms produce their own food; all other organisms must consume food. Food is used by organisms for growth, repair,

The ripened ovary of a plant containing the seeds.

One of the five kingdoms of life, fungi are always composed of eukaryotic cells. Fungi, including molds, mushrooms, and yeasts, can be single cell or multicellular. They digest food externally

Gas exchange is one of the characteristics of all organisms. Gas exchange occurs at the cellular level with carbon dioxide, oxygen, and water vapor being the most common gases

Snails and slugs are members of this class, which comprises the largest group of animals in phylum Mollusca. The name

The start of growth and development of a seed. Increase in size of an organism. Growth is characteristic of

A specialized epidermal plant cell that controls the opening and closing of the stomates, thus regulating transpiration. The place where an organism lives and gets what it needs

A condition of an organism that has both male and female sexual reproduction organs, producing both eggs and sperm.

Insect: One of the classes of animals in the phylum Arthropoda. Most insects have three body parts (head, thorax, and abdomen), six legs,

Kingdom: A taxonomic category grouping together all forms of life that share fundamental characteristics. In this course we use the fivekingdom system for categorizing all living things (Monera, Protista, Fungi, Plantae, Animalia.)

Larva: The immature, wingless, feeding stage in the life cycle of many insects.

Metamorphosis, complete: The life cycle of some insects that progresses from egg, to larva, to pupa, and finally to adult. Metamorphosis, incomplete: The life cycle of some insects that progresses from egg, to a number of nymphal stages, and finally to adult. Different insects have different numbers of nymphal stages.

Mitochondrion: A cell organelle that processes sugar, providing energy for the cell and releasing simple chemicals into the cell cytoplasm.

Monera: One of the five kingdoms of life. Organisms in this kingdom are all prokaryotic cells called bacteria.

Nucleus: This cell organelle regulates the production of proteins and contains genetic material.

Organelle: Structure inside eukaryotic cells that performs specialized functions.

Organism: An individual living thing, such as a plant, animal, fungus, bacterium, or protist.

Ovary: The part of the plant at the base of the pistil that contains the egg. After fertilization the ovary turns into a fruit. Ovule: The potential seeds found within the ovaries of a plant.

Palisade layer: under the epidermis in many leaves. Paramecium (paramecia, pl.): water and eats other tiny organisms for food.

Pheromone: A chemical released by an animal to communicate with or influence another member of the same species.

Phloem: The tissue within a plant that transports food made in the leaves to all other parts of the plant. Photosynthesis: bacteria use light energy, carbon dioxide, and water to make sugar. Pistil: A part of a flower. It is the female reproductive structure. It consists of the ovary, containing the seeds, and the stigma. Pollen: The tiny particles that contain the male sex cells. Pollen develops on the anthers. The pollen must be transported to the pistil for fertilization to occur.

Pollination: The transfer of male pollen grains from the anther in one flower to the stigma on the female pistil in another flower. Prokaryotic: A primitive kind of cell containing no nucleus or organelles. All prokaryotic cells are organisms called bacteria.

Protista: One of the five kingdoms of life. This very diverse kingdom is made up of eukaryotic cells, most of which are single-celled organisms.

Pupa: One of the stages in the life cycle of insects that go through complete metamorphosis. The pupa is a nonfeeding, resting stage.

Radula: A tongue like structure containing rows of teeth in the mouths of most gastropods that is used for eating. Reproduction: individuals of their kind. Some reproduce asexually (without the joining of two cells) and others reproduce sexually (the joining of egg and sperm cells).

Response: All organisms are influenced by their environments. The things organisms do when they are influenced by the environment are called responses.

Root: The underground part of a plant that functions as an organ to take up water and minerals, store food, and anchor the plant.

Root hair: An extension of an epidermal cell near the root tip that takes in water and minerals.

Seed: A young plant in a dormant or resting stage, capable of growing into an adult plant.

Seed-dispersal mechanism: A structure or feature of a seed that allows it to be transported some distance from a parent plant.

Seed-dispersal strategy: A way that seeds can be transported away from the parent plant, such as wind or animals.

Sperm: The male sex cell.

An opening on the side of an insect that allows for gas exchange (oxygen enters and carbon dioxide exits). The spiracle is A ground tissue in

A part of a flower. It is the male reproductive structure. At the end of the long stamen is the anther where pollen grains form.

The stigma is the tip of the pistil that is often sticky and

An opening on the surface of a leaf. Carbon dioxide, oxygen, and water vapor pass in and out of the stomata. Guard cells

One type of chemical compound produced by plants as a result of photosynthesis. Sugars are sources of energy for living organisms. The science of classifying organisms based on

A soft sensory appendage used by animals to get information about the environment. Snails have tentacles. The middle body part of insects where legs and wings

The process by which water flows through plants,

A fluid-filled membrane in the cytoplasm of plant cells, fungus cells, and protist cells. In protists there are food vacuoles and

Solids, liquids, or gases that are unusable by the cells of

The vascular system within a plant (made of long connected cells) that transports water and minerals from the roots to the rest of

For Lecture Videos, PPTs and answer to questions, log on