THE LIVING WORLD CHAPTER 1
Chapter Outline
1.1
What is Living?
1.2 Diversity in the Living World
1.3 Taxonomic Categories
The marvels of the living world are truly remarkable! The astonishing variety of living organisms never fails to amaze. Whether nestled in the frigid peaks of mountains, the lush expanses of deciduous forests, the depths of oceans, the serene landscapes of freshwater lakes, the arid expanses of deserts, or the bubbling warmth of hot springs, the habitats where living entities thrive leave us utterly speechless. The grace of a galloping horse, the spectacle of migrating birds, the enchantment of a valley adorned with flowers, or the power of an attacking shark, all elicit a profound sense of awe and wonder.
Contemplating the ecological dynamics, the conflicts and cooperation among individuals within a population, the interactions among populations in a community, or even the intricate molecular activity within a cell prompts us to ponder: What, indeed, is the essence of life? This question harbours two underlying inquiries. The first is of a technical nature, aiming to discern the characteristics that differentiate the living from non-living entities. The second is more philosophical, delving into the purpose of life. As scientists, we abstain from delving into the latter, choosing instead to focus our reflections on the fundamental question: What defines something as living?
Ernst Mayr, born on July 5, 1904, in Kempten, Germany, was a renowned Harvard University evolutionary biologist known as ‘The Darwin of the 20 th century.’ Throughout his nearly 80year career, he significantly contributed to ornithology, taxonomy, zoogeography, evolution, systematics, and the history and philosophy of biology. He introduced the widely accepted definition of a biological species and made origin of species diversity the central question of evolutionary biology. He received prestigious awards, including the Balzan Prize in 1983, the International Prize for Biology in 1994, and the Crafoord Prize in 1999. Mayr passed away at the age of 100 in 2004.
1.1 WHAT IS LIVING?
When defining ‘living,’ we typically seek unique characteristics in organisms. Immediate considerations include growth, reproduction, and the ability to sense and respond to the environment. Additional features, such as metabolism, self-replication, self-organisation, interaction, and emergence,
can also be considered. Let’s delve into each of these aspects. Some features are considered as defining features when they are present unexceptionally in all living organisms, and these features are never present in any nonliving things.
1.1.1 Growth
Growth is a universal characteristic of living organisms. It involves an increase in both the masses and the number of individuals.
Multicellular organisms achieve growth through cell division. There is continuous growth in plants ( indeterminate growth ) and limited growth in animals ( determinate growth). Unicellular organisms also grow by cell division, which is easily observed in in vitro cultures by simply counting the number of cells under a microscope.
In higher animals and plants, growth and reproduction are often mutually exclusive events.
Increase in body mass defines growth, but this criterion is not exclusive to living organisms. Non-living objects, like mountains, boulders, and sand mounds, can also ‘grow’ by accumulating material externally (extrinsic growth). Growth in living organisms originates from within (intrinsic growth), distinguishing it from non-living growth. Growth ceases in dead organisms.
While growth is a characteristic of living systems, it is not a defining property, as certain non-living entities can exhibit growth.
1.1.2 Reproduction
Reproduction is a key characteristic of living organisms. In multicellular organisms, reproduction involves producing progeny with features more or less similar to their parents, invariably and implicitly referring to sexual reproduction.
Asexual reproduction is common in fungi, facilitated by the production of numerous
asexual spores. Lower organisms, like yeast and Hydra, exhibit budding, while Planaria demonstrate true regeneration , regrowing lost body parts to form a new organism. Fragmentation is a method of reproduction in fungi, filamentous algae, and the protonema of mosses.
Unicellular organisms, like bacteria, unicellular algae, or Amoeba , equate reproduction with growth, involving an increase in cell number. The terms ‘growth’ and ‘reproduction’ are less distinct in singlecelled organisms. In a unicellular organism, growth and reproduction are mutually inclusive events.
Some organisms, such as mules, sterile worker bees, and infertile human couples, do not reproduce, highlighting that reproduction is not a universal defining characteristic. Non-living objects lack the capacity for reproduction or replication.
1.1.3 Metabolism
Metabolism is a crucial characteristic of life. Living organisms, comprising chemicals of various classes, constantly undergo chemical reactions, forming and transforming biomolecules.
Metabolic reactions, whether small or large, occur in all living organisms, both unicellular and multicellular. Plants, animals, fungi, and microbes, all exhibit metabolism. Metabolism encompasses the sum of chemical reactions within an organism’s body and no non-living object displays metabolism.
Metabolic reactions can be demonstrated outside the body in cell-free systems, but these reactions, when isolated in a test tube, are neither living nor non-living— they are living reactions.
While metabolism is a defining feature of all living organisms, the cellular organisation of the body is the ultimate defining characteristic of life forms.
1.1.4 Consciousness
The ability to sense and respond to the environment is a distinctive and complex feature of all living organisms.
Living organisms, from prokaryotes to complex eukaryotes, can detect and respond to environmental stimuli, including physical, chemical, and biological cues.
Sense organs enable organisms, including humans, to perceive their surroundings. Plants respond to external factors, like light, water, temperature, and other organisms. Environmental cues, such as photoperiod, influence reproduction in seasonal breeders among both plants and animals. All organisms exhibit awareness of their surroundings and respond to chemicals entering their bodies.
Human beings possess self-consciousness, making consciousness a defining property of living organisms. Consciousness distinguishes living organisms from non-living entities and becomes a key characteristic of life.
Defining the living state becomes complex in the case of human beings. In hospitals, we witness patients in a coma, sustained by machines replacing vital functions. Despite external support, some patients, being braindead and lacking self-consciousness, pose a challenge to categorise them as living or non-living, especially if they do not recover to normal life.
Tissue properties arise from interactions among constituent cells, while organelle properties result from interactions among molecular components. These interactions lead to emergent properties at higher organisational levels. Living organisms, as self-replicating, evolving, and self-regulating interactive systems, respond to external stimuli. Biology narrates the story of life’s evolution on Earth, connecting all living organisms through shared genetic material to varying degrees.
Checkpoint
Q. Though reproduction is a characteristic of only living organisms, why is it not considered a defining feature?
Though reproduction is a characteristic of only living organisms, there are a few living organisms that are sterile and, hence, cannot reproduce, e.g., sterile human couples, mules, etc. Hence, reproduction is not a defining feature of living organisms.
Answer:
TEST YOURSELF
1. Permanent increase in mass of living organisms is termed as (1) growth (2) reproduction
(3) consciousness (4) metabolism
2. Growth cannot be taken as a defining property of living organisms as (1) it is found in all living organisms (2) it is found in non-living things also (3) all non-living things grow (4) it is discontinuous
3. A true regeneration is observed in (1) Hydra (2) sponges
(3) Planaria (4) fungi
4. Sum total of all the chemical reactions occurring in the body of an organism is called
(1) anabolism
(2) catabolism
(3) metabolism
(4) isolated chemical reaction
5. Metabolic reactions do not take place in (1) non-living things
(2) living systems
(3) isolated cell-free systems
(4) a virus-infected living organism
6. What is the most obvious and technically complicated feature of living organisms by which they sense the surroundings?
(1) Growth (2) Consciousness
(3) Metabolism (4) Reproduction
Answer Key
(1) 1 (2) 2 (3) 3 (4) 3
(5) 1 (6) 2
1.2 DIVERSITY IN THE LIVING WORLD
In our vicinity, diverse macroscopic organisms, such as potted plants, insects, birds, and other animals, are observed, alongside numerous microscopic organisms invisible to the naked eye. Dense forests harbour an even greater variety of living organisms, with each distinct plant, animal, or organism representing a species. The total number of known and described species ranges from 1.7 to 1.8 million, encapsulating Earth’s biodiversity. As scientists explore both new and familiar locations, the continuous identification and listing of new organisms contribute to our understanding of biodiversity.
Millions of plants and animals exist globally, known locally by different names. To avoid confusion, standardising the naming of living organisms worldwide is crucial. This standardisation is known as nomenclature . Clearly, nomenclature is contingent upon accurate description of the organism and knowing to which organism the name corresponds— essentially, the process of identification . Scientists use established procedures and international codes— such as the International Code for Botanical Nomenclature (ICBN) for plants and the International Code of Zoological Nomenclature (ICZN) for animals— to assign unique scientific names. These names ensure consistency and avoid duplication, allowing people worldwide to refer to the same organism using a universally recognised name.
Biologists adhere to universally accepted principles when assigning scientific names to known organisms. Each name comprises two components— the generic name and the specific epithet. This system, known as binomial nomenclature, was introduced by Carolus Linnaeus, and is widely practiced worldwide. Let’s use the example of the mango to gain a clearer understanding of how scientific names are assigned.
Universal rules for binomial nomenclature:
1. Biological names are typically in Latin and are presented in italics. They are Latinised or derived from Latin, regardless of their origin.
2. The first word in a biological name indicates the genus, while the second component denotes the specific epithet. The scientific name of mango is Mangifera indica, where Mangifera is the genus and indica is the specific epithet.
3. When handwritten, both words in a biological name are separately underlined.
4. In print form, the names are represented in italics to signify their Latin origin.
5. The first word representing the genus always starts with a capital letter, while the specific epithet starts with a lowercase letter, for example, Mangifera indica
6. Following the specific epithet, the name of the author appears in an abbreviated form, indicating who first described the species. For instance, Mangifera indica Linn. denotes that Linnaeus first described this species.
7. A scientific name with the same word used for the genus and species is termed a tautonym , e.g., Naja naja. However, tautonyms are invalid only for botanical names.
8. In cases where two or more names are given, the oldest name (given first) is
recognised as the valid name (rule of priority). Subsequent names for the same taxon are considered synonyms . For instance, Phaseolus aureus is recognised as valid, while Vigna aureus is considered a synonym. Additionally, if a name is the same for both a species and a subspecies, it is called an autonym (e.g., Corvus splendens splendens).
Since studying all living organisms is nearly impossible, a necessary process is devised to make classification feasible. Classification involves grouping things into convenient categories based on easily observable characteristics. For instance, we readily recognise groups like plants, animals, or specific animals, like dogs, cats, or insects. Each term we use for these groups is associated with certain characteristics of the organisms within them. For example, when thinking of a dog, we all conjure an image of a dog, not a cat. Similarly, terms like ‘Alsatians’ or ‘mammals’ evoke specific images and associations.
In the plant kingdom, mentioning ‘wheat’ brings to mind wheat plants, not rice or any other plant. All these terms, such as ‘dogs,’ ‘cats,’ ‘mammals,’ ‘wheat,’ ‘rice,’ ‘plants,’ and ‘animals,’ serve as convenient categories for studying organisms. The scientific term for these categories is taxa. It’s important to recognise that taxa can indicate categories at various levels. For instance, ‘plants’ and ‘wheat’ are both taxa, and so are ‘animals,’ ‘mammals,’ and ‘dogs.’ However, understanding that a dog is a mammal, and mammals are animals, illustrates that these terms represent taxa at different hierarchical levels.
Therefore, based on characteristics, all living organisms can be classified into different taxa, and this process is known as taxonomy The external and internal structure, cell structure, development process, and ecological information of organisms are essential and form the foundation of modern taxonomic studies.
Characterisation, identification, classification, and nomenclature are fundamental processes in taxonomy.
Throughout history, humans have not only sought to understand different organisms and their diversities but also their relationships. This field of study was referred to as systematics , a term derived from the Latin word ‘systema,’ signifying the systematic arrangement of organisms. Linnaeus used ‘Systema Naturae’ as the title of his publication. Systematics initially focused on systematic arrangement but was later broadened to include identification, nomenclature, and classification. Importantly, systematics considers the evolutionary relationships between organisms.
Checkpoint
Q. What problems could arise if scientists did not use binomial nomenclature, and each organism had multiple common names in different languages?
Binomial nomenclature, using Latin, offers a concise, precise, and globally recognised system for naming and categorising organisms, addressing these challenges.
Answer: Without binomial nomenclature and with multiple common names in different languages, issues like confusion, lack of standardisation, imprecision in scientific communication, and lack of international collaboration and taxonomic clarity arise.
TEST YOURSELF
1. The science of naming organisms is called
(1) identification
(2) nomenclature
(3) classification
(4) taxonomy
2. Linnaeus evolved a system of nomenclature called
(1) trinomial nomenclature (2) vernacular nomenclature (3) binomial nomenclature (4) polynomial nomenclature
3. The two components of binomial nomenclature are (1) genus and author (2) family and genus (3) genus and species (4) species and author
4. What is the correct way of representing a biological authentic name as per the rules of nomenclature?
(1) APIS INDICA
(2) Trypanosoma gambiense
(3) Ficus Benghalensis
(4) Mangifera indica
5. Arrangement of organisms into convenient categories on the basis of similarities and differences in certain easily observable but fundamental characters is
(1) taxonomy (2) classification
(3) nomenclature (4) identification
Answer Key
(1) 2 (2) 3 (3) 3 (4) 4 (5) 2
1.3 TAXONOMIC CATEGORIES
Classification is not a single-step process; instead, it involves a hierarchy of steps where each step represents a rank or category. These categories, integral to the overall taxonomic arrangement, are known as taxonomic categories, and collectively, they form the taxonomic hierarchy. Each category, considered a unit of classification, essentially signifies a rank and is commonly referred to as a taxon (plural: taxa).
The concept of taxonomic categories and hierarchy becomes apparent through examples. Insects, for instance, form a distinct group characterised by shared features, such as three pairs of jointed legs. This characteristic makes insects identifiable and classifiable. Keep in mind that these groups signify specific categories, and each category corresponds to a particular rank in the taxonomic hierarchy. Every rank or taxon serves as a fundamental unit of classification. It is important to note that these taxonomic groups or categories represent cohesive biological entities, not merely collections of morphological traits.
The taxonomic exploration of all known organisms resulted in the establishment of standardised categories, including kingdom, phylum (or division for plants), class, order, family, genus, and species. [Fig. 1.1]
Kingdom
Phylum or Division
Class
Family
Genus
Species Order
Fig. 1.1 Taxonomic categories showing hierarchical arrangement in ascending order (from top to bottom)
Notably, all organisms, spanning both the plant and animal kingdoms, are categorised
into species a t the lowest level. Placing an organism in different categories requires understanding its characteristics, facilitating the identification of similarities and differences within and across species.
1.3.1
Species
Ernst Mayr’s b iological concept of species defines a species as a group of organisms closely related both structurally and functionally, sharing a common gene pool. This group can freely interbreed in nature, producing fertile offspring in a natural environment. This biological species concept is rooted in the idea of reproductive isolation.
Species, in taxonomic studies, refers to a group of individual organisms sharing fundamental similarities. Distinguishing closely related species relies on discerning distinct morphological differences. For instance, Mangifera indica , Solanum tuberosum (potato), and Panthera leo (lion) exemplify this concept. In these names, ‘ indica ,’ ‘ tuberosum ,’ and ‘ leo ’ are specific epithets, while ‘ Mangifera ,’ ‘ Solanum ,’ and ‘Panthera’ are genera, representing a higher taxonomic level. Each genus may encompass multiple specific epithets, signifying different organisms with morphological similarities. For example, Panthera includes another specific epithet, ‘tigris,’ and Solanum includes species like ‘nigrum’ and ‘melongena.’ Human beings belong to the species ‘sapiens,’ grouped under the genus Homo. Therefore, the scientific name for humans is written as ‘ Homo sapiens.’
1.3.2
Genus
The term ‘genus’ refers to a grouping of closely related species that share more common characteristics with each other than with
species from other genera. In other words, genera are collections of closely related species. For instance, potato and brinjal are distinct species but belong to the same genus, Solanum Similarly, lion ( Panthera leo ), leopard (P. pardus), and tiger (P. tigris), despite being different species, share common features and belong to the genus Panthera. This genus is distinct from another genus, Felis , which encompasses various species of cats.
1.3.3 Family
The next taxonomic category, family, represents a grouping of related genera, with fewer similarities compared to genus and species. Families are identified based on both vegetative and reproductive features of plant species. For instance, in the plant kingdom, the family Solanaceae includes three different genera: Solanum, Petunia, and Datura . In the animal kingdom, the family Felidae encompasses the genus Panthera (lion, tiger, leopard) and the genus Felis (cats). Similarly, when comparing features of a cat and a dog, some similarities and differences are observed, leading to their classification into two different families— Felidae and Canidae, respectively.
1.3.4 Order
As we move to higher taxonomic categories, such as order, the identification is based on aggregates of characters. Orders are assemblies of families that share a few common characteristics. Although the number of similar characters is fewer compared to different genera within a family, these shared traits help distinguish and group families together. For example, plant families like Convolvulaceae and Solanaceae are included
in the order Poly moniales, primarily based on floral characters. Similarly, in the animal kingdo m, the order Carnivora includes families like Felidae and Canidae, where certain common characteristics unite them at a higher taxonomic level.
1.3.5 Class
In the taxonomic hierarchy, a class is a rank or category that groups together related orders. For instance, the order Primata, which includes monkeys, gorillas, and gibbons, is placed in the class Mammalia. Similarly, the order Carnivora, encompassing animals like tigers, cats, and dogs, is also placed in the class Mammalia. Class Mammalia further includes additional orders, showcasing the hierarchical organisation of taxonomic groups.
1.3.6 Phylum/Division
A phylum is a rank or category that groups together related classes. Classes, which include animals such as fishes, amphibians, reptiles, birds, and mammals, collectively form the next higher taxonomic category, known as phylum. All these classes, characterised by common features, like the presence of a notochord and a dorsal hollow neural system, are included in the phylum Chordata. In plants, classes with a
few shared characteristics are grouped into a higher taxonomic category, known as division.
1.3.7 Kingdom
All animals, categorised into different phyla, are placed in the highest taxonomic category, known as Kingdom Animalia. In contrast, Kingdom Plantae encompasses all plants from various divisions. Henceforth, we’ll refer to these groups as the animal and plant kingdoms.
The taxonomic categories from species to kingdom, displayed in ascending order, represent broad classifications. Taxonomists have also introduced sub-categories within this hierarchy to ensure a more precise and scientifically sound placement of various taxa.
As we ascend from species to kingdom, the number of shared characteristics decreases. Lower taxa, such as species, exhibit more common traits among their members. In contrast, higher taxonomic categories pose greater challenges in determining relationships with other taxa at the same level. Consequently, the problem of classification becomes more intricate at higher levels of the taxonomic hierarchy. Table 1.1 indicates the taxanomic categories to which some common organisms like man, housefly,mango and wheat belong.
Suffixes are used for various taxa:
■ For division, -phyta is used.
■ For class, -opsida, -phyceae, -ae are used.
■ For order, -ales is used.
■ For family, -aceae is used.
We do not use any suffix for genus and species.
Checkpoint
1. Which taxonomic category is broader than a family but narrower than a class?
2. What is the primary criterion used for grouping organisms into the same species?
2. The ability to interbreed and produce fertile offspring
1. Order
Answers:
TEST YOURSELF
1. A taxon is
(1) a group of related genera
(2) a group of related species
(3) a group of related categories
(4) a taxonomic group of any rank
2. The correct sequence of taxa is
(1) Class – order – family – species – genus
(2) Class – family – order – species – genus
(3) Phylum – order – class – species – genus
(4) Phylum – class – order – genus – species
CHAPTER REVIEW
What is Living?
3. Basic unit or smallest taxon of classification is
(1) species (2) kingdom (3) family (4) variety
4. A group of closely related organisms capable of interbreeding to produce fertile offspring are kept in the same (1) order (2) family (3) genus (4) species
5. Which taxonomic category has a group of related genera?
(1) Family (2) Species (3) Order (4) Class
6. What is the common taxonomic category for Petunia, mango, and makoi?
(1) Order (2) Genus (3) Family (4) Class
7. Triticum aestivum belongs to division (1) Gymnospermae (2) Monocotyledonae (3) Angiospermae (4) Dicotyledonae
8. In the taxonomic hierarchy, as we go higher from species to kingdom, the number of common characters (1) keep on increasing (2) keep on decreasing (3) remain the same (4) remain constant
Answer Key
(1) 4 (2) 4 (3) 1 (4) 4 (5) 1 (6) 4 (7) 3 (8) 2
■ Grow th is a universal characteristic involving an increase in mass and number of individuals. Growth can be intrinsic (from within) or extrinsic (external accumulation) growth. Growth is not exclusive to living organisms; certain nonliving entities can exhibit growth.
■ Reproduction is a key characteristic involving the production of progeny with
features similar to parents. Reproduction can be sexual or asexual. Reproduction is not universal; some organisms do not reproduce.
■ Metabolism is a crucial characteristic involving constant chemical reactions in living organisms. Metabolism occurs in all living organisms, distinguishing them from non-living entities. Metabolic reactions outside the body are neither living nor non-living.
■ Consciousness is a distinctive feature involving the ability to sense and respond to the environment. Self-consciousness is present only in human beings.
■ Tissue properties result from interactions among cells, while organelle properties result from molecular interactions.
Diversity in the Living World
■ Ea rth’s biodiversity includes both macroscopic and microscopic organisms.
■ Ernst Mayr’s biological species concept emphasises structural and functional relationships with reproductive isolation.
■ Standardised naming (nomenclature) is crucial for global clarity.
■ Binomial nomenclature (two-part naming system) was introduced by Linnaeus.
■ Rules for naming include Latin usage and italics while it is printed, underlining when handwritten, and capitalisation of the first letter of genus.
■ Terms like ‘plants’ and ‘wheat’ represent taxa at different hierarchical levels.
■ Taxonomy involves classifying organisms based on characteristics like structure, cell structure, development, and ecology.
■ Systematics, derived from ‘systema,’ involves the systematic arrangement, identification, nomenclature, and
classification of organisms.
■ Originally focused on arrangement, systematics now includes evolutionary relationships between organisms.
Taxonomic Categories
■ Classi fication is a hierarchical process involving ranks or categories, called taxonomic categories.
■ Taxa collectively form the taxonomic hierarchy, and each represents a unit of classification.
■ Standardised categories include kingdom, phylum, class, order, family, genus, and species.
■ Carl Woese introduced the domain as the broadest taxon.
■ Species refers to a group of organisms sharing fundamental similarities.
■ Genus groups closely related species sharing common characteristics. Genus Solanum includes potato and brinjal, while Panthera includes lion, leopard, and tiger.
■ Family groups related genera with fewer similarities compared to genus and species. Plant family Solanaceae includes genera Solanum, Petunia, and Datura.
■ Order assembles families based on shared characteristics. Order Polymoniales includes plant families Convolvulaceae and Solanaceae.
■ Class groups related orders, showcasing hierarchical organisation. Class Mammalia includes orders Primata and Carnivora.
■ Phylum groups related classes. Division is used for plants.
■ Kingdom Animalia includes animal phyla. Kingdom Plantae encompasses plant divisions.
■ As we ascend from species to kingdom, shared characteristics decrease. Higher taxonomic categories pose challenges in determining relationships at the same level.
NEET DRILL
Introduction to Living World
1. The references given below are associated with which scientist?
(a) The Darwin of the 20th century
(b) Alexander Agassiz, professor of Zoology Emeritus
(c) Awarded the triple crown of Biology
(1) Carolus Linnaeus
(2) Ernst Mayr
(3) Theophrastus
(4) Aristotle
2. Which of the following is the correct sequence in the increasing order of complexity?
(1) Molecule, tissue, community, population
(2) Cell, tissue, community, population
(3) Tissue, organism, population, community
(4) Molecule, tissue, community, cells
3. Mayer’s biological concept of species is mainly based on (1) morphological traits
(2) reproductive isolation
(3) modes of reproduction
(4) morphology and reproduction
4. Inanimate matter includes all except (1) wind (2) sea
(3) fire (4) plants and animals
What is Living
5. Growth in living being occurs by (1) cell division
(2) accumulation on surface only (3) reductional division only (4) cell death
6. Growth can be treated as a defining property of living organisms, if it takes place by (1) intrinsic methods
(2) accumulation of materials on surface
(3) cell division as well as accumulation of materials
(4) increase in fresh weight only
7. Growth and reproduction are mutually exclusive events in (1) all unicellular organisms
(2) majority of higher animals and plants
(3) most unicellular organisms
(4) all lower plants and animals
8. Growth is not considered as a defining property of living organisms because (1) non-living entities also grow by accumulation of material on its body surface.
(2) reproduction and growth are same for multicellular organisms.
(3) dead organism does not grow.
(4) plants exhibit extrinsic growth.
9. Reproduction is synonymous with growth in which of the following set of organisms?
(1) Bacteria, unicellular algae and Amoeba
(2) Bacteria, Amoeba and fungi
(3) Unicellular algae and fungi
(4) Unicellular algae and multicellular algae
10. The twin characteristics of growth are (1) increase in number and increase in mass
(2) increase in height and decrease in weight
(3) increase in weight and decrease in mass
(4) increase in size and decrease in mass
11. Which character of living organism enables continuity of species, generation after generation?
(1) Growth
(2) Reproduction
(3) Metabolism
(4) Consciousness
12. Which of the following organisms do not reproduce?
(a) Mules
(b) Sterile worker bees
(c) Infertile human couples
(1) a and b only (2) b and c only
(3) c and d only (4) a, b and c
13. Organisms that reproduce by budding are
(1) algae
(2) Hydra
(3) Amoeba
(4) Pencillium
14. Which of the following set multiply by fragmentation?
(1) Ascaris, amoeba and fungi
(2) Earthworm, fungi and bacteria
(3) Fungi, filamentous algae and protonema of mosses
(4) Paramoecium, Hydra and bacteria
15. Select the incorrect statement for reproduction.
(1) It is not an all-inclusive defining characteristic of living organisms.
(2) Photoperiod affects reproduction in seasonal breeders, both plants and animals.
(3) Photoperiod has no role in reproduction.
(4) Reproduction is absent in worker bees and mules.
16. All living organisms
(1) reproduce
(2) grow indefinitely
(3) exhibit metabolism
(4) possess sense organs
17. The sum total of chemical reactions occurring in our body is called
(1) metabolism
(2) homeostasis
(3) consciousness
(4) anabolism
18. Metabolic reactions do not take place in
(1) isolated cell-free systems with suitable enzymes.
(2) living systems.
(3) isolated cell-free systems without suitable enzymes.
(4) a virus outside a living organism.
19. Growth, development and functioning of living beings is due to (1) cell divisions
(2) homeostasis
(3) metabolism
(4) adaptations
20. The response to environmental stimuli is called
(1) metabolism
(2) irritability
(3) chemical reaction
(4) growth
21. Induction of flowering in plants by exposing them to a correct photoperiod comes under which of the following distinctive features of living organisms?
(1) Metabolism
(2) Consciousness
(3) Reproduction
(4) Growth
22. Select a set of defining properties of all living organisms.
(1) Consciousness and metabolism
(2) Growth and cellular organization
(3) Reproduction and growth
(4) Growth and consciousness
23. Which defining feature of of living organisms is not shown by a person in coma?
(1) Cell division
(2) Cellular organisation of body
(3) Metabolism
(4) Consciousness
24. Properties of tissues
(1) are present in the constituent cells
(2) are due to similar cells in them
(3) are due to their similar origin
(4) arise as a result of interactions among the constituent cells
Diversity in Living World
25. The diversity of living organisms refers to which of the following?
(1) Different forms of organisms
(2) The same form of organisms
(3) Different coloured organisms
(4) Different organisms based on habitat
26. Total number of species of living organisms known and described so far is
(1) 1.6 to 1.7 million (2) 1.7 to 1.8 billion
(3) 1.8 to 1.9 million (4) 1.7 to 1.8 million
27. Which amongst the following processes are basic components to taxonomy?
(a) Characterisation
(b) Identification
(c) Classification
(d) Nomenclature
(1) a, b and c only (2) b, c and d only
(3) a, c and d only (4) a, b, c and d
28. Providing a scientific name to the organism, that is same all over the world, is called
(1) classification (2) nomenclature
(3) identification (4) phylogeny
29. Nomenclature is governed by certain universal rules. Which one of the following is true as per rules of nomenclature?
(1) Biological names are usually given in latin language.
(2) The first word in a biological name represents the species name.
(3) The names are given in bold and italics and are latinised.
(4) When printed, the names are to be underlined.
30. Scientific names are printed in .... and are derived from ..........
(1) italics and english
(2) latin and italics
(3) italics and greek
(4) italics and latin
31. Branch of biology dealing with nomenclature, identification and classification of organisms isW
(1) ecology
(2) taxonomy
(3) morphology
(4) physiology
32. The word systematics is derived from ___A___ “systema” which means ___B___ arrangement of organisms.
(1) greek word beneficial
(2) latin word systematic
(3) latin word beneficial
(4) greek word systematic
Taxonomic Categories
33. In the taxonomic categories which hierarchical arrangement in descending order is correct in case of animals?
(1) Kingdom, Phylum, Class, Order, Family, Genus, Species
(2) Kingdom, Class, Phylum, Family, Order, Genus, Species
(3) Kingdom, Order, Class, Phylum, Family, Genus, Species
(4) Kingdom, Order, Phylum, Class, Family, Genus, Species
34. Choose the correct option for classification of mango plant by identifying taxa for I, II, and III.
Kingdom Plantae
Division Angiospermae
I Dicotyledonae
II Sapindales
Family III
I II III
(1) Genus Class Anacardiaceae
(2) Class Order Anacardiaceae
(3) Genus Class Solanaceae
(4) Class Order Poaceae
35. “nigrum” is a specific epithet for
(1) Mangifera
(2) Triticum
(3) Solanum
(4) Pisum
36. Which two members belong to the same genus but represents two different species?
(1) Potato and brinjal
(2) Cat and tiger
(3) Dog and lion
(4) Dog and cat
37. Lion, leopard and tiger represent
(1) different subspecies of same species
(2) different species of same genus
(3) different species of different genera
(4) same species
38. The common characters between cat and tiger are maximum at the level of (1) genus
(2) family
(3) order
(4) class
39. Polymoniales includes (1) related genera
(2) related species
(3) related families
(4) related orders
40. Felis + Panthera → A Solanaceae + Convolvulaceae → B
Identify A and B and choose the correct option
A B
(1) Canidae Poales
(2) Felidae Polymoniales
(3) Felidae Sapindales
(4) Canidae Polymoniales
41. Which of the following is more general in characters as compared to order?
(1) Family
(2) Class
(3) Genus
(4) Species
42. Presence of the notochord and dorsal hollow neural system, are the characteristic features of which phylum?
(1) Non-chordata
(2) Chordata
(3) Arthropoda
(4) Annelida
43. Choose the following taxa to form the correct sequence (from phylum to family) in classification of man.
(i) Primata (ii) Chordata
(iii) Mammalia (iv) Hominidae
(1) i → iii → iv → ii
(2) ii → iii → i → iv
(3) iv → ii → i → iii
(4) iii → ii → iv → i
44. Arrange the taxa of Musca domestica in descending order.
(A) Arthropoda
(B) Diptera
(C) Insecta
(D) Muscidae
Choose the correct answer.
(1) D → C → B → A
(2) A → B → C → D
(3) A → D → B → C
(4) A → C → B → D
45. Which of the following statements are correct?
(a) Groups of related genera make up a family.
FURTHER EXPLORATION
1. Tautonym is a
(1) non-scientific name
(2) colloquial word
(3) type of botanical nomenclature
(4) binomial name with identical genus and species epithets
2. Role of ICTV is
(1) classification of viruses
(2) classification of bacteria
(3) classification of all microbes
(4) classification of plants
3. A taxonomic category which is below the rank of species is
(b) Families are characterized on the basis of only vegetative features of plant species.
(c) Three different genera, Solanum, Petunia and Datura , are placed in the family Solanaceae.
(d) The genera Panthera and Felis are kept under the family Felidae.
(1) a, b and c only (2) b, c and d only
(3) a, c and d only (4) a, b and d only
46. Select the correct option to fill up the blanks:
(i) The higher the taxonomic category ____A____ is the number of organisms in it.
(ii) The higher the taxonomic category ____B____ is the number of common characters.
A B
(1) Higher Higher
(2) Lower Higher
(3) Lower Lower
(4) Higher Lower
(1) sub-species
(2) sub-population
(3) sub-variant
(4) sub-breed
4. The binomial nomenclature was first introduced by (1) CV Linnaeus (2) Endlicher (3) Gaspard Bauhin (4) Hutchinson
5. Father of taxonomy is
(1) De Candolle
(2) Haeckel
(3) Linnaeus
(4) Aristotle
MATCHING TYPE QUESTIONS
1. Match the column-I with column-II and choose the correct option.
Column-I Column-II
(A) Planaria (I) Binary fission
(B) Spirogyra (II) Budding
(C) Yeast (III) Fragmentation
(D) Amoeba (IV) True regeneration
(A) (B) (C) (D)
(1) I III II IV
(2) IV III II I
(3) IV III I II
(4) I II III IV
STATEMENT TYPE QUESTIONS
Each question has two statements: statement I (S-I) and statement II (S-II). Mark the correct answer as
(1) if both statement I and statement II are correct
(2) if both statement I and statement II are incorrect
(3) if statement I is correct but statement II is incorrect
(4) if statement I is incorrect but statement II is correct
1. S-I : An isolated metabolic reaction taking place outside the body of an organism is a living reaction and living thing.
S-II : The absorptive mode of nutrition in fungus involves secretion of enzymes on to the substrate, solubilize the food and absorb it.
2. S-I : All organisms from the prokaryotes to the most complex eukaryotes have the ability to sense their surroundings and respond to environmental stimuli.
2. Match the column-I with column-II and choose the correct option.
Column-I Column-II
(A) Family (I) tuberosum
(B) Kingdom (II) Polymoniales
(C) Order (III) Solanaceae
(D) Species (IV) Plantae
(A) (B) (C) (D)
(1) III IV II I
(2) III IV I II
(3) I II III IV
(4) II I III IV
S-II : Sense organs are not obligatory to all living systems, however humans have well-developed sense organs.
3. S-I : A seed germinates to give rise to a plant which in turn produce seed as it grows and adapts to environment.
S-II : Plants are self-replicating, evolving and self-regulating interactive systems capable of responding to external stimulus.
4. S-I : Consciousness is the most obvious and technically complicated feature of living organisms.
S-II : Living organisms could respond differently to the same stimulus.
5. S-I : The biological name of mango is written as Mangifera indica Linn.
S-II : The abbreviation Linn. indicates that this species was first described by Linnaeus.
6. S-I : Order Primata , which includes monkeys, gorillas and gibbons is placed in class Mammalia.
S-II : Order Carnivora, which includes animals like tigers, cats and dogs, is placed in class Mammalia.
7. S-I : Phylum Arthropoda includes the major portion of the animal species.
ASSERTION AND REASON QUESTIONS
In each of the following questions, a statement of Assertion (A) is given, followed by a corresponding statement of Reason (R). Mark the correct answer as
(1) if both (A) and (R) are true and (R) is the correct explanation of (A)
(2) if both (A) and (R) are true but (R) is not the correct explanation of (A)
(3) if (A) is true but (R) is false
(4) if both (A) and (R) are false
1. (A) : All living organisms of present, past and future are linked to one another by sharing the common genetic material.
(R) : The organisation of genetic material in all living organisms is of same type.
2. (A) : In Planaria we call regeneration as true regeneration.
FLASHBACK (Previous NEET Questions)
1. ‘X’ and ‘Y’ are the components of binomial nomenclature. This naming system was proposed by ‘Z’: (2023-M) X Y Z
(1) Generic name Specific epithet Carolus Linnaeus
(2) Specific epithet Generic name R.H. Whittaker
(3) Specific epithet Generic name Carolus Linnaeus
(4) Generic name Specific epithet R.H. Whittaker
S-II : In plants, classes with a few similar characters are assigned to a higher category called division.
8. S-I : Number of similar characters increase from kingdom to species.
S-II : Species diversity increases from species to kingdom.
(R) : A fragmented organism regenerates the lost part of its body and becomes a new organism in it.
3. (A) : No non-living object exhibits metabolism.
(R) : Cellular organisation is absent in non-living entities.
4. (A) : Higher the category greater is difficulty of determining relationship to other taxa at the same level.
(R) : From species to kingdom, the number of common characteristics goes on decreasing.
5. (A) : Taxonomists have also developed subcategories or intermediate taxonomic categories.
(R) : Sub-categories facilitate more sound and scientific placement of various taxa.
2. Study the four statements (A-D) given below and select the two correct ones out of them. (2023-M)
A. Definition of biological species was given by Ernst Mayr.
B. Photoperiod does not affect reproduction in plants.
C. Binomial nomenclature system was given by R.H. Whittaker.
D. In unicellular organisms, reproduction is synonymous with growth.
The two correct statements are
(1) B and C (2) C and D
(3) A and D (4) A and B
3. House fly belongs to _____ family. (2023-M)
(1) Cyprinidae (2) Hominidae
(3) Calliphoridae (4) Muscidae
4. Which of the following is against the rules of ICBN? (2019-O)
(1) Hand written scientific names should be underlined.
(2) Every species should have a generic name and a specific epithet.
(3) Scientific names are in Latin and should be italicized.
(4) Generic and specific names should be written starting with small letters.
5. Select the correctly written scientific name of Mango which was first described by Carolus Linnaeus. (2019)
(1) Mangifera lndica
(2) Mangifera indica Car.Linn
(3) Mangifera indica Linn.
(4) Mangifera indica
6. Match column-I with column-II for housefly classification and select the correct option. (2016-II)
Column-I
Column-II
(A) Family (I) Diptera
CHAPTER TEST
1. Growth in non–living objects is (1) extrinsic (2) intrinsic (3) localized (4) rapid
2. Growth is indeterminate due to the presence of meristems in (1) viruses (2) plants (3) animals (4) fungi
3. Which of the following statements regarding growth is incorrect?
(1) In animlas growth is seen up to certain age
(B) Order (II) Arthropoda
(C) Class (III) Muscidae
(D) Phylum (IV) Insecta
(A) (B) (C) (D)
(1) III I IV II
(2) III II IV I
(3) IV III II I
(4) IV II I III
7. Nomenclature is governed by certain universal rules. Which one of the following is contrary to the rules of nomenclature? (2016-I)
(1) The names are written in Latin and are italicised.
(2) When written by hand, the names are to be underlined.
(3) Biological names can be written in any language.
(4) The first word of biological name represents the genus name, and the second is a specific epithet.
8. The common characteristics between tomato and potato will be maximum at the level of their (2013-K)
(1) family (2) order
(3) division (4) genus
(2) Increase in body mass is considered as growth
(3) Growth by cell division occurs continuously throughout their span in animals
(4) Increase in mass and number of individuals is the characteristic feature of animal growth
4. Spirogyra r eproduces vegetatively by the method of
(1) spore formation (2) budding
(3) fragmentation (4) fission
5. Reproduction and growth are mutually inclusive events in ___________ organisms
(I) Bacteria
(I) Hydra
(III) Planaria
(IV) Diatoms
(V) Amoeba
(1) I, III and V only
(2) I, II and IV only
(3) I, IV and V only
(4) I, II and V only
6. Response to stimuli is seen in (1) eukaryotes only
(2) prokaryotes only
(3) all types of living organisms
(4) only those organisms that have well developed nervous system
7. Which character is seen exclusively in humans?
(1) Extrinsic growth
(2) Irritability
(3) Self consciousness
(4) Reproduction
8. Anabolism means
(1) synthetic reactions
(2) destructive reactions
(3) cellular organization
(4) consciousness
9. Which among the following is not a defining feature of living organisms?
(1) Reproduction
(2) Intrinsic growth
(3) Metabolism
(4) Consciousness
10. Read the following statements.
Statement I : The word systematics is derived from the Latin word Systema which means systematic arrangement of organisms
Statement II: Systematics takes into account evolutionary relationship between organisms
In light of the given statements, choose the correct answer from the options given below.
(1) Both statement I and statement II are correct.
(2) Both statement I and statement II are incorrect.
(3) Statement I is correct but statement II is incorrect.
(4) Statement I is incorrect but statement II is correct.
11. Select the correct order of the following taxa, order of Housefly, phylum of Man, family of Mango and class of Wheat
(1) Muscidae, Hominidae, Anacardiaceae and Poales
(2) Spermatophytes, Insecta, Primata and Poaceae
(3) Primata, Arthropoda, Poaceae and Dicotyledonae
(4) Diptera, Chordata, Anacardiaceae and Monocotyledonae
12. Read the following statem ents.
Statement I : The taxonomic categories are merely morphological aggregates, not distinct biological entities
Statement II: The basic requirement to place organisms in various categories is the knowledge of characters of an individual or group of organisms.
In light of the given statements, choose the correct answer from the options given below.
(1) Both statement I and statement II are correct.
(2) Both statement I and statement II are incorrect.
(3) Statement I is correct but statement II is incorrect.
(4) Statement I is incorrect but statement II is correct.
13. Read the following statements.
Statement I : The total number of plant and animal species described so far is slightly more than 1.5 million,
Statement II: But there is no clear idea of how many species are yet to be discovered and described due to our inability to explore all the areas where living organisms have colonized.
In light of the given statements, choose the correct answer from the options given below.
(1) Both statement I and statement II are correct.
(2) Both statement I and statement II are incorrect.
(3) Statement I is correct but statement II is incorrect.
(4) Statement I is incorrect but statement II is correct.
14 Given below are two statements: One is labelled Assertion(A) and other is labelled Reason(R).
Assertion (A) : Nomenclature or naming is only possible when organism is described correctly.
Reason (R) : Biologists do not follow universally accepted principles to provide scientific names to known organisms
In light of the above statements, choose the correct answer from the options given below.
(1) Both (A) and (R) are true and (R) is the correct explanation of (A)
(2) Both (A) and (R) are true but (R) is not the correct explanation of (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false
15. Which one of the following organisms is scientifically named and printed correctly, according to the International Rules of Nomenclature and correctly described?
(1) Musca domestica - The common house lizard, a reptile
(2) Plasmodium falciparum - A protozoan pathogen causing the most serious type of malaria
(3) Felis tigris - The Indian tiger, well protected in Gir forests
(4) E.coli - Full name Entamoeba coli, a commonly occurring bacterium in human intestine
16. Read the following statements.
Statement I: Scientific names for plants have been standardised through ICBN.
Statement II: Naming system which used three word format was given by Linnaeus.
In light of the given statements, choose the correct answer from the options given below.
(1) Both statement I and statement II are correct.
(2) Both statement I and statement II are incorrect.
(3) Statement I is correct but statement II is incorrect.
(4) Statement I is incorrect but statement II is correct.
17. Each biological name has two components
(1) generic name and variety name.
(2) generic name and specific epithet.
(3) generic name and subspecies name.
(4) species name and subspecies name.
18. Linnaeus evolved a system of nomenclature called
(1) trinomial nomenclature
(2) vernacular nomenclature
(3) binomial nomenclature
(4) polynomial nomenclature
19. Which of these rules should be fo llowed while writing scientific name of an organism?
(a) Biological names are generally in Latin and written in italics.
(b) The specific epithet and genus in a biological name, when handwritten, are separately underlined.
(c) First letter of specific epithet should be in uppercase
(d) First letter of genus should be in uppercase
(1) a, b and d only
(2) a, b and c only
(3) b, c and d only
(4) a, c and d only
20. Scientific name Mangifera indica Linn gives the following information.
(a) Genus name is Mangifera
(b) Specific name is indica
(c) It is first described by Linnaeus
(1) a only
(2) b only
(3) c only
(4) a, b and c
21. Read the following statements.
Statement I: Taxonomy is the process of classification.
Statement II: Classification is the process by which anything is grouped into convenient categories based on some easily observable characters
In light of the given statements, choose the correct answer from the options given below.
(1) Both statement I and statement II are correct.
(2) Both statement I and statement II are incorrect.
(3) Statement I is correct but statement II is incorrect.
(4) Statement I is incorrect but statement II is correct.
22. Consider the following statements:
i) Genus comprises a group of related species
ii) Taxon represents a taxonomic group of any ranking
iii) Family comprises a group of related genera
iv) Taxonomic category ‘class’ includes related phyla
Of the above statements:
(1) only i, ii and iv are correct
(2) only ii and iv are correct
(3) only i, ii and iii are correct
(4) only i and iv are correct
23. The taxonomic unit ‘phylum’ in the classification of animals is equivalent to which hierarchial level classification of plants?
(1) Class (2) Order
(3) Division (4) Family
24. Select the correct statements (i-iv) regarding taxonomic categories.
(i) Each step or rank in hierarchy is called taxonomic category.
(ii) Species is a group of individual organisms with fundamental similarities capable of breeding among themselves.
(iii) Taxonomic studies of all unknown organisms have led to the development of common categories like kingdom, phylum or division, class, order, family, genus and species.
(iv) Lower the category, greater is the difficulty of determining the relationship to other taxa at the same level.
(1) (i) and (ii) only
(2) (ii) and (iv) only
(3) (i) and (iii) only
(4) (ii) and (iii) only
25. Modern taxonomy is based on (A) external and internal features
(B) cell structure
(C) developmental process and ecological information of organisms.
Select the correct option.
(1) (A) and (C) only (2) (B) and (C) only (3) (A) and (B) only (4) (A), (B) and (C)
26. Match the column A with their appropriate taxonomic category in column B and choose the correct option.
Column A
Column B
(A) Diptera (I) Phylum
(B) Chordata (II) Order
(C) Anacardiaceae (III) Class
(D) Monocotyledonae (IV) Family
(A) (B) (C) (D)
(1) I II III IV
(2) I III II IV
(3) I IV III II
(4) II I IV III
27. Read the statements (A-C) given below and select the correct ones w.r.t. taxonomic categories:
(A) Species is the lowest rank in taxonomic category.
(B) Genera are aggregates of closely related species.
(C) indica, tuberosum and leo are specific epithets.
(1) (A) and (B) only (2) (A) and (C) only (3) (A), (B) and (C) (4) (A) only
28. Descending arrangement of various categories of classification is called (1) classification (2) systematics (3) hierarchy (4) key
29. Given below are two statements: One is labelled Assertion(A) and other is labelled Reason(R).
Assertion (A) : Each rank or taxon represents a unit of classification.
Reason (R) : Taxonomic categories are distinct biological entities and not merely morphological aggregates.
In the light of above statements, choose the correct answer from the options given below.
(1) Both (A) and (R) are true and (R) is the correct explanation of (A)
(2) Both (A) and (R) are true but (R) is not the correct explanation of (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false
30. Two different organisms belong to the same order but not the same genus. These two organisms may belong to the same
(1) family (2) species
(3) subspecies (4) order
31. Given below are two statements: One is labelled Assertion(A) and other is labelled Reason(R).
Assertion (A) : Living org anisms share similarities both horizontally and vertically
Reason (R) : Present day organisms are related to each other a nd also to organisms that ever lived on this earth
In the light of above statements, choose the correct answer from the options given below.
(1) Both (A) and (R) are true and (R) is the correct explanation of (A)
(2) Both (A) and (R) are true but (R) is not the correct explanation of (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false
32. Animals, mammals and dogs represent taxa at
(1) kingdom level
(2) phylum level
(3) class level
(4) different levels
33. Classification of plants proposed by Carolus Linnaeus was artificial because it was based on
(1) only a few morphological characters.
(2) evolutionary tendencies which are diverse.
(3) anatomical characters which are adaptive in nature.
(4) physiological traits along with morphological characters.
34. Read the following statements carefully with respect to features of living organisms and state them true(T) or false(F)
(1) Growth is seen only upto a certain age in animals
(2) Reproduction is not seen in all living organisms
(3) Metabolism can be regarded as defining feature of all living organisms
(4) All living beings have self–consciousness
(A) (B) (C) (D)
(1) T T T F
(2) F T T F
(3) T F T T
(4) F F T T
35. Which among the following taxa related to wheat, is to be written in italics?
(1) Triticum
(2) Poaceae
(3) Poales
(4) Monocotyledonea
36. Select the correct taxonomic categories of man, housefly and tiger that are equivalent to Anacardiaceae of mango.
Man Housefly Tiger
(1) Hominidae Muscidae Felidae
(2) Hominidae Muscidae Canidae
(3) Primata Diptera Carnivora
(4) Mammalia Insecta Chordata
37. Taxa like Sweet potato and mango are placed in taxonomic hierarchy in the
(1) different orders but same class and phylum
(2) different orders but same class and division
(3) same class and order but different family
(4) different class but same division
38. Two different plants are assigned to same species, if they
(1) have more than 90% similar genes
(2) look similar and possess identical secondary metabolites
(3) have similar number of chromosomes
(4) can sexually reproduce freely with each other and form fertile offspring.
ANSWER KEY
Drill
Exploration
and Reason
(Previous NEET Questions)
Chapter Test