Gr 10-Life Sciences-Study Guide

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LIFE SCIENCES STUDY GUIDE Grade 10

A member of the FUTURELEARN group

Life Sciences Study guide

1810-E-LIS-SG01

Í2*È-E-LIS-SG01[Î

Grade 10

CAPS aligned

ALL RIGHTS RESERVED ŠCOPYRIGHT BY THE AUTHORS The whole or any part of this publication may not be reproduced or transmitted in any form or by any means without permission in writing from the publisher. This includes electronic or mechanical, including photocopying, recording, or any information storage and retrieval system.

Every effort has been made to obtain copyright of all printed aspects of this publication.

However, if material requiring copyright has unwittingly been used, the copyrighter is requested to bring the matter to the attention of the publisher so that the due acknowledgement can be made by the author.

Life Sciences Textbook & Workbook Grade 10 NCAPS ISBN - 13:

978-1-86921-379-4

Product Code:

LFS 25

Authors:

Lorraine Kuun Susara Nortje

First Edition:

June 2011

PUBLISHERS ALLCOPY PUBLISHERS P.O. Box 963 Sanlamhof, 7532

Tel: (021) 945-4111, Fax: (021) 945-4118 Email: info@allcopypublishers.co.za Website: www.allcopypublishers.co.za

i

INFORMATION SHEET LIFE SCIENCES TEXTBOOK WORKBOOK GRADE 10 (NCAPS) The AUTHORS LORRAINE KUUN MSc., H.E.D.; 28 years of teaching experience: Life Sciences, Natural Science, Gr. 8 - 12, deputy chief marker NSC; co-ordinator for OBE, GET and FET at school; member of school’s management team; HOD; WCED revision and tutor programme 2009-2013; Telematics presenter; RSG radio revision; Bush Radio; Teaching Biology Project small group leader and presenter; educator training in EMDC; co-author of Life Sciences Textbook & Workbook Gr. 10. Natural Sciences OBE portfolio and workbook for assessment grades 8 and 9 SUSARA NORTJE B.Sc., H.E.D.; 27 years of teaching experience: Life Sciences, Natural Sciences Gr. 8 - 12; external marker: grade 12 Biology and Life Sciences; member of school’s management team; Head: Education and Training of Colors Academy since 2008; CEO of AmazingBrainz since 2012 co-author of Life Sciences Textbook & Workbook Gr. 10.; Natural Sciences OBE portfolio and workbook for assessment grades 8 and 9

To THE EDUCATORS 1.

2.

3.

4.

Answers to all requirements as set out in CAPS document.

Develops skills, knowledge and attitudes necessary for FET band, as well as tertiary education.

All specific aims are addressed, with appropriate assessment activities.

The text is learner friendly, while also scientifically correct with full explanations of difficult concepts, processes and structures.

5. Learning activities promote learning and can also be used for revision.

6. A wide variety of assessment activities included.

7. Learners and educators can choose activities suitable to individual circumstances.

8. Rubrics and memoranda in answer guide aid assessment; learners ensured of transparent and accountable assessment.

9. Provides tools for:  interactive learning  working according to scientific method  assessing prior knowledge  explaining everyday phenomena, structures and processes in a new, easy and scientifically correct language.  keeping up with current research and development 10. Educators are empowered to tackle new curriculum with confidence.

11. Workload of educators is so much lighter: no work sheets and rubrics have to be designed, no projects or practical investigations thought out – it’s all here!

12. Learners get a chance to improve their marks, and those interested in pursuing a career in Life Sciences or related fields can gauge their progress and chances of success. Learners are challenged to always try the next step.

ENDORSEMENT An excellent book that will inspire and stimulate learners in Life Sciences. The contents is presented to make learning fun and easy. I strongly recommend this professional publication for educators as well as learners.

Dr Alison Bennie – Botanist, University lecturer, Educator- Rhenish Girls’ High School The CAPS contents are covered comprehensively. The book also contains background information for those learners interested in a career in Life Sciences. Illustrations are of an excellent quality. The activities have clear criteria to make assessment easy and transparent for both educators and learners.

Johan Cilliers and Theunis van der Schyf, Life Sciences Educators – Huguenot High School, senior markers grade 12.

True to the CAPS; diagrams are scientifically correct and easy to interpret. Case studies and learning activities are interesting and promote critical thinking.

Carlyn Oppelt, 26 years experience as Life Sciences teacher, HOD at New Orleans Secondary Schools, deputy chief marker Life Sciences grade 12, RSG - revision, Telematics presenter ii

LIFE SCIENCES TEXTBOOK WORKBOOK GRADE 10 (NCAPS)

CONTENTS

1.

The study of life

1-6

Biochemistry – The molecules of life

7 - 29

2a. The cell – The basic unit of life

30 - 47

2b. Cell division – Mitosis

48 - 59

3.

Plant tissues

60 - 72

4.

Mammalian tissues

73 - 95

5.

Leaves – Plant organs for photosynthesis

96 - 101

6a. Anatomy of dicotyledonous plants

102 - 113

6b. Support in plants

114

6c. Transpiration

115 - 123

6d. Transport in plants

124 - 130

7.

Support systems in animals – The human skeleton

131 - 146

8.

Transport systems in the human body

147 - 167

9.

Biosphere to ecosystems

168 - 192

10. Biodiversity and Classification

193 - 204

11. History of life on Earth

205 - 237

iii

Life at the molecular, cellular and tissue level: Molecules of life

CHAPTER 1:

BIOCHEMISTRY—THE MOLECULES OF LIFE

Biology is an exciting and dynamic science that touches every aspect of our lives, from our health and behaviour patterns, to the challenging issues that confront us.



Research done in recent years has given us a renewed sense of the unity, but also a sense of the diversity of processes and adaptations. We can now have a renewed appreciation for our interdependence on all the other organisms with which we share this planet.

BIOLOGICAL ORGANISATION

Biology is the science of life – hence the name Life Sciences given to the subject.

Whether we study a single organism or a whole population, we will see a definite hierarchy of biological organisation. We can study each of the levels in this biological hierarchy by studying its components.

CHARACTERISTICS OF LIFE 

Organisms consist of cells – organisms can be unicellular or multicellular, but all of them consist of cells. (The cell theory that further explains this concept is discussed in the next chapter.)



Organisms grow and develop – cells grow in size or number, or both. Growth can differ from place to place. Development involves all the changes that occur from the origin of the species to the end of its natural life; changes and processes that are responsible for some of the most unbelievable adaptations to function.



Organisms regulate their own metabolic processes – chemical reactions and energy transfer processes take place in all living organisms. All of these processes and reactions together are known as the metabolism of the organism. Metabolic reactions take place in such a way that homeostasis occurs. Think of processes such as cellular respiration, protein synthesis, excretion etc., as well as the corresponding chemical reactions.



Organisms react to stimuli – all organisms react to stimuli from their internal or external environment. These stimuli can be anything e.g. colour changes, changes in light intensity, temperature, pressure, water potential etc.

Organisms often react by moving – away or towards the origin of the stimulus. Structures needed for these reactions had to develop.



Organisms reproduce – we already know that organisms develop from existing organisms. The multiplying of individuals (reproduction) can be sexual or asexual.

Organisms and populations adapt to their environments – adaptation (even over millions of years) is one of the most important mechanisms that enable organisms and populations to survive in a changing environment.

This process is known as “evolution”.

Each level of biological organisation has its own characteristics; a population will have certain features that will not be found in its individuals. The following are the levels of biological organisation:

Biological organisation – from atoms to organism, population to biosphere.

7

Life at the molecular, cellular and tissue level: Molecules of life 

Atoms form the most basic level of organisation. The smallest particle of an element is an atom.



Atoms combine to form molecules. Some are macromolecules; giant molecules such as the protein molecule.



Molecules and atoms together form the structures that cells consist of, the organelles.



Organelles form a living unit that can perform all the functions of life, the cell.



When a group of cells have the same structure and functions, we call it a tissue (plant and mammalian tissues are discussed later).



Tissues work together to form functional structures known as organs.



Organs join in systems with common function or functions, namely an organ system remember this definition when we learn about the transport and support systems in plants and animals).

3. are usually large and complex molecules, and 4. are combustible in oxygen to form, amongst other things, carbon dioxide.

Inorganic compounds 1.

2. do not contain carbon (with the exception of CO2, CO – carbon monoxide and -CN – cyanide compounds), 3. are elements and simple molecules, and 4. usually do not burn in oxygen.

INORGANIC COMPOUNDS AND ESSENTIAL ELEMENTS Water – H2O - is the most important inorganic compound that touches our daily lives.

An organism consists of a number of organ systems that work together to maintain homeostasis.



WATER The biggest part of most living organisms consists of water. About 20% of bone tissue in the human body consists of water, and about 85% of cells in the brain; on average our bodies consist of 70% water.

Various levels of ecological organisation can be described e.g. population, community and ecosystem.

(We deal extensively with these concepts in Environmental Studies.)

Water is not only an important component of our bodies; it is also, through photosynthesis, the source of the oxygen we inhale. The hydrogen atoms in water form part of the organic compounds in living organisms. Water is the solvent and medium in which most biological reactions take place. In many cases water is a reagent in these reactions.

BIOCHEMISTRY – THE ATOMS AND MOLECULES OF LIFE You already know that we need certain minerals and vitamins in our diets, and that organic compounds in our bodies have certain important functions. What do we mean when we use the terms “organic and inorganic compounds”?

Water is also one of the most important environmental factors that influence organisms.

Water is a habitat for many organisms. It is one of the most important factors in life and survival on planet earth. (We will discuss water and its importance in the sections on Support and Transport in plants, Transpiration as well as Environmental Studies.)

Organic compounds 1.

do not have a living origin,

generally have their origin in living organisms,

2. contain large numbers of carbon atoms, usually together with hydrogen, oxygen, nitrogen, and/or phosphorus (H, O, N and P),

8

Life at the molecular, cellular and tissue level: Molecules of life Gastric juice and the hydrochloric acid in the stomach are acidic, the small intestine, however, is alkaline.

The cells of the body are neutral; with the exception of the digestive enzymes, most enzymes prefer a neutral medium of 7,2 to 7,4 in which to function.

Water has polar molecules; one side slightly negatively charged, while the other side is slightly positively charged.

H

H O

The pH of blood is maintained between very narrow margins at an average of 7,4. Should the blood become too acidic (e.g. during suffocation) a coma and even death can follow. Alkaline blood can lead to nerve problems and even to convulsions.

+ H

+ O

O

H

H

+ O

H H O

+

Organisms have many natural buffers. A buffer is a substance or combination of substances that counteract pH changes, even though an acid or alkaline is added. (More about this when we talk about gaseous exchange in grade 11.)

H

H

H

When an acid reacts with a base, a salt is formed e.g.: HCl + NaOH ď‚Ž NaCl + H2O Hydrogen bonds between water molecules.

When salts dissolve in water, the ions dissociate (e.g. Na+ and Cl-) to form electrolytes. Electrolytes can conduct electric currents and play a very important role in conducting nerve impulses, as well as in muscle functioning. Several homeostatic processes strive to maintain the electrolyte concentrations in the body. e.g. excretion.

The molecules of water form hydrogen bonds with one another; these relatively strong intermolecular forces are responsible for the cohesion forces between water molecules. The polar nature of the water molecules is also the reason why they can form strong adhesion forces with many other substances. Cohesion and adhesion forces are responsible for capillarity, where water rises against gravity in narrow, capillary tubes (remember these facts when we talk about Transport of water in plants).

pH scale Battery acid 0.0 Hydrochloric acid 0.8 Stomach acid 1.0

Substances that react readily with water, or that are water-soluble are hydrophilic (e.g. sucrose and table salt), while substances that do not dissolve in water (e.g. fats and oils) are hydrophobic.

Stomach gastric juice 2.0 Increasing acidity

Vinegar 3.0

Beer 4.5 Black coffee 5.0

MINERALS Certain elements are absolutely essential in the normal functioning of cells, metabolic processes and the general well-being of the body (see table at end of chapter).

Neutrality

Minerals that we need in large quantities every day are macronutrients, e.g. C, H, O, N, P, S, Ca and Mg.

Rainwater 6.25 Cow milk 6.5 Distilled water 7.0 Blood 7.4 Seawater 8.0 Bleach 9.0

Micronutrients are equally important, but we only need small quantities every day, e.g. Fe, Na and I2.

Increasing alklinity

ACIDS, BASES AND SALTS The pH scale is an instrument to indicate the degree of acidity or alkalinity. A pH of 0 to 6 indicates an excess of H+ ions (acid), 7 is a neutral pH and 7 to 14 indicates an excess of OH- (alkaline/basic).

Household 11.5

Oven cleaner 13.0 Lye 14.0 The pH of a few well-known substances and body fluids

9

Life at the molecular, cellular and tissue level: Molecules of life Two well-known pentose sugars that are important to us, are ribose and deoxyribose, respectively part of RNA and DNA (more about this in our section on nucleic acids and in grade 12 when you will learn about DNA and RNA in detail).

ORGANIC COMPOUNDS There are many different organic compounds; more than 5 million different types have been identified by researchers.

The name “organic” compounds come from the days when it was thought that these compounds could only be formed in living organisms. In 1982 the German scientists, Friedrich Wühler, produced urea in a laboratory, and today we know that many organic compounds will never be found in living organisms.

The three hexose sugars that are important to us are glucose, fructose and galactose.

The diversity of organic compounds can be attributed to the fact that they can form a number of three-dimensional compounds. The carbon atom, central in organic compounds, can bind with a large number of other elements. Organic compounds are also generally macromolecules, the giants in the molecular world.

Glucose can also be used to form other organic compounds such as amino acids and fatty acids. The concentration of glucose in the blood is under homeostatic control. The hormone insulin, among others, is responsible for this.

Glucose is the most common hexose sugar and is the source of energy for most living organisms. The hexose sugars generally occur as ring structures.

Fructose is found in fruit and honey and, interestingly enough, it is sweeter than glucose.

The most common organic compounds are fats (lipids), carbohydrates and proteins. Organic molecules are usually polymers consisting of smaller building blocks, the monomers.

Galactose is part of the disaccharide lactose, or milk sugar.

CH2 OH

CARBOHYDRATES

(or)

O

C 2 OH (of) CH

O

Sugar, starch and cellulose are all examples of carbohydrates. Sugar and starch are the sources of energy for cells, and cellulose is an important structural component of the cell walls of plant cells.

HO

Carbohydrates contain carbon, hydrogen and oxygen in the ratio of 1:2:1. (The “hydrate” part refers to the hydrogen-oxygen ratio of 2:1, the same as that for water.)

The ring structure of glucose (not for exam purposes).

OH

OH

HO

OH

OH

OH

OH

DISACCHARIDES

The building blocks of carbohydrates are simple sugars (monosaccharides). Disaccharides consist of two monosaccharides, while polysaccharides consist of a large number of monosaccharides.

Disaccharides consist of two monosaccharides bound together. We have three different disaccharides, and in all three cases glucose is one of the two sugars. glucose + glucose  maltose (malt sugar)

MONOSACCHARIDES

glucose + fructose  sucrose (cane sugar)

Monosaccharides can have three to seven carbon atoms. The better-known ones are the triose sugars (3-C e.g. glyceraldehyde), the pentose sugars (5C) and the hexose sugars (6C).

glucose + galactose  lactose (milk sugar) Monosaccharides and disaccharides are soluble in water.

10

Life at the molecular, cellular and tissue level: Molecules of life POLYSACCHARIDES

FATS AND OILS (LIPIDS)

A polysaccharide is a macromolecule that consists of thousands of interconnected monomers, usually glucose. The most common polysaccharides are starch, glycogen and cellulose.

Fats (lipids) are soluble in non-polar solvents (e.g. ether) and insoluble in water (hydrophobic).

These characteristics result from their structure: long chains of carbon and hydrogen with a few functional groups that contain oxygen.

The building blocks of fats are glycerol and fatty acids.

Glycerol is a type of alcohol with three hydroxyl groups, and fatty acids have long hydrocarbon chains.

Fats are stored under the skin as insulation against cold, and is an excellent form of reserve energy.

Polyunsaturated fats tend to be more oil-like at room temperature and saturated fats are generally harder. This characteristic is the reason why fats are not healthy and can lead to cardiovascular disease. Hard fats clog arteries and can cause thrombosis.

It is, however, necessary to include fats in our diet (omega-3 fatty acids) for normal metabolic reactions, and because some vitamins (A, D, E and K) are only soluble in fats. Phospholipids (fats bound to phosphates) form part of cell membranes.

Cholesterol is essential for the forming of cell membranes, but too much in the blood can lead to plaques in the blood vessels.

Starch consists of networks of glucose chains.

Starch is the usual form in which carbohydrates are stored in plants. One type of starch, amylase, has shorter, unbranched chains, and amylopectin has long, branched chains consisting of about 1000 glucose molecules. Amylopectin is the most common form of starch, and like other polymers it is not soluble in water. Amylose is soluble to a certain degree.

Steroids are formed from fats; biologically important steroids, for example, are cholesterol, bile salts, reproductive hormones and cortisol secreted by the adrenal glands.

Glycogen is sometimes also known as “animal starch� as it is the form in which reserve carbohydrates are stored in animal cells. It is soluble in water, and stored in muscle and liver cells.

Did you know?

Cellulose is the structural polysaccharide in plants.

About 50% of wood consists of cellulose, and about 90% of cotton! Cellulose is the part of cell walls that gives strength and support to plant cells.

Fats are broken up into tiny droplets (emulsified) by fast whisking, or by adding soap (alkaline) or lemon juice (acidic). These are the three things you do when you help to do the fatty dishes! (Fats in your stomach are emulsified by the acid in gastric juice.)

Cellulose has complex molecules and is insoluble in water.

It is important in our diets as roughage to stimulate peristalsis.

We cannot digest cellulose, but some micro-organisms can. Herbivores that mainly eat grass have bacteria in their digestive tracts that can digest cellulose. This is how they get nutrition from grass.

Chitin is a substance found in the exoskeleton of insects as well as the cell walls of fungi. Its structure is related to that of cellulose.

11

Life at the molecular, cellular and tissue level: Molecules of life

H C

CH3

H

X The structure of a fat (not for examination purposes). Note the unsaturated bond at X. Polyunsaturated fatty acids contain large amounts of these bonds.

PROTEINS

AMINO ACIDS

Proteins, with amino acids as monomers, are the most versatile of all the organic compounds.

There are 20 different amino acids that act as building blocks for proteins.

Proteins are involved in all cellular reactions; all enzymes are proteins. In cell membranes they play an important structural role. Because they occur in a variety of shapes and sizes, they are especially important in the structure, growth, maintenance and repair of cells.

Amino acids bind by means of peptide bonds. Two amino acids form a dipeptide, three a tripeptide, and more a polypeptide. Fifty or more amino acids are a protein.

A

H O

Proteins play a role in transport (haemoglobin in blood, carrier molecules in cell membranes), as nutrients (albumin in eggs, meat protein), some hormones (insulin), movement (action in muscle cells), and protection against disease (antibodies).

H

B

Proteins can also serve as a reserve source of energy. Excess amino acids are broken down in the liver to be converted into energy-rich fats or glucose.

H

Proteins are so versatile because they have a very complex structure.

N H

N

C

H

CH3

H

O

C

C

H

C OH

CH3 N

C

H

H

O C OH

The basic structure of an amino acid (A) and a dipeptide (B) – (not for exam purposes).

12

Life at the molecular, cellular and tissue level: Molecules of life Bacteria and plants can produce their own amino acids from more simple compounds. Animal cells can also produce some of the simple amino acids.

The essential amino acids are those that cannot be produced by animal cells, or not in sufficient quantities.

These amino acids are obtained from plants; remember to eat your daily helping of fruit and vegetables!

The sequence in which amino acids occur, is its primary structure. The number of amino acids, which of the twenty possible amino acids occur, how many of each and in which sequence, are all factors that make it possible to have such a vast array of different proteins. +H N 3

His Ser Gln Gly Thr Phe Thr 1

2

3

4

5

6

COO

The quarternary structure of proteins determine the actual structure and functioning of proteins. The picture on the left illustrates the structure of haemoglobin and on the right is a representation of collagen (not for exam purposes).

7

The primary structure of a protein is determined by the number and sequence of amino acids (detail not for exam purposes).

Heat or pH changes cause a protein to denature and the three-dimensional structure is destroyed. The protein cannot function properly anymore. Low temperatures will make proteins inactive.

The secondary and tertiary structures refer to the shape of the polypeptide (polypeptide – many amino acids, but not a protein yet).

Polymers are formed by condensation synthesis. This means that for every monomer added, a water molecule is released. Polymers are broken up by hydrolysis (adding water) into smaller units (monomers). These reactions are controlled by enzymes.

HO

OH+HO

OH

HO

O

OH+ H2O

B The processes of condensation synthesis (  ) and hydrolysis ( ). Both reactions are catalysed by enzymes.

A

The secondary structure (A) and tertiary structure (B) of proteins (you do not have to know the biochemical structure of proteins or amino acids; all the diagrams are given to aid you in understanding the concepts).

ENZYMES Enymes are biological catalysts – they start or accelerate biochemical reactions without taking part in the reactions or undergoing any changes themselves.

Proteins are produced in the ground plasm of the cell at the ribosomes. DNA controls the process via RNA (more about this in grade 12).

Actually all enzymes are proteins, and everything that is true for proteins, will also be true for enzymes.

Enzymes are pH and temperature specific. Heat will cause them to denature, while cold will make them inactive. The optimum temperature (where they work best) for enzymes in the human body is 37°C.

The three-dimensional structure of proteins (tertiary and quaternary) is important for the normal functioning of the molecule.

13

Life at the molecular, cellular and tissue level: Molecules of life

ENZYME ACTIVITY Enzyme activity

Enzymes work according to a lock-and-key mechanism. The enzyme molecule has an active centre that will only recognise a specific molecule or specific type of substrate (enzymes are substrate specific).

Active centre

Temperature in °C

Different enzymes prefer different temperatures; in the human body the optimum temperature is 37

+ +

Substrate Substraat

Enzyme activity

Enzyme Ensiem

Temporary enzyme - substrate complex

pH Enzymes are pH specific; some has optimum functioning at an alkaline medium, others prefer an acidic medium. Two digestive enzymes are represented in this graph. Enzyme A is found in the stomach and enzyme B in the small intestine. What can you deduce about the pH in these organs? +

INHIBITION OF ENZYMES Enzyme

Sometimes enzymes have to be temporarily inactivated. A certain substance will bind with the active centre until the enzyme is needed again. This is a way to control metabolic processes.

+

Product

The lock-and-key mechanism of enzyme functioning.

Enzymes can be used over and over again, and only small quantities are necessary to catalyse a large amount of substrate. Reactions can be anabolic (building up) or catabolic (breaking down).

Did you know?

Enzymes can be inactivated permanently; some toxins inhibit enzymes by connecting to the active centre or somewhere else. Heavy metals such as lead and mercury permanently bind with certain enzymes. Cyanide is a poisonous gas that inhibits one of the enzymes in the process of cellular respiration.

Enzymes lower the activation energy needed before a reaction can take place.

The way some medicines work is based on the principle of enzyme inhibition; bacterial enzymes are inhibited by the antibiotic penicillin.

14

Life at the molecular, cellular and tissue level: Molecules of life



CO-ENZYMES AND CO-FACTORS Some enzymes need non-protein parts in order to perform their functions. The protein part is the apo-enzyme, and the non-protein part the prosthetic group (co-factor).

Neither the apo-enzyme nor the prosthetic group can function individually, but together they have a metabolic function. The co-factor can be organic or inorganic.

This process is less toxic, cheaper and natural resources (water and electricity) are saved.

In some cases the co-factor is a metal ion e.g. iron, magnesium, calcium or zinc; many minerals act as co-factors.



An organic, non-protein part connected to the apo-enzyme, and acting as co-factor, is a co-enzyme.

One of the well-known co-enzymes you will hear about is co-enzyme A that plays a role in respiration.

Many vitamins are co-enzymes.

These enzymes have been extracted and enhanced by biotechnology. The quality of the products is better and the production costs are lower.

ENZYMES IN OUR DAILY LIVES Source: http://biotech.about.com

Enzymes are also used to break starch down into sugars. The food industry uses corn and wheat to produce sweet syrups. Using these syrups is much more cost effective than using cane sugar.

Enzymes are good examples of biotechnology that is used daily in our households. In many cases enzymes were extracted and used in their natural state. With research and biotechnology the enzymes have been modified to be more effective in for example, unfavourable pH or temperatures, conditions that were inhibitory to enzyme activity.

Removal of sticky glue Enzymes are used in the pulp and paper industry for removal of sticky glues from paper that has been recycled. This glue not only reduces the quality of the paper products, but can also clog the machinery.



Leather Enzymes are used to clean the animal hides by removing keratin and pigment stains.



Biodegradable plastic Plastic products contain long carbon hydrogen chains; difficult to break down by micro-organisms.

Biodegradable plastic is manufactured from plant polymers that are shorter and easier degradable by decomposers. These products are unfortunately still too expensive to use.

The use of chemicals to remove the glue has not been 100% successful. The glue is held together by ester bonds.



The enzyme, esterase is used to break the glue into smaller, water soluble compounds that can be removed much easier.



Food and beverages Humans have been using enzymes for centuries to produce foods, without really knowing it.

It was possible to make wine, beer, vinegar and cheeses, for example, because of the enzymes in the yeasts and bacteria that were utilised.

LEARNING ACTIVITY 1



Textiles There are increasing demands on the textile industry to decrease pollution. By means of biotechnology the harsh chemicals were replaced by enzymes. The latter are used to prepare cotton for the weaving process and to remove impurities.

Detergents Enzymes have been used in detergents for a very long time, especially those that degrade protein-causing stains, for example stains caused by grass, red wine and soil.

Bioethanol Bioethanol is already well-known to the general public. It is manufactured from plants with a high starch content by enzymes that are able to catalyse these conversions efficiently.

There are increasing concerns that this process might influence food production negatively.

Lipase is another enzyme that can be used to dissolve fatty stains. Recently, research has been done to produce enzymes that are effective in hot or cold temperatures.

15

Life at the molecular, cellular and tissue level: Molecules of life

Questions:

4.

Enzymes used in detergents must be effective in hot or cold water. Why is this necessary for the sales of the detergents?

1.

List the seven applications of enzymebiotechnology mentioned in the passage and supply a suitable example of each.

______________________________

______________________________

______________________________

______________________________

______________________________

5.

______________________________ ______________________________ ______________________________ ______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

______________________________

6.

______________________________

______________________________

______________________________

______________________________

Explain the meaning of the terms: (a) biodegradable

7.

Design an experiment in your work book to test the effect of different enzyme-containing washing powders on different types of stains.

Pay attention to the following in your design (refer to the part of the scientific method in the previous chapter, as well as the assessment activities at the end of this chapter for guidelines):

7.1

Asking a focus question

______________________________

7.2

Formulating a hypothesis

(c) polymers

7.3

Identifying the variables

______________________________

7.4

Method according to which experiment will be performed

______________________________

7.5

Apparatus needed

Do your own research and write an equation for the process during which ethanol is produced from glucose.

7.6

Any other aspect that needs to be taken into account in your planning.

______________________________

7.7

Recording of observations

______________________________

7.8

Any conclusions that can be made

______________________________

7.9

Accepting or rejecting hypothesis

______________________________ ______________________________ ______________________________ (b) catalyst

______________________________ ______________________________

______________________________

3.

What is the pH preferred by the enzymes in washing powders? How do you know that?

______________________________

______________________________

2.

Have a look at the washing powder used in your home. Read the contents label and determine if there are any enzymes in the detergent. Find out what the name of the enzyme is and the type of stain(s) it can remove.

7.10 Graphic representation of data collected 16

Life at the molecular, cellular and tissue level: Molecules of life

NOTES :

NUCLEIC ACIDS

______________________________

The nucleic acids transfer genetic information and determine the types of proteins produced by a cell.

The nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). (You will learn more about them in grade 12.)

______________________________ ______________________________ ______________________________

VITAMINS

______________________________ ______________________________

Vitamins are organic compounds essential for normal metabolic reactions (table at end of chapter).

______________________________ ______________________________

We need them in relatively small amounts.

Vitamins are divided into two groups: the fat soluble vitamins A, D, E and K, and the water soluble B and C vitamins.

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Researchers are still unsure about the effect of large doses of vitamins to prevent colds, for example. We do know that water soluble vitamins are excreted via urine, but the fat soluble vitamins collect in the body, cannot be excreted easily and can cause serious problems when concentrations in the body are too high.

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Did you know?

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Fat-soluble vitamins in excessive quantities cause hypervitaminosis. The liver of a steenbras (grunter) contains so much vitamin A that eating it will cause nausea, flaky skin and hair loss.

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Even the indiscriminate use of vitamin supplements can make you sick!

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LEARNING ACTIVITY 2 : MOLECULES FOR LIFE

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1.1

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Name the elements that fats and oils consist of.

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1.2

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Name the molecules (building blocks) that fats and oils consist of.

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1.3

What is the difference between a fat and an oil?

(Name any one.)

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1.4

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Name any three functions of fats in living organisms.

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