Nutrient Compounds

TEMPLATE FOR A UNIT OF TEACHER SUPPORT MATERIAL

1. SUBJECT: Biology

2. FORM: S. 3

3 UNIT: 3

4. TOPIC: Nutrition in plants and animals

5. SUB-TOPIC: Nutrient compounds.

6. INTRODUCTION:

Cells, tissues and organs are composed of chemicals. Chemical compounds are divided into two groups: - organic and inorganic, and both occur in living things.

The main organic compounds found in organisms are carbohydrates, fats, proteins, and nucleic acids. The main inorganic compounds are:-minerals salt and water.

These chemical substances must be obtained as nutrients in correct proportions if the organism is to function efficiently.

In humans, the nutrients form the constituents of a balanced diet. Lack of nutrients especially minerals and vitamins lead to deficiency diseases.

This unit reviews the structure, properties and functions of nutrient compounds, also known as chemicals of life namely: -

• Carbohydrates
• Proteins
• Lipids (fats and oils)
• Water
• Vitamins
• Minerals and
• Enzymes.

It also has several experiments to test for the nutrient compounds. These have been given in reasonable detail. The learner will have an opportunity to be able to follow instructions, make proper observations and relevant deductions.

7. BRIEF DESCRIPTION OF UNIT OF TEACHER SUPPORT MATERIAL:

This unit deals with:

• Macro and micronutrient compounds
• Enzymes, factors affecting their activity and their properties.
• Effects of nutrient compounds on health, growth and development.
• Food tests and procedures

8. NUMBER OF LESSONS (OR HOURS): 19 Periods.

9. SUMMARISE THE MAIN CONTENT AND CONCEPTS THAT THE TEACHER SHOULD EMPHASISE IN TEACHING THE SUB-TOPIC:

• Definition of nutrient compounds.

• Examples of nutrient compounds namely; carbohydrates, vitamins, proteins, fats and mineral salts and water.

• Examples of food substances that contain the nutrient compounds.

• Importance of nutrients with respect to growth, health and development.

• Food tests to establish presence of the nutrient compounds namely Starch test, Protein test, Reducing and Non - reducing sugar test, Benedicts and Vitamin and Lipids test.

• A balanced diet and its components.

10. LIST ITEMS OF TEACHING/LEARNING MATERIALS:
(Worksheet, stimulus activity, experiments, items of evidence, statistics, texts, pictures, diagrams, graphs)

Reagents: -

• Iodine solution, Benedict’s solution / Fehling’s solution, Ethanol, Dilute Hydrochloric acid, Dilute Sodium hydroxide, Copper II Sulphate solution, DCPIP, Pepsin, Amylase,

Foodstuffs: -

• Sources of catalase e.g. liver, Irish potato, seeds.
• Meat, fish, cabbages, oranges, pineapples. Vegetables like dodo milk. Fat, oil/castor oil, Distilled water

Apparatus and Materials

Test tubes, thermometers, Boiling tubes, Droppers, Saliva, Water Bath, Heat source, measuring cylinders, Stop clock, ice, labels/stickers.

Others: -

Textbooks, journals, and other alternative teaching and learning aids like straws, transparent mineral water bottles, plastic cups, e.t.c.

Charts of local food items that contain starch, fats and proteins.

WORKSHEET FOR EXPERIMENTAL ACTIVITY I: FOOOD TESTS.

Experiment I

Aim:

To test for reducing sugars

Test	Observation	Conclusion
Add 1 ml of glucose solution in a test tube, Add Benedicts/Fehling’s solution until the mixture turns blue. Boil the mixture for 1 minute.

Experiment II

Aim:

To test for starch

Test	Observation	Conclusion
Add 1 ml of 1% starch solution in a test tube. Add 3-5 drops of iodine solution and observe the colour changes on a white background.

Experiment III

Aim:

To test for non-reducing sugars

Test	Observation	Conclusion
- Add 1ml of sucrose solution in a test tube; add 1ml of Benedicts/Fehling’s solution until the mixture turns blue. Boil the mixture for 1 minute
- If the mixture remains blue, proceed by putting - 1 ml of sucrose solution in anther test tube - Add 3 drops of dilute hydrochloric acid and boil for 1minute. Cool in cold water - Add sodium hydrogen carbonate / Sodium hydroxide - Until fizzing stops. - Add Benedict’s solution to the mixture - Boil the mixture for 1 minute.

Experiment IV

Aim:

To test for proteins

a) Biuret Test

Test	Observation	Conclusion
- Add 2cm3 of egg white suspension/milk in a test tube add 1cm3 of dilute sodium hydroxide solution. - Add 1% copper sulphate solution to the mixture drop wise - Note the colour change especially where the two solutions meet.

b) Million’s Test

Test	Observation	Conclusion
1 Add 2cm3 of egg white suspension in a test tube add 2-3 drops of Million’s reagent. Shake well to mix - Boil for 2 minutes.

Experiment V.

Test for Lipids: (fats and oils)

The fat/oil test is either physical or chemical.

1. Grease spot test (physical test)

Test	Observation	Conclusion
Place a drop of fat or rub fat on a paper, Alongside the spot, place a drop of water Leave the paper to dry then hold the paper against light

ii) Emulsion Test (chemical test)

Test	Observation	Conclusion
- Add 2 drops of oil in a test tube; add an equal volume of ethanol. - Shake thoroughly, - Add an equal volume of water

WORKSHEET FOR EXPERIMENTAL ACTIVITY II:

EXPERIMENTS ON ENZYMES.

Experiment I

1. Aim:

To investigate the action of pepsin on the egg albumen.

Test	Observation	Conclusion
- Prepare a water bath and maintain it at 350-370 C, - Place 2cm3 of egg albumen suspension into four test tubes and label them A, B, C and D. - Add three drops of hydrochloric acid to each of tubes B, C and D. - Boil 1 cm3 of 1% pepsin in a test tube and add it to test tube D. - Add 1cm3 of 1% unboiled pepsin to test tubes A and C. - Place all 4 tubes in the water bath at 370 C. - Examine the tubes every 2 minutes and after 10 minutes remove and place them in a test tube rack.

Experiment II

2. Aim:

To investigate the effect of temperature on the action of salivary amylase enzyme.

Test	Observation	Conclusion
- Prepare a water bath and keep it at 350C-400C.Rinse your mouth with clean warm water and collect about 5cm3 of saliva in a test tube. - Place the test tube with saliva in the water bath. Label three test tubes 1, 2 and 3.Put 2cm3 of starch solution in each. Add 1cm3 of saliva to test tube 1, 2, and 3. - Place the three test tubes in beakers of water maintained at different temperatures of 050C, 350C, 500C. - Immediately remove a drop from each test tube and place it on the white tile. - -- Apply drops of iodine solution and record your observations. After 10 minutes, test a drop from each of the three test tubes with iodine, - Add 0.5 ml of Benedict’s solution to the remaining solution in the three test tubes and boil

Questions

1. Explain the colour changes in test tubes 1, 2, and 3
2. In which test tube(s) did the colour of iodine:

1. Persist ii) Turn blue –black?

3. Aim:

To investigate the presence of catalase living tissues.

Test	Observation	Conclusion
- Label 4 test tubes 1, 2 3 and 4. Add 2cm3 of hydrogen peroxide to each of the test tubes 1, 2 and 3. - Add 2cm3 of distilled water to the fourth test tube, - Peel the potato or pawpaw and cut it in small cubes. Drop one cube in each of the 4 test tubes. - Record your observations using as: No reaction, Slow reaction, Moderate reaction, Vigorous or very vigorous reaction - Test any gas given off using a glowing splint. Prepare one other test tube with hydrogen peroxide and treat it as follows:- - Drop one pieces of liver in a test tube and observe and record your observations.
- Prepare one other test tube with hydrogen peroxide and treat it as follows: - Place three soaked seeds in the test tube. - Record your observations using the format above.
- Prepare one other test tube with hydrogen peroxide and treat it as follows: -Drop keratin (nails) or hair in a test tube with hydrogen peroxide. - Record your observations using the format above.

Questions

1. Name the gas given off in the experiment above.

2. Name the enzyme found in plant and animal tissues.

11. TEACHER’S GUIDE:

Include essential teacher information on separate pages: topic notes, learning objectives, organisational advice and tips, answers to student exercises, advice on assessment/evaluation, marking and exam preparation, suggested follow-up and extension work, useful textbook references and other resources).

Prerequisite knowledge

Teachers should be guided by the 553 syllabus

For the teacher and students

• They should know the various local food stuffs that provide the nutrient compounds discussed in the texts/content
• The teacher should integrate theory with practical work so as to consolidate the content

Useful tips for the teacher

• Some reagents like Million’s reagent and Sudan III dye are toxic and should be handled with care.
• For practical lessons, the teacher should be conversant with the right procedure, correct reagents, right quantities, making correct observations and correct recording of results.
• For reducing sugars the teachers should know the range of colours that take place due to the different concentrations of reducing sugars.
• Teachers should know the reagents, their colour and resultant colour changes for the various nutrients.
• Avoid dual-colours e.g. blue-black, yellowish green e.t.c
• All colour changes for the food tests must start with the colour of the reagent and then go through all those observed.
• It is advisable to use small quantities of the test reagents for better results.
• It is advisable that practical work be done in groups of preferably 5 – 6 students.
• Students should carry out a negative test so as to make justifiable conclusions.

Organizational advise:

Let the students be given projects and discussion work on the subject like investigating the effect of mineral salts required by plants.

Teachers and students should use any resource center in their locality; attend workshops, seminars on nutrition.

REFERENCES:

1. John Kaddu, Mary Jones and Geoff Jones (1999). Biology for East Africa Cambridge University Press

2. Beckett, B.S. (1982). Biology; A Modern Approach (2^nd ED) London. Oxford University Press

3. Mackean D.G (1973). Introduction to Biology London (UK) Hodder Murry

4. Maxwell Ojo.B. (1998) Modern Tropical Biology. London Evans and Brothers (UK)

5. Stone R.H and Cozens A.B (2002) New Tropical Biology (3^rd ED). London (UK) Longman

6. Norah Tushabe: Bertha Mubiru and Samuel Olong. Biology Senior Two; published by MK publishers.

7. Rose Rwakasisi: Biology, UCE Revision by Fountain publishers

8. E.A Oketta and Bertha Mubiru: Biology A Complete Course; By Fountain publishers.

9. C.B. Nyavor and S. Seddoh: Biology for Senior Secondary Schools; By Macmillan publishers.

10. K.I.E (Kenya Institute of Education): Secondary Biology and Biological Sciences.

11. C.J. Jegede. Biology: Page 86

12. S.O Iloeje: Certificate Practical Biology. Published by Longman.

13. Soper and Smith: Integrated Biology for East Africa

By means of arrows connect column A (The deficiency disease) to column B (The essential nutrient lacking in the diet)

	Column A	Column B
1	Marasmus	Lack of vitamin A
2	Kwashiorkor	Lack of iron
3	Rickets	Lack of vitamin C (Ascorbic acid)
4	Simple goitre	Lack of all food nutrients
5	Scurvy	Lack of proteins
6	Anemia	Lack of iodine
7	Night blindness	Lack of calcium and phosphorus or Vitamin D (calciferol)
8	Beri beri	Lack of vitamin B2 (Nicotinic acid)
9	pellagra	Lack of vitamin B1 (Thiamine)

ACTIVITY 1, 2 AND 3

Aim: testing for lipids (fats and oils)

Requirements: (Each group to have the following)

• 6 test tubes in test-tube racks
• Cooking oil
• Fat e.g. Butter or margarine
• Groundnuts / Simsim / sunflower paste
• Ethanol
• 6 pieces of brown paper or filter paper
• Distilled water
• 5-10ml measuring cylinder
• Sudan III dye solution
• Clock /watch

Activity 1 (emulsion test)

Procedure:

1. Pour 2cm³ of ethanol into a test tube.

2. Add one drop of cooking oil or a small piece of fat to the ethanol in the test tube.

3. Cover the open end of the test tube with your thumb and shake the test tube thoroughly to mix the contents.

4. Pour the mixture into the second test tube containing about 2cm³ of water.

5. Note the appearance of the mixture on shaking ethanol with oil, and after adding this mixture to water.

Questions:

1. What happened to the cooking oil:-

1. As soon as it was added to the ethanol?
2. After shaking with the ethanol?

2. What was the appearance of the mixture on adding the

Contents (mixture) to water?

Activity .2 (Grease spot test)

Procedure:

1. Place a drop of cooking oil on a brown paper provided or on the white sheet of filter paper.

2. Leave for a few minutes and then hold the paper against light.

3. Record your observations

4. Repeat steps1 and 2 using water instead of cooking oil on another piece of paper.

6. Repeat the above procedure, but using groundnuts, simsim or sunflower paste.

Questions:

1. What difference do you note between the drop of cooking oil and drop of water when added to the pieces of paper?

2. Did the mark /grease formed by the cooking oil allow you to see through?

3. What is such a mark called?

Activity. 3 (Sudan III dye test)

Procedure:

1. Put 2-3 drops of cooking oil into a test tube.

2. Add a few drops of Sudan III dye

3. Add water and shake vigorously

4. Leave the contents to settle for about 5 minutes.

5. Record your observations

Questions:

1. Which layer contained the Sudan III dye colouration?

2. What does this indicate?

13. ADDITIONAL MATERIALS:

Use extra pages to give the exact text of student worksheets, questionnaires, tests, and subject content/definitions or program idea.

Glossary:

Enzyme – These are biological catalysts made by living organisms that speed up chemical reactions

Starvation is a condition where one stays for long periods without eating food

Malnutrition – is a condition caused by eating an unbalanced diet especially when the diet lacks more than one or more types of food.

Balanced diet – is one containing all food values in their right proportions

Absorption – Is the up take of a substance the cells of an organism’s body.

Amino acid – Building blocks of proteins.

Polysaccharide: A carbohydrate such as starch or cellulose whose molecules are made of many units of sugar joined together.

Saliva – artery fluid containing salivary amylase and mucus secreted from into the mouth by salivary glands.

Roughage – Fibrous indigestible food that stimulates the walls of the alimentary canal. It is sometimes referred to as fiber.

Heterotrophic nutrition – Is type of nutrition where organisms obtain food from complex substances that they breakdown into simple absorbable substances.

CARBOHYDRATES

They are organic compounds made up of the elements: Carbon, Hydrogen and Oxygen.

The general formula for a carbohydrate is:

(CH₂0)n where ‘n’ represents the number of carbon a torus a molecule of carbohydrate has.

The simplest carbohydrates are the sugars (saccharides), including glucose and sucrose.

Polysaccharides are carbohydrates of much greater molecular weight and complexity; examples are starch, glycogen, cellulose, lignin and chitin.

Carbohydrates can be divided into three groups depending on the size of their molecules, these are:

• Monosaccharides (simple sugars)
• Disaccharides (Non –reducing sugars)
• Polysaccharides (the starches)

Carbohydrates perform many vital roles in living organisms:

Sugars e.g. glucose are essential intermediates in the conversion of food to energy.

• Starch and other polysaccharides serve as energy stores in plants, particularly in seeds, tubers, etc
• Cellulose, lignin, form the supporting cell walls and woody tissue of plants.
• Chitin is a carbohydrate, but containing nitrogen. chitin is a structural

Polysaccharide found in body walls of many invertebrate animals.

• Carbohydrates also make bacterial cell walls.

MONOSACCHARIDE (simple sugars)

This is a carbohydrate that cannot be splint into smaller units by the action of dilute acids.

Monosaccharides are classified according to the number of carbon atoms they possess:

Trioses = have three carbon atoms

Pentoses = have five carbon atoms

Hexoses = have six carbon atoms etc

The most important sugars are the hexoses.

Glucose is a hexose sugar (C₆H₁₂O₆), others include fructose and galactose

DISACCHARIDE (double sugars)

This is a sugar consisting of two linked monosaccharide molecules.

Through condensation they are bonded together and a molecule of water is removed. Examples of disaccharides are:

Maltose --------------- (glucose +glucose)

Sucrose ----------------- (glucose + fructose

Lactose ----------------- (glucose + galactose)

All disaccharides are soluble in water, have sweet taste and can be crystallized.

All disaccharides, except maltose do not reduce Benedict’s solution, hence are sometimes called Non-reducing sugars.

Sucrose is a very important sugar and the main way in which carbohydrates are transported in plants.

Sucrase

SUCROSE Glucose +Fructose

Enzyme

POLYSACCHARIDES ‘The starches’

Any of a group of carbohydrates composed of long chains of monosaccharide molecules. Polysaccharides may have molecular weights of up to several million and are often highly branched.

Cellulose contains about 3000 glucose molecules joined to form long chains.

All polysaccharides do not have a sweet taste and can be referred to as Non-sugars.

Starch, glycogen, cellulose, chitin and lignin are examples of polysaccharides.

Carbohydrates are stored in plants inform of starch.

Glycogen is a principal storage carbohydrate in animals, sometimes called animal starch

Cellulose is a highly insoluble polysaccharide occurring widely in plants. Cellulose makes up the cell wall of plants.

LIPIDS (fat and oils)

This is a diverse group of organic compounds occurring in living organisms, lipids include fats, oils and waxes.

Lipids are made up of elements carbon, Hydrogen and Oxygen; they however, differ from carbohydrates in containing a much smaller proportion of oxygen.

Lipids are insoluble in water, but soluble in organic solvents such as Benzene, chloroform, ethers, alcohols e.g. ethanol etc

The building blocks / basics units of a lipid are glycerol and fatty acids.

Synthesis of a lipid molecule by condensation of glycerol and fatty acids

Water (H₂o)

Condensation water (H₂o)

Water (H₂0)

One Glycerol 3 fatty acid Triglyceride 3 - water

Molecule. Molecules. (Fat) molecules.

In other words, a lipid molecule is formed when a glycerol molecule combines with

3 fatty acid molecules. During the process, 3 molecules of water are removed i.e. condensation occurs.

Lipids have several functions in living organisms. Fats and oils are a convenient and concentrated means of storing food energy in plants and animals.

Lipids act as a source of energy.

A given weight of lipids produces almost twice as much energy as an equivalent weight of carbohydrates. ( lipids: it is 38Kj per g as compared to only 17 KJ per

G for carbohydrate food)

• Lipids act as a source of metabolic water, on oxidation of fats; a lot of water is released. The body uses this water.
• Phospholipids and sterols, such as cholesterol are major components of plasma membranes. Fats occur in certain seeds such as groundnuts, castor oil, coconut, simsim, sunflower etc.

Waxes (simple lipids) provide vital water proofing for body surfaces, the waxes such as are found in leaves of plants serve as an outer protective covering, fruits or seeds.

Waxes are particularly common in xerophytes in which they reduce transpiration.

PROTEINS

A large group of organic compounds found in all living organisms.

Just like carbohydrates and lipids,

Proteins are made of elements carbon, hydrogen and oxygen however; proteins differ from them by containing nitrogen in addition, and sometimes phosphorus or sulphur or both.

Proteins may also contain the element Iron (Fe), for example in hemoglobin.

Proteins are very large compounds of molecular weight about 20,000 up to several millions, the basic unit /building block of proteins is the amino-acid.

There are 20 naturally occurring amino acids. Two amino-acids combine to form a dipeptide while more than two amino acid molecules combine to form a polypeptide. A protein is thus made up of polypeptide chains.

Proteins do no dissolve in water but form suspensions called Colloids.

Proteins can be classified according to their solubility in water, namely:

• Globular proteins and
• Fibrous proteins

Globular proteins are soluble, examples are Hemoglobin, albumen, fibrinogen, enzymes, antibodies, casein, hormones e.g. insulin. While fibrous proteins are insoluble e.g. keratin, which forms hair and finger nails.

Fibrous proteins are normally for strength and elasticity e.g. Collagen.

Fibrin is a fibrous protein involved in blood clotting.

Most proteins are denatured when heated beyond 40⁰C O² when subjected to strong acids or alkalis.

Proteins are amphoteric, and so can combine with both acidic and basic compounds.

Therefore proteins can combine with non-protein compounds to form conjugated proteins. Mucus and Hemoglobin are examples of conjugated proteins.

As structural compounds, proteins form blood plasma, cell membranes, muscle fibres e t c.

Proteins regulate physiological processes e.g. reproduction, growth, excretion e.g.

Proteins are composed of various proportions of the 20 naturally occurring amino acids in the polypeptide chain determines the shape, properties and hence biological role of the protein.

AMINO ACIDS

An amino acid is a water soluble organic compound that possess both a carboxyl (-COOH) and an amino (-NH₂) group attached to the same carbon atom,

Through the formation of peptide bonds, amino acids join together to form peptides or much longer chains, the polypeptides.

Of the 20-naturally occurring amino acids, the human body can synthesize 10 of them. These are known as Non-essential amino acids.

10 of them cannot be synthesized but the body, and must be supplied by the diet, therefore they are known as essential amino –acids.

ENZYMES

An enzyme is a protein that acts as a catalyst in bio chemical reactions.

Enzymes are thus, organic biological catalysts. Enzymes control the rate of metabolic reactions in living organisms without being changed in the process.

Living cells produce enzymes.

Some enzymes work within the cells of living organisms that produce them.

These are referred to as intracellular enzymes e.g. catalase in plant and animal tissues. Other enzymes are referred to as extra-cellular enzymes. They work outside the cells, which secrete them e.g. digestive enzymes.

The names of most individual enzymes and in - ase. It is a modern method of naming enzymes whereby suffix - ase is added to the name of the substrate (food type) or the reaction which the enzyme catalyses. Examples: Lactase, dehydrogenase etc. (see table below)

Substrate reactions and enzymes

Substrate	Enzyme
Lipids	Lipase
Lactose	Lactase
Maltose	Maltase
Sucrose	Sucrase
Protein	Protease
Hydrolysis	Hydrolase
Oxidation	Oxidase
Reduction	Reductase
Hydrogenation	Hydrogenase

Each enzyme is specific to a particular reaction; Enzyme activity is influenced by substrate concentration and by temperature and PH, which must lie within a certain range.

The molecule undergoing reaction (the substrate) binds to a specific active site on the enzyme molecule to form a short lived intermediate, which greatly increases the rate at which the reaction proceeds to form the product. (Read about the lock-and key hypothesis)

E + S ES P + E

Enzyme + Substrate Complex Product + Enzyme.

N.B The enzyme fits like a key in the lock. Enzymes do not form part of the products; they remain uncharged and can be used again. Enzymes are required only in small quantities.

Deficiency disease

Any disease caused by an inadequate intake of an essential nutrient in the diet, primarily vitamins, amino acids, and minerals.

Examples are:

• Scurvy = due to lack of Ascorbic acid

• Kwashiorkor = common in south East Asia and West Africa

• Beri beri = there’s wasting of muscles, and swelling of feet and legs.

• Pellagra = skin disorder, due to lack of vitamin B₂ (Nicotinic acid)

• Marasmus = due to starvation but in children, the diet lacks most types of food and there is total lack of energy (calories).

ANAEMIA

This is a condition, which arises when either there are too few red blood cells (erythrocytes) or the erythrocytes do not contain sufficient amounts of hemoglobin. Anemia often results from loss of blood or from a deficiency in the factors necessary to synthesize hemoglobin (e.g. Iron or erythrocytes (e.g. folic acid and Vitamin B₁₂).

PH SCALE:

PH is a unit or measure of acidity and alkalinity. pH values between 1 and 6 indicate acidity; pH values between 8 and 14 indicate alkalinity and a pH value of 7 indicate a neutral solution.

It is a logarithmic scale for expressing the acidity or alkalinity of a solution.

pH stands for potential of hydrogen the scale was introduced by S.P Sorensen (1868-1939)

WATER

Water is an important component of a balanced diet. A healthy human adult needs at least 3-4 litres of water in the body.

Water is made up of the elements Hydrogen and Oxygen in the ratio of 2:1 respectively.

The chemical formula for water is H₂O.Water forms up to about 70% of the total body mass in a healthy person.

IMPORTANCE OF WATER

Properties and functions of water include the following:

1. Water is a universal solvent. All metabolic reactions in the body can only take place in a water medium.

2. In water, absorbed food, wastes and hormones are transported in the body of animals. Water makes 90% of blood in mammals

3. Water activates enzymes for hydrolysis and digestion in general.

4. Water has a high boiling of 100^o C and ice has a low melting point of 0^oC, water provides an ideal environment for plant and animal life.

5. Water plays a role in temperature regulation through perspiration in animals, sweating in human beings and transpiration in plants. This cools down the organism through the loss of latent heat of vapourisation.

6. Water has a high surface tension. This means that water molecules can stick together and can form a continuous flow in the xylem vessels. (Review transport in plants – cohesive and adhesive forces for ascent of water).

7. Water is incompressible; therefore it provides turgidity, which is important in supporting living organisms, especially plants.

8. Water expands when it freezes; this means that its molecules are further apart in solid form (or ice), making it less dense than liquid water and therefore floats on water. This enables aquatic organisms in temperate climate to survive in water.

9. Water is transparent, this means that light can pass through it; this enables aquatic plants to carry out photosynthesis.

WORKSHEET II (FOOD TESTS)

FOOD TESTS AND EXPECTED RESULTS (i.e. positive results)

Food substance	Reagent and colour	Expected results i.e. positive results.
Starch	Iodine solution (brown /yellow colour)	Solution turns blue-black
Reducing sugar	Benedict’s solution or Fehling’s solution ( both are blue)	Blue to green to yellow to orange or brown precipitate
Non-reducing sugar	Dilute HCl (colourless) Dilute NaOH solution (colourless) Benedict’s or Fehling’s solution	The solution changes from blue to green, then yellow and finally orange/brown precipitate.
Proteins	Million’s reagent (colourless)	A white precipitate is formed which changes to a pink/brown solid or coagulation or precipitate on boiling.
	Beret’s test Copper II Sulphate (Blue ), Sodium hydroxide (colourless)	A purple colouration is formed
Lipids	i) Emulsion test Ethanol (colourless) Water (colourless) ii) A translucent mark/grease spot test. iii) Sudan III test. - Sudan III dye is orange powder.	- A creamy /milky emulsion is observed. - Translucent mark is observed. - Red droplets, observed, forming an emulsion, finally a red colour floats, separating from colourless water.
Vitamin C (Ascorbic acid)	DCPIP solution (Blue)	DCPIP is decolourised i.e. turns from blue to colourless.

TEACHING SYLLABUS

Section 3: Nutrition in plants and animals

Subtopic: Nutrient compounds

Week 1	Carbohydrates and food tests Introduction of proteins	3 Periods 1 Period
Week 2	Proteins, food tests and malnutrition. Lipids (fats and oils), Vitamins	Periods 1 Period
Week 3	Vitamins and minerals and deficiency diseases Introduce enzymes	Periods 1 period
Week 4	Enzymes and properties Enzyme experiments	Periods 3 Periods
Week 5	Water and its importance Introduce nutrition in animals; feeding methods in a meoba and insects	1 period 3 Periods

Sample Evaluation Questions

SECTION A

Multiple-choice questions:

Select the best alternative to each of the following questions:

1. Which elements make up carbohydrates?
   1. Carbon, hydrogen and nitrogen.
   2. Carbon, hydrogen and iron
   3. Oxygen, carbon and hydrogen
   4. Magnesium, hydrogen and carbon

2. Monosaccharides react with one another producing a molecule of water in a process known as:
   1. Hydrolysis
   2. Condensation
   3. Polymerization
   4. Hydration.

3. Which deficiency disease results from lack of vitamin C
   1. Beriberi
   2. Kwashiorkor
   3. Scurvy
   4. Marasmus.

4. Which of the following form building blocks for proteins?
   1. Glycerol and fatty acids
   2. Glucose
   3. Amino acids
   4. Galactose

5. Amino acids that cannot be synthesized by the body but must be supplied by the diet are referred to as
   1. Amphoteric proteins
   2. Essential amino acids
   3. Conjugated proteins
   4. Non-essential amino acids
6. Which of the following enzymes is NOT a carbohydrase?
   1. Amylase
   2. Lipase
   3. Maltase
   4. Sucrase.

7. Enzymes are biological catalysts produced by living cells. Which one is NOT

Correct about enzymes?

A. Speed up or slow down the rate of chemical reaction

B. Catalyse only one particular reaction.

C. They are not affected by temperature.

D. They function best at a specific pH (optimum)

8. Which of the following is not an enzyme?

A. Salivary amylase

B. Insulin

C. Maltase

D. Sucrase

9. The lock and key hypothesis explains how enzymes work. Given that the

Substrate is the lock and ………as the key.

A. Product

B. Substrate

C. Enzyme complex

D. Enzyme.

SECTION B.

Structured/Short Answer Questions

1. The information below was obtained from label of a frozen pizza ingredients

Wheat flour, cheese, yeast, hydrogenated vegetable oils, onion, salt, garlic, and ascorbic

Acid, Soya flour, peppers.

Nutritional information (typical values)

Per 100g Per slice

Energy 707KJ 745KJ

Protein 7.9g 8.3g

Carbohydrate 26.9g 28.3g

1. Which ingredient is in the largest amount? 1 mark
2. A 13-year-old girl needs 9000KJ per day what percentage of her daily energy needs would be supplied by a slice of a pizza? 3 marks
3. State three uses of proteins in the body 3 marks

2a) What is meant by the following terms?

1. Balanced diet
2. Digestion
3. Absorption

b) For each of the following substances, state

1. where it is produced
2. where it works
3. what it does

Pancreatic amylase, bile, pepsin, saliva

3. State three properties of enzymes

3 (a) In an experiment to determine the amount of vitamin C in a set of fruits the results in the table were obtained. Study the table and answer the questions that follow.

Fruit Juice	No. of drops of DCPIP
Orange	2
Lemon	5
Pineapple	14
Passion fruit	8

i) Which fruit has the highest amount of vitamin C?

ii) Which fruit has the lowest amount of vitamin C?

iii) Arrange the fruits in order of increasing concentration of vitamin C.

iv) State the importance of vitamin C in your diet.

(b) Draw up a table and fill in the local foods, source for the following vitamins A, C, D and vitamin B (complex)

4. a) Name two examples of monosaccharides.

b) Give the principle storage carbohydrate substance in

9. Animals

ii) Plants

c) The table below shows the nutrient compounds and their deficiency diseases. Study it and fill in the spaces to complete it.

Nutrient Compound	Deficiency disease
Carbohydrate
	Beriberi
Proteins
	Scurvy
Vitamin A

5. a) Name the three elements contained in all fats.

b) List three reasons why animals need fats in their diet

c) Give two food items that can provide fats in ones diet.

6. The graph below illustrates the effect of temperature on the rate of enzyme reaction

The graph above illustrates the effect of temperature on the rate of enzyme reaction.

a) State what happens:-

1. between A and B
2. at C
3. Between D and E

b) Explain what happens between A and B.

c) From the results of this experiment give your general conclusion

d) Give two more factors, other than the one shown above, that affect the rate of enzyme action.

e) i) Name an enzyme that gives similar results to those shown above in the graph.

ii) Name the glands, which produce this enzyme.

iii) State the action of this enzyme.

Answers to evaluation questions

Section A (multiple choice questions)

1. C
2. B
3. B
4. C
5. B
6. C
7. C
8. B
9. D.

Section B (Semi structured question answers)

1.a) Wheat flour

b) 1 slice of pizza provides 745 KJ

745 KJ are provided by 1 slice of pizza

Percentage provided by 1 slice

745 X 100

9000

Therefore the percentage supplied by a slice is 8.27%

c) Repair of worn out tissues

Formulation of enzymes/hormones

Growth/building of tissues

2. a. i) A balanced diet is one that contains all food nutrients in their right

proportions.

ii) Absorption is the process by which large insoluble food substances are

broken down into small absorbable particles.

iii) This is the process by which complex food substances are broken down

to simpler absorbable particles.

b)

Substance	Where produced	Where it works	What it does
Pancreatic amylase	Pancreas	Duodenum	Breaks down starch to maltose.
Bile	Liver	Duodenum ileum	Emulsifies fats and provides a suitable Ph for enzymes
Pepsin	Stomach wall	Stomach	Breaks down proteins to peptides
Saliva	Salivary glands	Mouth cavity	Contains salivary amylase that breaks down starch to maltose

3. a.

i) Pineapple

ii) Orange.

iii) Orange., Lemon, Passion fruit, Pineapple.

. iv) Prevents scurvy.

b)

Vitamin	Food Substance
A	Green vegetables, milk, Fish. Cod liver Oil and eggs.
B	Yeast, peas, beans, eggs, G-nuts, Liver, palm wine
C	Pawpaw, guavas, citrus fruits, Green vegetables, sweet potatoes
D	Milk, fish, margarine, cod liver oil, meat.

4. a) Glucose, Galactose,

b (i) Glycogen

(ii) Starch

(c)

Nutrient Compound	Deficiency disease
Carbohydrates	Marasmus
Vitamin B1	Beriberi
Proteins	Kwashiorkor
Vitamin C	Scurvy
Vitamin A	Xerophthalmia (Night blindness)

5.

(a) Carbon, Hydrogen and oxygen

b) They provide energy when oxidized

They insulate the body against heat loss

They form structural components of the cell membrane

c) Meat, fish, mutton, pork

6.

1. i). As the temperature increases (from A to B), the rate of enzyme reaction also increases.

ii) At C the rate of enzyme reaction reaches its maximum point (i.e. when

temperature is about 37^oC). This is the optimum for enzyme reaction.

iii) As the temperature increases, the rate of enzyme reaction (between D and E) decreases.

2. The rate of enzyme reaction increases with the rise in temperature until an

Optimum temperature is reached because the enzyme is activated. After that

rate of enzyme action decreases with the rise in temperature as the enzymes

are denatured.

c. Enzymes work best at an optimum Ph.

d. I) Particular degree of acidity/alkalinity, concentration of the substrate

ii) Ptyalin/Pepsin.

ii) Salivary glands/ Stomach wall

iv) Breaks down starch to maltose (a sugar)/ Breaks down proteins to

peptides.

Sample Practical Examination

1. You are provided with specimen K1, K2, K3 and K4.

(a) Observe each specimen carefully and record the major observable characteristic features of each specimen. K1,………………………………………………………………………………………………………………………………………………………………………………….

K2………………………………………………………………………………………………………………………………………………………………………………….

K3………………………………………………………………………………………………………………………………………………………………………………….

K4………………………………………………………………………………………………………………………………………………………………………………….

b) Using the characteristics features of each specimen you have observed, construct a simple biological key to identify the specimen.

………………………………………………………………………………………………………………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

…………………………………………………………………………………………

2. You are provided with substances M1 and M2. One is a mixture of an enzyme and food material while the other is only a food material. Carry out the following tests to identify the two food substances.

Test	Observation	Deduction
(i) To 1cm3 of substance M1 in a test tube add 2-3 drops of iodine solution.
(ii) To 1cm3 of substance M1 in a test tube add 2-3 drops of iodine solution.
(iii) Dip a piece of filter paper 5 mm * 5mm in substance M1 and transfer into 5cm3 of hydrogen peroxide in another test tube and observe for 5 minutes.
(iv) Repeat as above using substance M2

(a) (i) Substance M1 contains.

………………………………………………………………………………………………………………………………………………………………………………….

Give reasons. ………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………………………………………………………………………. (ii) Substance M2 contains

………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

Give reasons.

………………………………………………………………………………………………………………………………………………………………………………….

b) What was the effect of the enzyme on hydrogen peroxide?

………………………………………………………………………………………………………………………………………………………………………………….

………………………………………………………………………………………………………………………………………………………………………………….

Suggest the name of the enzyme.

…………………………………………………………………………………………-

INSTRUCTIONS FOR THE TEACHER.

SPECIMENS:

K1 is …………………lantana leaf

K2 is………………….jacaranda leaf

K3 is…………………..Soya / bean leaf

K4 is. …………………Potato leaf

M1 is 5 % starch solution.

M2 is 5 % sucrose solution