chapter 6

ANSWERS

Activity 1

a) (i) ingestion

(ii) digestion

(iii) absorption

    (iv) assimilation

b)

Enzymes	Reaction
Salivary amylase	Starch + water → maltose
pepsin	Protein + water  → polypeptides
rennin	casienogen  → casein
Pancreatic amylase	Starch + water → maltose
trypsin	polypeptides + water → peptides
lipase	Lipid + water→ glycerol + fatty acids
erepsin	Peptides + water → amino acids
maltase	Maltose + water → glucose
sucrase	Sucrose + water → glucose + fructose
lactase	Lactose + water → glucose + galactose
lipase	Lipid + water→ glycerol + fatty acids

c)  saliva

     gastric juice

     pancreatic juice

     bile

     intestinal juice

Activity 2

a)  X: glucose

     Y: amino acids

b) amino acids, glucose, B, C

     fatty acids, glycerol, A, D, E, K

c)  Excess amino acids are broken down in the liver

The liver cell remove harmful substances from the blood or convert them to compounds which are less toxic

Activity 3

Stomach, caecum

Stomach, cellulase, caecum, cellulose

Four, rumen, reticulum, omasum, abomasums, one

Short, long, large

Rumen, reticulum, mouth, chewed, omasum, twice, eat

Objective items

1   C

2   D        

3   B

4   B

5   B        

Structured questions

a) Margarine

b) It consists of more than 95% lipid. The energy released from the oxidation of 1 g

of lipid is twice the amount of energy released from the oxidation of 1 g of

carbohydrates or protein.

c) Egg. Growing children need protein. Egg is chosen even though chicken meat has

more protein because egg also contain vitamin A and D. Vitamin A is needed for

growth and healthy skin while vitamin D is needed for building strong bone and

teeth .

d) Lipid and protein

e) Carbohydrate and vitamin C

f) Bread and banana

g) Iron is needed to synthesise haemoglobin in the red blood cells.

h) Anemia

Essay Question

1a)  The processing must be able to:

• Prolong the shelf-life of food  -  preventing all micro-organisms from spoiling the

      food.

• Maintain the original taste of the food
• Maintain the original form of the food
• Preserve its nutritional content.
• Enhance the freshness of the food
• The food additives must not be a healthy risk.
• The method is not too technical or too expensive         [2 marks each=10]                                                                              

b) Increase local food production by introducing and/or popularizing new types of

    food such as ulam, mushroom, fresh water fishes, rabbit meat and ostrich steak.

                                                                                                                  [5 marks]

Using new methods in food production:

• Increasing local rice production by introducing better rice varieties.
• Using hydrophonic and aerophonics.
• Breeding animals to increase the meat and dairy products.
• Using tissue culture in producing better crops.
• Using genetic engineering to develop better food from plants and animals.