i)

Digestive enzyme is a chemical/biological catalyst that help in breaking down food substances in the body

ii)

Examples of digestive enzymes in humans

1. Salivary amylase/Ptyalin
2. Pancreatic amylase
3. Maltase
4. Sucrase
5. Proteases/pepsin/rennin/trysin/erepsin/peptidase
6. Lipases

i)

Constipation is the difficulty in freeing/expelling faces from the bowels regularly.

OR

Constipation is the difficulty in defecating regularly.

OR

Constipation is the irregular and difficult passage of faeces.

ii)

Ways by which constipation can be prevented

1. Take meals at regular times
2. Do not overeat
3. Undertake a good amount of exercise
4. Take in enough water
5. Eat plenty of fruits, vegetables and rouphages
6. Free bowels regulary/attend nature's call regularly

i)

Digestion is the breaking down of complex or insoluble food substances into simple and absorbable forms in the body of mammals.

ii)

How food is digested in the stomach

1. Slightly alkaline food enters the stomach
2. The walls of the stomach produce/secrete gastric juice which is mixed with the food
3. The gastric juice contains dilute hydrochloric acid and protein digesting enzymes (proteases)
4. The dilute hydrochloric acid provides/creates acidic medium/condition in the stomach
5. The enzymes break down the large protein molecules into simpler units (amino acids)
6. Only protein molecules are digested in the stomach

(i)

Carbohydrates → glucose

(ii)

Proteins → amino acids

(iii)

fats → fatty acid and glycerol

(i)

Meat (Protein) = Amino acids

(ii)

Cassava (Carbohydrate) = Glucose

(iii)

Palm-oil (Fat & Oil) = Faty acids/glycerol

(i)

Digestion of a morsel of kenkey in the mouth

1. The morsel of kenkey is chewed, mixed with saliva so that it can be easily swallowed
2. The ptyalin/enzyme in saliva acts on the starch present in the kenkey and changes it to maltose

(ii)

The parts of the digestive system of humans listed in order

Mouth → oesophagus/gullet → stomach → duodenum → ileum → colon → rectum → anus

i)

Differences between egestion and digestion in nutrition

Egestion is the removal of undigested food/semi-solid or waste/faeces from the anus while digestion is the breaking down of food into smaller building blocks or components that can be absorbed into the blood stream.

ii)

End-products of digestion

1. Glucose/simple sugar
2. Amino acids
3. Fatty acids and glycerol
4. Final results obtained after breakdown of complex food substances