(a) (i) "The length of the small intestine in various animals depends on the food they eat." Justify the statement. (ii) Discuss the role of the…

Animals (Herbivores) eating grass need a longer small intestine to digest cellulose. Meat is easier to digest, hence meat eating animals (Carnivores) have shorter small intestine.

Role of Pancreas - Secrete pancreatic juice which contains trypsin for digesting proteins, lipase for breaking down emulsified fats.

Role of Bile- Bile emulsifies fats and makes the medium alkaline in the small intestine so that pancreatic enzymes can act.

The inner lining of the small intestine has numerous finger-like projections called villi which increase the surface area for absorption of food. The villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body.

'Rings of cartilage' ensures that the air passage does not collapse in absence of air.

Ribs are lifted → Diaphragm flattens → Chest cavity become larger → Air is sucked into the lungs (Alveoli) and we breathe in

Due to lack of oxygen in our muscle cells (anaerobic respiration), pyruvate is converted into lactic acid, build-up of lactic acid in our muscles causes cramps.