Nutrition in Animals

Animal nutrition includes the nutrient requirement, the mode of intake of food and its use in the body. Food is taken in by different methods: snails scrape, ants chew, mosquitoes suck blood, and starfish push out their stomach to eat clam meat. Digestion breaks down complex food into simple, soluble substances. In humans, food passes through the alimentary canal: buccal cavity, oesophagus, stomach, small intestine, large intestine, rectum and anus. Teeth chew food, and saliva begins changing starch into sugar. The stomach releases hydrochloric acid, mucus and digestive juices that act on proteins. The small intestine, about 7.5 m long, receives bile from the liver, the largest gland, and pancreatic juice. Finger-like villi absorb the digested food into the blood, and it is used in assimilation. The large intestine absorbs water and salts, and undigested waste is removed by egestion. Grass-eating ruminants such as cows store food in the rumen and later chew the cud, with bacteria digesting cellulose. Amoeba captures food with pseudopodia and digests it in a food vacuole.

Detailed Worksheet: Nutrition in Animals Section A - Definitions (10 marks) 1. Define ingestion, digestion, absorption, assimilation and egestion. (2 marks) 2. What are milk teeth and permanent teeth? (2 marks) 3. What are villi? State their function. (2 marks) 4. What are ruminants? What is meant by chewing the cud? (2 marks) 5. What are pseudopodia? How does Amoeba use them? (2 marks) Section B - Calculations and Applications (15 marks) 6. Name the four types of teeth in humans and the function of each. How many of each type does an adult with 32 teeth have? (3 marks) 7. Match each organ with its role: salivary glands, stomach, liver, pancreas, small intestine, large intestine. (3 marks) 8. State the role of (i) hydrochloric acid in the stomach (ii) mucus in the stomach (iii) bile. (3 marks) 9. The small intestine is about 7.5 m and the large intestine about 1.5 m long. (i) How many times longer is the small intestine? (ii) Why is the large intestine called "large" though shorter? (iii) Why is the small intestine so long and coiled? (3 marks) 10. Name the way of feeding in each: (i) snail (ii) mosquito (iii) eagle (iv) starfish (v) honeybee (vi) python. (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of the human digestive system showing the buccal cavity, oesophagus, stomach, liver, gall bladder, pancreas, small intestine, large intestine, rectum and anus. (4 marks) 12. Draw a labelled diagram of the stomach of a ruminant showing the rumen and the path of food. (3 marks) 13. Draw a labelled diagram of Amoeba showing pseudopodia, nucleus and food vacuole, with steps of capturing food. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Boojho chewed a piece of boiled rice for 3 to 5 minutes and found that it tasted sweet. (i) Why did it taste sweet? (ii) Which juice caused this? (iii) Design a test with iodine solution to show the change from starch. (iv) What will be seen in a tube of rice with saliva and in one without? (5 marks) 15. A child suffers from repeated loose motions. (i) Name this condition. (ii) Why can it be fatal? (iii) What first aid is given and how is it made at home? (iv) Name two causes. (5 marks) 16. Tooth decay is common among children who eat many sweets. (i) How do bacteria cause tooth decay? (ii) Why are chocolates and soft drinks harmful? (iii) List three ways to prevent tooth decay. (iv) Why can't humans digest cellulose while cows can? (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Label diagrams clearly and use correct names for parts of the alimentary canal.