Life Processes in Animals – Class 7 Science notes, important questions and MCQs

Chapter overview

Animals need food, oxygen and a way to remove wastes. Digestion, respiration, circulation and excretion keep them alive.

Nutrition and digestion

• Humans: mouth (teeth, saliva) → oesophagus → stomach (acid, enzymes) → small intestine (digestion completed, absorption by villi) → large intestine (water absorbed).
• Grass-eating animals like cows chew the cud (ruminants); amoeba takes food with false feet.

Respiration and circulation

• Breathing: lungs in humans; gills in fish; spiracles and tracheae in insects; skin in earthworms.
• Heart pumps blood; arteries carry blood away from the heart, veins bring it back.
• Blood has red cells (carry oxygen), white cells (fight germs), platelets (clotting).

Excretion

• Kidneys filter blood and make urine; sweat also removes some wastes.
• Animals excrete different wastes: fish give out ammonia, birds and lizards give out uric acid, humans give out urea.

Key terms

Villi

finger-like projections in the small intestine that absorb food

Ruminant

animal that chews the cud, like a cow

Excretion

removal of wastes from the body

Formulas

• Glucose + oxygen → carbon dioxide + water + energy

Important questions with answers

Quick revision

• Digestion completes in the small intestine.
• Fish breathe through gills.
• Kidneys make urine.

Exam tips

• Pulse rate shows heartbeats per minute (about 72 at rest).
• Arteries have thick walls because blood flows with high pressure.

Practice MCQs

1. Digestion of food is completed in the

   1. stomach
   2. mouth
   3. large intestine
   4. small intestine
   Show answer

   Answer: (d) small intestine. Small intestine.

2. Fish breathe with

   1. lungs
   2. spiracles
   3. skin only
   4. gills
   Show answer

   Answer: (d) gills. Gills.

3. Which blood cells fight germs?

   1. red blood cells
   2. plasma
   3. platelets
   4. white blood cells
   Show answer

   Answer: (d) white blood cells. WBCs.

4. The organ that filters blood to form urine is the

   1. liver
   2. kidney
   3. lung
   4. heart
   Show answer

   Answer: (b) kidney. Kidney.

5. Digestion of food is completed in the

   1. stomach
   2. mouth
   3. large intestine
   4. small intestine
   Show answer

   Answer: (d) small intestine. With bile and pancreatic juice.

6. Why do cows chew the cud?

   1. grass is hard to digest, so they swallow quickly and chew it later
   2. they have no teeth
   3. to sleep better
   4. to drink water
   Show answer

   Answer: (a) grass is hard to digest, so they swallow quickly and chew it later. Ruminant digestion.

7. Normal pulse rate of a resting adult is about

   1. 30 per minute
   2. 10 per minute
   3. 150 per minute
   4. 72 per minute
   Show answer

   Answer: (d) 72 per minute. About 72.

8. Cows chew the cud because

   1. they have no teeth
   2. their stomach is small
   3. they are always hungry
   4. partly digested food returns from the rumen to the mouth
   Show answer

   Answer: (d) partly digested food returns from the rumen to the mouth. Ruminants.