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Class 7 Science — Life processes in animals

Follow food through the alimentary canal and say what each part does, tell breathing from respiration, and match an animal to the way it takes in oxygen.

Name: ________________________

Before you start

The parts of the human respiratory system, from the nostrils down.

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  1. 1. Nostrils
  2. 2. Windpipe
  3. 3. Lung
  4. 4. Rib cage
  5. 5. Diaphragm

Air comes in at the nostrils, down the windpipe, and into branches that end in tiny balloon-like sacs called alveoli inside the lungs. The rib cage guards the lungs; the dome-shaped diaphragm below them does the pulling.

  1. 1.Inhaled air is nearly 21 per cent oxygen; exhaled air is nearly 16 per cent oxygen. How many percentage points of oxygen were taken from the air? Answer with a number.

  2. 2.Why is the inner lining of the small intestine covered in thousands of finger-like projections?

    • a) They stop acid from the stomach reaching the intestine wall
    • b) They increase the surface area, so nutrients are absorbed efficiently
    • c) They grip the food and stop it moving on too fast
    • d) They make the digestive juices the small intestine needs

  3. 3.The large intestine is shorter than the small intestine. Why is it called large?

    • a) It does more of the digesting than any other part
    • b) It holds more food at one time than the stomach
    • c) It is wider than the small intestine
    • d) It was discovered before the small intestine was

  4. 4.What does the acid in the stomach do, besides helping to break down proteins?

    • a) It turns starch into sugar
    • b) It kills many harmful bacteria
    • c) It absorbs nutrients into the blood
    • d) It stores the food until the intestine is ready

  5. 5.Put the parts of the alimentary canal in the order food passes through them, starting at the mouth.

    • Large intestine
    • Rectum
    • Oesophagus
    • Stomach
    • Small intestine
    • Mouth
    • Anus

  6. 6.The finest branches inside the lungs end in tiny balloon-like sacs, and it is across their thin walls that gases are exchanged. What are those sacs called?

  7. 7.A cow brings partially digested grass back up to its mouth and chews it thoroughly. What is that process called?

  8. 8.What is the difference between breathing and respiration?

    • a) They are two words for the same process
    • b) Breathing happens in the lungs; respiration happens in the nose
    • c) Breathing is what animals do; respiration is what plants do
    • d) Breathing is a physical process moving air in and out; respiration is a chemical process using oxygen to release energy from food

Answer key — Class 7 Science — Life processes in animals

  1. 1. 5
  2. 2. b) They increase the surface area, so nutrients are absorbed efficiently
  3. 3. c) It is wider than the small intestine
  4. 4. b) It kills many harmful bacteria
  5. 5. 1. Mouth 2. Oesophagus 3. Stomach 4. Small intestine 5. Large intestine 6. Rectum 7. Anus
  6. 6.
    • alveoli
    • alveolus
  7. 7. rumination
  8. 8. d) Breathing is a physical process moving air in and out; respiration is a chemical process using oxygen to release energy from food