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Year 8 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.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?

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

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

  4. 4.Sort each animal by the part of its body that takes in oxygen.

    Groups: Breathes with lungs · Breathes with gills · Breathes through moist skin

    • Earthworm
    • Snake
    • Tadpole
    • Lion
    • Fish

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

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

  6. 6.Respiration uses oxygen to break down glucose. What comes out of it?

    • a) Glucose and energy, with nothing given off
    • b) Carbon dioxide and starch
    • c) Oxygen, water and starch
    • d) Carbon dioxide, water and energy

  7. 7.A frog begins life as a tadpole in water and grows into an adult that spends time on land. How does its breathing change?

    • a) The tadpole uses gills; the adult uses lungs on land and its skin in water
    • b) The tadpole uses lungs; the adult uses gills
    • c) It uses its skin throughout, and the lungs do nothing
    • d) It uses gills throughout, in water and on land alike

  8. 8.Tap the part of this alimentary canal where most of the digested nutrients are absorbed into the blood.

    Write the number of the part.

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Answer key — Year 8 Science — Life processes in animals

  1. 1. 5
  2. 2.
    • alveoli
    • alveolus
  3. 3. d) It kills many harmful bacteria
  4. 4. Lion → Breathes with lungs; Snake → Breathes with lungs; Fish → Breathes with gills; Tadpole → Breathes with gills; Earthworm → Breathes through moist skin
  5. 5. c) It is wider than the small intestine
  6. 6. d) Carbon dioxide, water and energy
  7. 7. a) The tadpole uses gills; the adult uses lungs on land and its skin in water
  8. 8. 4 — Small intestine