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JAMB Biology 1980 Question 19

Question 19

Transport in Animals

Fig. 2: Vertical section through the heart
Why is the part labelled 5 thicker than 6?

Diagram for this question
  1. A.5 is the left ventricle and 6 the right ventricle
  2. B.6 is the left ventricle and 5 the right ventricle
  3. C.5 receives blood from the left auricle and 6 from the right
  4. D.5 pumps blood round the body and 6 pumps blood only into the lungs
  5. E.5 deals with oxygenated blood and 6 deoxygenated blood.
Show the answer and explanation

Answer: D (5 pumps blood round the body and 6 pumps blood only into the lungs)

Explanation

The left ventricle (5) must pump blood all round the body, so it has a thicker muscular wall than the right ventricle, which pumps only to the lungs.