SPM Biology 2018, Paper 2 (Question 5 & 6)

Question 6:
(a) Diagram 6.1 shows a gaseous exchange in the alveolus.

Diagram 6.1

Explain how oxygen is transported to the body tissues for cellular respiration. [4 marks]

(b)

Based on the statement above, suggest and explain how to keep our lungs healthy. [6 marks]
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(c) Diagram 6.2.1 and 6.2.2 show the respiratory organ from two different organisms.


Explain similarities and differences in structures of the respiratory organ between the two organisms. [10 marks]

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Answer:
(a)
- Oxygen gas in the alveoli is at higher partial pressure / higher concentration than in blood.

- Oxygen molecules diffuse across epithelium of alveoli and blood capillaries into blood.

- Oxygen binds with haemoglobin in the red blood cells / erythrocytes to form oxyhaemoglobin.

- The oxygenated blood is then transported from the lungs to cells of body tissues.

- In the tissues, oxyhaemoglobin dissociates into oxygen and haemoglobin.

- Oxygen diffuses down a concentration gradient across the epithelia of blood capillaries into the cells of body tissues.

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(b)



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(c)


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