Gas exchange in single-celled organisms, insects and fish Quiz
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5 questions, one answer each
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1. Which structure of an insect is the site of gas exchange with respiring cells?
- A. Spiracle
- B. Trachea
- C. Tracheole
- D. Cuticle
2. Why can a fish absorb more oxygen with counter-current flow than parallel flow?
- A. Water flows faster
- B. The blood contains more haemoglobin
- C. The lamellae are thicker
- D. Equilibrium is never reached because a gradient is maintained along the lamella
3. Why does an insect close its spiracles when it is at rest?
- A. To reduce water loss by evaporation
- B. To increase oxygen uptake
- C. To trap carbon dioxide
- D. To stop tracheoles collapsing
4. Why is a single-celled organism able to rely on diffusion across its surface?
- A. It has a small surface area to volume ratio
- B. It has a waterproof surface
- C. It has a short diffusion distance and large surface area to volume ratio
- D. It has a circulatory system
5. Water entering a fish's gills is 80% saturated with oxygen and leaves 20% saturated. What percentage of the oxygen is absorbed?
- A. 60%
- B. 75%
- C. 25%
- D. 80%