The respiratory surface of unicellular organisms is__________?
Correct answer: B. Cell membrane
- A. Specific organ
- B. Cell membrane
- C. Cell wall
- D. Nuclear membrane
Explanation
A unicellular organism has no specialised respiratory organ, so gases diffuse directly across its cell membrane. Students may choose the cell wall because it is an outer covering, but the cell wall is not the selectively permeable surface through which respiratory exchange mainly occurs.
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