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The part labelled III acts as…

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Use the diagram to answer the question that follows

The part labelled III acts as

The part labelled III acts as

A. water outlet

B. food strainer

C. exchange surface

D. blood transporter




The above structure is that of a fish gill.

The part labelled I is called gill arch; its function is to offer support and frame on which the filaments and rakers are attached.

The part labelled II is called gill rakers; its function is to prevent escape of food through the slits, and damage to the gill.

And the part labelled III is called gill filaments; its function is to provide a good surface area where gases, water, acids, and ions are exchanged.

Now for the right answer to the above question:

  1. The gill filaments are not responsible for letting water out of the gill. So, A is incorrect.
  2. The gill rakers are the food strainers and not the filaments . B is also incorrect.
  3. The gill filaments offer a good surface area for effective exchange of materials. So, C is correct.
  4. D is incorrect; the filaments are not blood transporters.


You may please note that:

  • Exchange of materials such as water, gasses, carbon dioxide, oxygen, ammonia, acids and ions, occur in the gill filaments.

Use the questions and answers session to raise further questions and deal more on this topic…

/ culled from 2017 JAMB-UTME biology question 32 /

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