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Gaseous exchange in annelids is more advanced and efficient compared to flatworms because?

Gaseous exchange in annelids is more advanced and efficient compared to flatworms because?
Take Free Practice Test On 2026 JAMB UTME, Post UTME, WAEC SSCE, GCE, NECO SSCE
  • A The cells of their epidermis have no blood capillaries
  • B They have well developed respiratory structures
  • C Their cylindrical shape gives high surface area to volume ratio
  • D Their surface area to volume ratio is very low
Correct Answer: Option C
Explanation:
In simple organisms, such as cnidarians and flatworms, every cell in the body is close to the external environment.
Their cells are kept moist and gases diffuse quickly via direct diffusion. Flatworms are small, literally flat worms, which “breathe” through diffusion across the outer membrane.
Annelids have a closed circulatory system; the blood is entirely contained in vessels.
Annelids have no lungs, although many species have simple gills.

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