MCQ
“Shell of mollusc is produced by its
- ARadula
- BThorax
- ✓Mantle
- DAbdomen
✓
Answer
Correct option: C.
Mantle
c
(c)Mantle secrets a calcareous shell which is generally external but may be internal an supportive or absent.
(c)Mantle secrets a calcareous shell which is generally external but may be internal an supportive or absent.
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(i) Lower invertebrates like sponges, coelenterates, flatworms, etc., exchange O2 with CO2 by simple diffusion over their entire body surface.
(ii) Earthworms use their moist cuticle for exchange O2 with CO2.
(iii) Insects have tracheal tubes to transport atmospheric air within the body.
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