Skeletal systems and movement — A/L Biology

How do I practise Skeletal systems and movement?

1 question with a worked solution

1. Which skeletal support system relies on an incompressible fluid enclosed in a closed body compartment against which antagonistic muscle layers exert pressure to effect locomotion?
   1. A) Hydrostatic skeleton
   2. B) Chitinous exoskeleton
   3. C) Endochondral endoskeleton
   4. D) Calcareous shell
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   Correct answer: A) Hydrostatic skeleton

   A hydrostatic skeleton consists of fluid under pressure in a closed body cavity (e.g., coelom in annelids like the earthworm). Alternating contractions of circular and longitudinal muscles against the incompressible hydrostatic fluid generate peristaltic waves for movement.

   Show worked solution

   Step 1: Review animal skeletal systems: Exoskeleton (arthropods), Endoskeleton (vertebrates), Hydrostatic skeleton (annelids, cnidarians). Step 2: Fluid-filled cavity under muscular tension = hydrostatic skeleton. Answer: Hydrostatic skeleton.
   Modelled on: the A/L Biology examination pattern

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Where does Skeletal systems and movement fit in the syllabus?

Year 2 · Term 1