IGCSE Biology Paper-1: Specimen Questions with Answers 148 - 148 of 208

Question 148

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Question

MCQ▾

Which of the following animal shown here is Not an Annelida?

Features of Annelids

Features of Annelids

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Choices

Choice (4)
a.C
b.A
c.D
d.B

Answer

a.

Explanation

Features of Annelids

  • Body segmented. Segments ring –shaped
  • True segmentation (Metamerism) present. Number of segments fixed, new segments not added and old ones not removed. Segments (true) called metameres.
  • Free living or parasite
  • Triploblastic and bilaterally symmetrical
  • Locomotory structures – Setae and Parapodia
  • Alimentary canal well differentiated with mouth and anal opening
  • Respiration through gills or branchia, cirri and skin
  • Excretory structure- Nephridia

Blood vascular system present and has developed for the first time. Blood pigment is dissolved in plasma. The RBCs are absent. The blood vascular system is OPEN OR CLOSED TYPE. Out of 4-major types of respiratory (blood) pigments, i. e. Hemoglobin, Hemerythrin, Chlorocruorin and Hemocyanin, the first three are present in Annelida.

Hemocyanin is absent in annelids but is present in molluscs and arthropods.

Examples: - Neanthes or Nereis (Rug worm or clam worm or sand worm, Chaetopterus (Paddle worm) – shows bioluminescence, Aphrodite (Sea mouse), Arenicola (Lug worm) Sabella, Polygyrids, Pheretima (Earthworm), Lumbricus (European earthworm), Mega scolex (South Indian earthworm), and Tubifex, Hirudinaria (Leech), Hirudo (European leech); Pontobdella- ectoparasite on fishes.