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Difficulty: HardExcretion and Excretory Organs

In an evolutionary study of excretory mechanisms across animal phyla, biological specimens were categorized by their specialized excretory structures and principal nitrogenous waste products. Which of the following combinations correctly matches the organism, its excretory organ, and its primary nitrogenous waste?

  1. Earthworm — Nephridia — UreaAnswer
  2. B
    Planarian — Nephridia — Ammonia
  3. C
    Prawn — Malpighian tubules — Uric acid
  4. D
    Tapeworm — Green glands — Ammonia

Answer

Earthworm — Nephridia — Urea
The earthworm (phylum Annelida) utilizes nephridia (metanephridia) distributed segmentally throughout its body to extract nitrogenous waste from coelomic fluid and blood, excreting primarily urea and ammonia.

Step-by-Step Solution

1
Identify the excretory organ and primary waste product of an earthworm (Annelida)
Annelids possess segmentally arranged excretory structures called nephridia and excrete nitrogenous waste primarily as urea (and ammonia in moist soil).
Nephridia filter coelomic fluid and blood to reabsorb essential ions while excreting nitrogenous waste products like urea.
2
Evaluate the excretory structures of the remaining invertebrate groups to identify misattributions
Planaria use flame cells (protonephridia); prawns use green glands (antennal glands); tapeworms use flame cell units.
Matching each organism to its true phylogenetic excretory organ confirms that the other options contain structural misattributions.

Key Concept

Comparative Invertebrate Excretory Organs and Waste Products
Estimated Time:1m 30s
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Topics

Excretion and Excretory Organs

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