Question

Difficulty: EasyExcretion and Excretory Organs

Which of the following excretory structures is characteristic of flatworms such as *Planaria*?

  1. Flame cellsAnswer
  2. B
    Nephridia
  3. C
    Malpighian tubules
  4. D
    Contractile vacuoles

Answer

Flame cells are the characteristic excretory structures found in flatworms (Platyhelminthes).
Flame cells are cilia-bearing cells involved in excretion and osmoregulation specifically in flatworms like *Planaria*.

Step-by-Step Solution

1
Identify the taxonomic group of the target organism.
*Planaria* is a free-living flatworm belonging to the phylum Platyhelminthes.
Excretory structures vary across invertebrate phyla.
2
Match the phylum to its specialized excretory organ.
Platyhelminthes use flame cells (protonephridia) to remove metabolic wastes and regulate water balance.
Flame cells feature beating cilia that draw fluid into excretory tubules for waste elimination.

Key Concept

Excretory structures in invertebrate phyla
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