Question

The distinguishing feature of an annelida is

• A. Pseudocoelom and flame cells
• B. Pseudocoelom and longitudinal muscle in the body wall
• C. Flame cells and longitudinal muscle in the body wall
• D. Metameric segmentation and true coelom

Answer 1

The correct option is D

Metameric segmentation and true coelom

The correct option is D:

Explanation of the correct option:

Option D:

1. Annelids belong to the phylum Annelida under the kingdom Animalia.
2. These are bilaterally symmetrical invertebrate organisms found in aquatic as well as terrestrial environments.
3. Their metameric segmentation and presence of true coelom distinguish them from any other organism.
4. Metameric segmentation is the division of the body into segments by the repetition of organs and tissues at intervals along the body of an organism.
5. True coelom refers to a fluid-filled cavity between the outer wall and the gut lining.

Explanation of the incorrect option:

Option A:

Pseudocoelom (false cavity) and flame cells ( specialized excretory cells functioning as kidneys) are the distinguishing features of phylum Nematoda (nemathelminthes)

Option B:

Pseudocoelom (false cavity) and longitudinal muscle in the body wall are also the characteristics of the phylum Nematoda.

Option C:

Flame cells and longitudinal muscle in the body wall are again a distinguishing feature of phylum Nematoda.

Final answer: The distinguishing feature of an Annelida is metameric segmentation and true coelom.