Question

1. how do nematodes differ from annelids?

nematodes are segmented like annelids.
nematodes have a pseudocoelom.
nematodes have a closed circulatory system.
nematodes cannot regenerate body parts.

Explanation:

• Nematodes are segmented like annelids: Incorrect. Annelids are segmented (metameric), while nematodes are unsegmented.
• Nematodes have a pseudocoelom: Correct. Nematodes have a pseudocoelom (body cavity not fully lined by mesoderm), while annelids have a true coelom (fully lined by mesoderm).
• Nematodes have a closed circulatory system: Incorrect. Nematodes lack a circulatory system (gas and nutrient exchange occurs via body wall and pseudocoelomic fluid), while annelids (like earthworms) have a closed circulatory system.
• Nematodes cannot regenerate body parts: Incorrect. While annelids (e.g., some polychaetes) have good regenerative abilities, some nematodes (e.g., Caenorhabditis elegans) also show limited regenerative capacity in certain tissues.

Answer:

Nematodes have a pseudocoelom.