Ascaris is characterized by
- presence of true coelom but absence of metamerism
- presence of true coelom and metamerism (metamerisation)
- absence of true coelom but presence of metamerism
- presence of neither true coelom nor metamerism
Answer
(4) presence of neither true coelom nor metamerism
Solution
As per NCERT, the body cavity of aschelminthes is not lined by mesoderm; instead the mesoderm is present as scattered pouches between the ectoderm and endoderm. Such a body cavity is called pseudocoelom.
⇒ Ascaris (roundworm) belongs to Aschelminthes; its body is circular in cross-section and unsegmented.
∵ It has a pseudocoelom (no true coelom) and its body shows no metameric segmentation,
∴ Ascaris shows neither true coelom nor metamerism.
Answer: (4)