Question

Flatworms differ from roundworms in possessing

• A. Solid mesoderm
• B. Bilateral symmetry
• C. Metamorphosis
• D. Triploblastic body

Answer 1

Answer: (A)

Solid mesoderm

Roundworms are pseudocoelomate which means they have a body cavity which is not completely surrounded by mesoderm. The cavity is lined with mesoderm only on the ectodermal side. Thus, although organs are held in place loosely, they are not as well organized as in a coelomate. So, roundworms do not have solid mesoderm. Flatworms have solid mesoderm, ectoderm and endoderm. So the correct answer is 'Solid mesoderm'.