Question

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups—Lophotrochozoa and Ecdysozoa. What does this finding suggest? _____ Select one: a. These two subgroups have a common ancestor that was a deuterostome. b. The protostomes are a polyphyletic group. c. Division of these two groups occurred after the protostome developmental sequence appeared. d. The lophotrochozoans are monophyletic.

Answer 1

Answer:

c. Division of these two groups occurred after the protostome developmental sequence appeared.

Explanation:

• Protosomes are such types of organisms in which the mouth part developed first during embryonic development.
• Those animals in which anus develop first are known as deuterostomes.
•  This differentiation takes place during the embryonic development of the organisms.
• Since lophotrochozoan and Ecdysozoa both are protostomes animals and categorized on the basis of molecular evidence.
• Thus these two groups were formed after the appearance of the protostomes.