Chapter 25, Problem 26A

Summary Introduction

Introduction :

The phylogenetic tree can be defined as the linear representation of the evolutionary relationship between the organism. It is used to determine the similarity and the difference between the evolution of the organism.

Answer to Problem 26A

Correct answer :

Option (C).

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) Annelids. The point of emergence of annelids and the mollusks is same and they share the greatest number of recent common ancestors. Hence, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) nematodes. The nematodes are the round worms and the nematodes and mollusks share different source of origin, which means they do not share a very close relation. Hence, it is an incorrect answer.

Option (B) echinoderms. The echinoderms are the deuterostomes and the mollusks are protostomes, which means they do not share the most recent common ancestor. Hence, it is an incorrect answer.

Option (D) chordates. The chordates are the deuterostomes and the mollusks are protostomes, which means they must have evolved from coelomate ancestor, but they did not emerged at the same time and do not share the latest common ancestor.Hence, it is an incorrect answer.