Chapter 24, Problem 19A

Summary Introduction

Introduction:

The evolutionary tree is arranged like a family tree, and the branches reflect the phylogeny of species. The trunk shows the earliest animals and the branches reflect the evolution of the main phyla of animals from a common ancestor. The branching points on the evolutionary tree mark anatomical features in the animal's body plans.

Answer to Problem 19A

Correct answer :

The correct answer is option (C) a coelom, protostome development, and segmentation

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) a coelom, protostome development, and segmentation. In the evolutionary tree, the characteristics of an earthworm have a coelom, protostome development, and segmentation which do not found in a flatworm. Flatworm is an acoelomate animal. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) a coelom, a body cavity, bilateral symmetry, and no tissues. In the evolutionary tree, both earthworm and flatworm are bilateral symmetry and they have tissues. A body cavity and a coelom are found only in earthworm. So, this is an incorrect option.

Option (B) a coelom and segmentation. In the evolutionary tree, an earthworm has a coelom, protostome development, and segmentation which do not found in a flatworm. So, this is an incorrect answer.

Option (D) a pseudocoelom, body cavity, and bilateral symmetry. In the evolutionary tree, both earthworm and flatworm are bilateral symmetry but they are not pseudocoelomates. Body cavity is found only in an earthworm. So, this is an incorrect answer.

Conclusion

Based on the evolutionary tree, a coelom, protostome development, and segmentation are found in an earthworm but not in flatworm. Hence, the correct answer is Option (C) a coelom, protostome development, and segmentation