Chapter 25, Problem 3STP

Summary Introduction

Introduction:

The Annelida is a group of segmented worms. The Nematoda is a group of roundworms. The Platyhelminthes are the flatworms. The Rotifera is the group of animals that are generally microscopic and aquatic.

Answer to Problem 3STP

Correct answer:

Option (B).

Explanation of Solution

Explanation/justification for the correct answer:

Option (B) inability to live in fresh water. The roundworms are the organism that are parasitic and aquatic, but most of them is not able to live in fresh water. Hence, the correct answer is option (B).

Explanation for incorrect answer:

Option (A) a complete digestive system. The digestive system is complete in the rotifers and nematodes. Hence, it is an incorrect answer.

Option (C) a smaller body size. The rotifers are smaller than nematodes. Hence, it is an incorrect answer.

Option (D) a body surface covered with cilia. The cilia are present in the rotifers not in nematodes. Hence, it is an incorrect answer.