Chapter 24, Problem 2STP

Summary Introduction

Introduction :

Different animals have different features in their feeding process, development of their body, and the features that involve as their support in the body structure. Some of the animals are invertebrates and it includes all the animals that have exoskeletons. The exoskeletons is the outer coverage of the body, it is the tough or hard outer cover, it provides support to the soft tissue of the body, avoid loss of water, and also give protection against predators. The endoskeleton is the internal covering of some of the vertebrates. It includes sea stars and sea urchins; they are made of calcium carbonate, cartilage, etc. Different animals have different body symmetry like asymmetry, radial symmetry, and bilateral symmetry. The animals like sponge have no tissue therefore their body segment is asymmetrical. The body symmetry of animals that are divided equally along the plane means that they have radial symmetry. The animals like birds have bilateral body symmetry.

Answer to Problem 2STP

Correct answer :

The correct answer is option (D) The sea star has radial symmetry and the birds has bilateral symmetry.

Explanation of Solution

Explanation/justification for the correct answer :

Option (D) The sea star has radial symmetry and the birds has bilateral symmetry.The sea star have radial symmetrical body as each part of the arm is identical to the other arm, their body is divided equally along the plane meaning that they have radial symmetry. While the birds have bilateral symmetry as they are divided into mirror image halves in the plane through the central axis.So, the correct answer is option (D).

Explanation for incorrect answer :

Option (A)Both have bilateral symmetry. The birds have bilateral symmetry as they are divided into mirror image halves in the plane through the central axis. The sea star have radial symmetrical body as each part of the arm is identical to the other arm, their body is divided equally along the plan. So, this is an incorrect option.

Option (B) Both have radial symmetry. The sea star have radial symmetrical body as each part of the arm is identical to the other arm, their body is divided equally along the plane. Birds have bilateral symmetry as they are divided into mirror image halves in the plane through the central axis. So, this is an incorrect answer.

Option (C) the sea star has bilateral symmetry and the bird has radial symmetry. The sea star have radial symmetrical body as each part of the arm is identical to the other arm. Their body is divided equally along the plane. The birds have bilateral symmetry, their body is divided into mirror image halves in the plane through the central axis.So, this is an incorrect answer.