Chapter 29, Problem 6STP

Summary Introduction

Introduction:

Reptiles are fully adapted to life on land and were the first completely terrestrial vertebrates. The characteristics that allow reptiles to succeed on land include a shelled egg, scaly skin, and more efficient circulatory and respiratory systems.

Answer to Problem 6STP

Correct answer:

The correct answer is option (C) 4.

Explanation of Solution

Explanation/justification for the correct answer:

Option (C) 4. The option 4 represents leathery shell. The leathery shell is the fluid-filled membrane. The leathery shell of amniotic egg can protect the internal fluids and embryo, and keep it from drying out during development. So, the correct answer is option (C).

Explanation for incorrect answer:

Option (A) 1. The option 1 represents amnion. An amnion is a membrane that surrounds a developing embryo. It is filled with fluid that protects the embryo during development. So, this is an incorrect option.

Option (B) 2. The option 2 represents yolk sac. The yolk sac is a membranous sac attached to the embryo, produced by the hypoblasting cells adjacent to the embryonic disc. So, this is an incorrect option.

Option (D) 5. The option 5 represents chorion. The chorion is the outermost membrane of the egg that allows oxygen to enter and keeps fluid inside the egg. So, this is not the correct option.