Chapter 29, Problem 7A

Summary Introduction

Introduction:

Reptiles were the first completely terrestrial vertebrates and are fully adapted to live on land. Characteristics like scaly skin, circulatory and respiratory system and shelled egg allow them to succeed on land. They have common characteristics with other organisms such as the presence of an amnion and other membranes.

Answer to Problem 7A

Correct answer:

The correct answer is option (B) the cloaca

Explanation of Solution

Explanation/justification for the correct answer:

Option (B) the cloaca is a chamber that collects gastrointestinal waste, urinary waste, and eggs or sperm before they leave the body. It is the opening into which the urinary, intestinal and genital tracts open. When urine enters the cloaca, water is reabsorbed to form uric acid, which is a semi solid excretion. Thus, the correct answer is option (B).

Explanation for incorrect answer:

Option (A) the lungs. Most of the reptiles, except for some aquatic turtles use lungs for exchange of gas. So, this is an incorrect option.

Option (C) the heart. Most reptiles have a three chambered heart which has two separate atria and one ventricle that is partially divided by a septum. The right atrium receives deoxygenated blood returning from the body tissues. It transfers this blood into the ventricle from where it is pumped into the lungs for oxygenation. The oxygenated blood from the lungs returns to the left atrium and again goes into the same ventricle from where it is pumped into the tissues of the body. So, this is an incorrect answer.

Option (D) the stomach. The stomach is responsible for storing food during digestion. It contains hydrochloric acid, which not only aids in the breakdown of the food, but also kills live prey. Hydrochloric acid can also help decalcify bony material. So, this is an incorrect answer.