Chapter 28, Problem 18A

Summary Introduction

To write:

The correct term by replacing the italicized word in the given sentence.

Introduction:

Amphibians include frogs, toads, salamanders, newts, and legless caecilians. Most amphibians are distinguished by moist skin without scales, four legs, exchange of gases through skin, a circulatory system with double loop, lungs, and aquatic larvae.

Explanation of Solution

In frogs, food moves from the mouth through the esophagus to the stomach. From the stomach, food moves to the small intestine which receives enzymes from the pancreas to digest food. From the stomach, the food is absorbed into the bloodstream and distributed to the cells of the body. Food passes from the small intestine to the large intestine until the waste material is extracted. At the end of the intestine, there is a chamber named cloaca. Cloaca is a chamber that collects gastrointestinal waste, urinary waste, and eggs or sperm before they leave the body.

Conclusion

Thus, the cloaca is the common chamber and outlet in which the intestinal, urinary and genital tracts are opened in vertebrates. It is present in amphibians, reptiles, birds, elasmobranch, and monotremes.