Chapter 30.1, Problem 4MI

Summary Introduction

To define:

The given term “retain”to show its scientific meaning.

Introduction: In addition to having hair and mammary glands, mammals have other characteristics such as a high metabolic rate, specialized teeth and digestive systems, a diaphragm, a four chambered heart and a highly developed brain.

Answer to Problem 4MI

Retain means to keep possession of something or to continue to hold something.

Explanation of Solution

The kidneys of mammals excrete metabolic wastes and maintain the homeostatic balance of body fluids. Kidneys filter urea from the blood. Urea is the end product of cellular metabolism. The kidneys either excrete or retain sufficient amount of water in body fluids as well. This means kidneys can absorb and continue to hold some amount of water in body fluids. As kidneys can control the amount of water in body fluids and cells, mammals can survive in extreme conditions like deserts where there is scarcity of water.