Chapter 6, Problem 8STP

Summary Introduction

Introduction :

An important characteristic of any population is its growth rate. The population growth rate explains how fast a given population grows. Some populations tend to remain approximately the same size from year to year. Other populations vary in size depending on conditions within their habitats. To better understand why population grow in different ways, we have to understand two mathematical models for population growth- the exponential growth model and the logistical growth model.

Answer to Problem 8STP

Correct answer :

The correct answer is option (C) a growth rate that increases with time.

Explanation of Solution

Explanation/justification for the correct answer :

Option (C) a growth rate that increases with time. A J-shaped growth curve illustrates exponential growth. Exponential growth or geometric growth occurs when the growth rate is proportional to the size of the population. In an exponential growth, a growth rate increases with time. So, the correct answer is option (C).

Explanation for incorrect answer :

Option (A) the graphical representation goes up and down. In exponential growth, J-shaped growth curve occurs. The exponential growth occurs when the growth rate is proportionate to the size of the population. So, this is an incorrect option.

Option (B) the graphical representation has a flat line. The exponential growth occurs when the growth rate is proportionate to the size of the population. All populations grow exponentially until some limiting factor slows the population’s growth. In the lag phase, the use of available resources is exponential. So, this is an incorrect answer.

Option (D) a growth rate that stays constant in time. In exponential growth, J-shaped growth curve occurs. In the lag phase, the growth rate is slow but after some years the growth occurs proportionally to the size of the population. So, this is an incorrect answer.