Problem 5 - Biology: The Dynamic Science

Question

According to the logistic model of population growth, the absolute number of individuals by which a population grows during a given time period: a. gets steadily larger as the population size increases. b. gets steadily smaller as the population size increases. c. remains constant as the population size increases. d. is highest when the population is at an intermediate size. e. fluctuates on a regular cycle.

Step-by-Step Solution

Answer

The correct answer is option d. In a logistic growth model, population growth rate is highest when the population is at an intermediate size.

Step 1: Understanding Logistic Growth Model

In ecological terms, the Logistic Growth Model is applied when the resources are limited, thus restricting the uncontrolled growth of the population. At initial stages, when population is small, it follows an exponential growth. However, as population increases, competition for resources intensifies thereby slowing down the growth. This continues until the growth stops and the population reaches its carrying capacity.

Step 2: Analyzing the Options

Given this information about the logistic model, we now look at each of the given options and apply our understanding of the logistic model to find which one fits.

Step 3: Evaluation

Options a, b and c are excluded as in the logistic growth model, the number of individuals by which a population grows does not steadily increase or decrease, nor does it remain constant. Option e is also excluded because, although the population size may fluctuate slightly due to factors such as disease or famine, it generally does not fluctuate on a regular cycle according to this model. Option d correctly states that population growth rate is highest when the population size is at an intermediate level. This is the point at which growth begins to slow due to resources becoming increasingly scarce, but has not yet reached the plateau of the carrying capacity.