Chapter 4, Problem 9STP

Summary Introduction

Introduction:

In ecology, limiting factors control the various aspects of a population in the environment. Some limiting factors depend on the density of the population while other factors are unrelated to it.

Limiting factors can be described as the factors which affects population growth and may be either density dependent or density -independent.

Answer to Problem 9STP

Correct answer :

The correct answer is option (A). A contagious fatal virus.

Explanation of Solution

Explanation/justification for the correct answer :

Option (A).A contagious fatal virus. Virus and other such fatal contagious pathogen reduces the survival, fitness and reproduction viability in the individuals of the population. These factors affect and reduces the growth of the population. The severity of the contagious virus depends on the population density as the spread of the disease will be more when population density is more. So, the correct answer is Option (A).

Explanation for incorrect answer :

Option (B).Dumping toxic waste in a river. Toxic waste pollutes and harms the ecosystem of the rivers. Due to the toxic waste, the balance of the physical and chemical components are disrupted which in turn affects the biotic or the living component. So, this is an incorrect answer.

Option (C). Heavy rains and flooding. Natural calamities like heavy rains and flooding are environmental factors which do not depend on the density of the population. However, these factors affect the population by reducing food availability, change in physical and chemical components.So, this is an incorrect answer.

Option (D). The environmental catastrophes can strongly affect the population growth. It is independent of the population density but it affects the population by altering the conditions of the environment in which the individual or population grows. So, this is an incorrect answer.