69. Among the following which is not an density dependent factor effecting population
    (1) Competition (2) Food
    (3) Temperature (4) Nutrients

Introduction

Population sizes in ecosystems are regulated by a mix of density-dependent and density-independent factors. Knowing which factors fall into each category is essential for understanding how populations grow, stabilize, or decline. Let’s clarify which of the given factors—competition, food, temperature, or nutrients—is not density dependent.

What Are Density-Dependent Factors?

Density-dependent factors are those whose effects intensify as population density increases. They are typically biotic (related to living organisms) and act as natural checks on population growth. As the number of individuals rises, these factors become more influential, helping to stabilize population size.

Common density-dependent factors include:

• Competition: More individuals mean greater competition for limited resources like food, water, and space.

• Food: Scarcity of food becomes more pronounced as population density increases, leading to increased mortality or reduced reproduction.

• Nutrients: Like food, nutrients become limiting as population density rises, increasing competition and impacting growth and survival.

What Are Density-Independent Factors?

Density-independent factors affect populations regardless of their density. These are usually abiotic (non-living) and include things like:

• Temperature

• Natural disasters (floods, fires, hurricanes)

• Weather events

These factors can cause sudden changes in population size but do not become more or less intense as the population grows or shrinks.

Which Factor Is Not Density Dependent?

Let’s review the options:

1. Competition – Density dependent: More individuals lead to more competition.

2. Food – Density dependent: Scarcity increases with population size.

3. Temperature – Not density dependent: Affects all individuals equally, regardless of population density.

4. Nutrients – Density dependent: More individuals increase competition for nutrients.

Conclusion

Temperature is not a density-dependent factor affecting population size. Unlike competition, food, and nutrients—which become more limiting as populations grow—temperature impacts populations regardless of how many individuals are present.

Correct answer: (3) Temperature