SSC Selection Post 2025 PYQ — Question 18

Correct Answer: Carrying capacity

Explanation

The maximum population size of a biological species that a specific environment can sustain indefinitely, given the available food, water, habitat, and other necessities, is known as its Carrying Capacity. In ecology and environmental science, it is typically represented by the constant symbol $K$.

When a population is small, it often experiences rapid growth because resources are abundant. However, as the population size approaches the carrying capacity, resources become limited, leading to increased competition. This slows down the growth rate until the population levels off and stabilizes around the environment's maximum limit. If a population exceeds its carrying capacity, it results in resource depletion and environmental degradation, causing a subsequent population crash or decline until balance is restored.

Key Points

Population density refers to the number of individuals living per unit of geographic area (such as per square kilometer), describing how crowded a place is rather than its resource limit.

Fertility rate measures the average number of children born to a woman during her lifetime within a specific population, acting as a driver of population growth.

Dependency ratio is an economic indicator that compares the proportion of the population that is not in the labor force (children and senior citizens) to those who are typically working.

Important Questions and Answers

Question: Which type of population growth curve graphically illustrates a population leveling off at its carrying capacity?

Answer: A logistic growth curve (S-shaped curve) depicts a population stabilizing as it encounters the carrying capacity of its environment.

Question: What happens to the mortality rate of a species if its population significantly overshoots the carrying capacity?

Answer: The mortality rate increases sharply due to severe starvation, diseases, and intense competition for remaining depleted resources.