What factor commonly slows population growth in an ecosystem?

• A. Limited resources such as food, water, or habitat.
• B. Unlimited resources.
• C. No competition.
• D. Infinite energy input.

Answer: (A)

Limiting resources slow population growth because they cap how many individuals the environment can support. When a population grows, demand for food, water, and space increases. If these resources become scarce, not enough offspring survive and some individuals die, or organisms invest less in reproduction. The result is a slower growth rate and a leveling off as the population nears the environment’s carrying capacity.

This idea fits real-world patterns like a lake fish population that grows quickly when algae is abundant but slows as the algae stock declines, or a plant-insect system where limited plant matter keeps insect numbers from increasing indefinitely.

Unlimited resources would remove these constraints, allowing continued rapid growth. No competition would mean resources aren’t being fought over, which also reduces slowing. Infinite energy input isn’t realistic in nature and would effectively imply unlimited resources as well. So the factor that commonly slows growth is the limitation of resources such as food, water, or habitat.