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Year 9 Science Biological Sciences AC9S9U01

Population Ecology

Population ecology studies how populations of organisms change over time and the factors that regulate population size. Key concepts include carrying capacity, limiting factors, and predator-prey dynamics.

What You Need to Know

Key Concept Diagram

Carrying capacity (K) is the maximum population size an environment can sustain

Limiting factors: food, water, space, disease, and predation restrict population growth

Exponential growth occurs when resources are unlimited; logistic growth levels off at carrying capacity

Predator-prey cycles: prey increase leads to predator increase, then prey decline, then predator decline

Key Vocabulary

Carrying capacity

The maximum population size an ecosystem can support sustainably

Limiting factor

An environmental resource or condition that restricts population growth

Exponential growth

Population growth at an accelerating rate when resources are unlimited

Logistic growth

Population growth that slows as it approaches carrying capacity

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

A population graph that grows rapidly then levels off at a stable size shows:

Question 2

In a predator-prey system, when the prey population dramatically increases, what typically happens next?

Question 3

Which is an example of a density-dependent limiting factor?

Key Concepts Summary