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Populations and Communities

Population dynamics and changes in population size

  • 3 things to know
  • Unit A2 1

Overview

Four processes that determine the size of a population, how these four processes combine to change a population and density-dependent and density-independent factors.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Process

Name the four processes that determine the size of a population.

Key term

What is immigration?

Key term

What is emigration?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Name the four processes that determine the size of a population.

    Model answer

    Population size is determined by birth, death, immigration and emigration.

  2. 2

    What is immigration?

    Model answer

    Immigration is the movement of individuals of a species into a population from elsewhere.

  3. 3

    What is emigration?

    Model answer

    Emigration is the movement of individuals of a species out of a population to live elsewhere.

  4. 4

    Give two abiotic factors that make a population change with the seasons.

    Model answer

    Temperature and day length change with the seasons and affect both breeding and survival.

  5. 5

    Give one biotic factor that makes a population change with the seasons.

    Model answer

    The seasonal availability of food alters the birth and death rates of the animals that depend on it.

  6. 6

    Why does the population of many insects peak in summer?

    Model answer

    Warmth speeds their development and their food plants are abundant, so the birth rate rises steeply while the death rate stays low.

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