The graph below shows the birth rate and the death rate of a mouse population over a
three-year period. The immigration rate and the emigration rate of the population are equal.
Birth and Death Rates
Birth Rate and Death Rate
of a Mouse Population
Year 1
Year 2
Time
Birth rate
Key
Year 3
Death rate
a. Describe what happens to the size of the population for each year shown on the graph.
Explain your answers.
b. Identify three factors that could affect the death rate of the mouse population, and explain
why each factor affects the death rate.