# A population of rabbits colonises a new area of grassland. At first the population grows slowly, then very rapidly, before eventually levelling off at a steady size. Describe the changes in birth rate and death rate that account for each of the three phases of population growth shown by this population.

> Cambridge International IGCSE Biology (0610) — 19.4 Populations · Describe · 4 marks

## Mark scheme (4 marks)

1. During the lag (slow growth) phase, birth rate only slightly exceeds death rate / both rates are similar / population numbers increase slowly
2. During the log (rapid/exponential growth) phase, birth rate greatly/significantly exceeds death rate
3. During the stationary phase, birth rate equals death rate / population size remains constant / carrying capacity is reached
4. A limiting factor (e.g. food supply / disease / predation / competition) causes the levelling off / keeps the population at carrying capacity

## Key terms

- [population](https://www.gradenine.co.uk/glossary/population)
- [birth rate](https://www.gradenine.co.uk/glossary/birth-rate)
- [death rate](https://www.gradenine.co.uk/glossary/death-rate)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-population-of-rabbits-colonises-a-15c1447e) · Published by Druglandscape Ltd.