What is a population?

all the organisms of one species in an area. It is a single species in one place at one time.

Which does not limit the growth of a population?

an unlimited food supply. With plenty of food and nothing else limiting it, a population keeps growing.

What shape is a typical population growth curve?

S-shaped (sigmoid). It rises slowly, then quickly, then levels off.

In which phase does the population grow fastest?

exponential phase. Births greatly outnumber deaths.

What is true in the stationary phase?

The birth rate equals the death rate. The numbers stay roughly steady.

Populations · Cambridge IGCSE Biology 0610 revision

In plain words

Put a few rabbits on an island with plenty of grass and their numbers will rocket, for a while. Then the grass runs short, disease spreads, and the numbers level off. Every population is held in check by something.

Three things to know

A population is all the organisms of one species living in one area at the same time. A community is all the populations of different species in an ecosystem. An ecosystem is a community together with its environment.
A population's growth is limited by food supply, competition, predation and disease.
A new population grows in an S-shaped (sigmoid) curve: a slow start (lag phase), fast growth (exponential phase), levelling off (stationary phase) and, if resources run out, a fall (death phase).

Tips and tricks

Population: one species. Community: all the species. Ecosystem: the community plus its surroundings.
Match each part of the curve to a reason: births above deaths in the exponential phase; births equal to deaths in the stationary phase.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Populations: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

What is a population?
- all the living things in an area
- all the organisms of one species in an area (the answer)
- one organism
- all the plants in an area
It is a single species in one place at one time.
Which does not limit the growth of a population?
- shortage of food
- disease
- predators
- an unlimited food supply (the answer)
With plenty of food and nothing else limiting it, a population keeps growing.
What shape is a typical population growth curve?
- a straight line
- S-shaped (sigmoid) (the answer)
- a circle
- V-shaped
It rises slowly, then quickly, then levels off.
In which phase does the population grow fastest?
- lag phase
- exponential phase (the answer)
- stationary phase
- death phase
Births greatly outnumber deaths.
What is true in the stationary phase?
- No organisms die.
- The birth rate equals the death rate. (the answer)
- No organisms are born.
- The population doubles.
The numbers stay roughly steady.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 9 marks. Write your answers on paper, then check them.

Populations

Cambridge IGCSE Biology 0610 · 9 marks · papermunch.org

Name ______________________________ Date ______________

State what is meant by a population, a community and an ecosystem.[3]
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A population is a group of organisms of one species living in the same area at the same time. A community is all the populations of different species in an ecosystem. An ecosystem is a community of organisms interacting with their environment.
I got this one
State three factors that limit the growth of a population.[3]
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Any three: food supply, competition, predation, disease.
I got this one
Describe and explain the stationary phase of a population growth curve.[3]
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The population stays about the same size. The birth rate equals the death rate, because a factor such as food supply, space or disease is limiting growth.
I got this one

Answers: Populations

1. A population is a group of organisms of one species living in the same area at the same time. A community is all the populations of different species in an ecosystem. An ecosystem is a community of organisms interacting with their environment.
2. Any three: food supply, competition, predation, disease.
3. The population stays about the same size. The birth rate equals the death rate, because a factor such as food supply, space or disease is limiting growth.