Measuring the size and distribution of populations of organisms | Combined science

Starter quiz

What do we call a survey of plants and/or animals which provides information about the populations of organisms?

'sampling' ✓
Light intensity is an example of ...

a biotic factor

an abiotic factor ✓

a factor that is both biotic and abiotic
Which of the following pieces of apparatus would be useful to sample small organisms on the leaves of a tree?

quadrat

kick net

pitfall trap

pooter ✓
What piece of equipment might be used to sample plants and slow-moving animals?

pooter

quadrat ✓

pitfall trap

nets
Match the following words with their definitions.

adaptation

⇔

a feature that helps an organism to survive in a habitat ✓

bias

⇔

when the person carrying out an investigation affects the outcome ✓

biodiversity

⇔

the range of different living organisms (species) that live in a place ✓

biomass

⇔

the mass of living material in one or more organisms ✓
A habitat provides organisms with food, shelter and a place to live. Which of the following might be the habitat of a robin?

a rock pool

a garden ✓

a compost heap

a wildflower meadow

Exit quiz

What means to give an approximate value, for example, when sampling the population of fish in a lake?

'estimate' ✓
What is the image an example of?

a pyramid of numbers

a pyramid of biomass

a classification key ✓

a food web
The image shows a sample of organisms found from a pond. Why has the net been emptied into a white tray which contains water?

The white tray helps the organisms to see each other.

It helps you to be able to identify organisms as the white makes them stand out. ✓

The water makes sure that they stay alive after being caught. ✓

The white tray helps to create an environment that is similar to the habitat.
When carrying out a mark-release-recapture experiment what do you need to remember to do?

Mark the organisms with something that is harmful.

Mark the organisms with a bright mark so you can see them.

Mark the organisms with a mark that means the organism doesn't stand out. ✓

Capture more organisms as soon as marked individuals are released.
100 beetles were caught and marked in a mark-release-recapture experiment. Two days later in a second catch 80 beetles were caught. 40 of these were marked. What is the population of beetles?

2

20

200 ✓

2000
30 woodlice were caught and marked in a mark-release-recapture experiment. Two days later in a second, 15 woodlice were caught. 5 of these were marked. What is the population of woodlice?

300

45

90 ✓

145

Worksheet

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Lesson Details

Key learning points

Keys can be used to identify organisms in their habitat.
It is not possible to count all the organisms in a population, so we use sampling to estimate population size.
Sampling organisms in habitats (e.g. a river using kick sampling and a net).
Sampling animals using a pooter.
Estimating populations using capture-mark-recapture.

Common misconception

Many pupils believe that in order to determine a population size within a habitat, all organisms within a habitat have to be counted.

Populations can be estimated using sampling techniques. As long as a sample size is large enough, it will provide a reliable estimate of the population size. Pupils should understand that counting all individuals in a habitat is very difficult to do.

Keywords

Classification key - A classification key is a series of questions about the features of organisms that help us to classify them correctly.
Population - A group of organisms of the same type in the same place is called a population.
Estimate - Estimate means to give an approximate value, for example, you can estimate the population of fish in a lake by sampling.
Sampling - Sampling is a survey of plants and/or animals which provides information about the populations of organisms.