New
New
Year 10
AQA
Higher

Measuring the size and distribution of populations of organisms

I can describe how to identify species, estimate the population size of a species and how to investigate the effect of a factor on the distribution of this species.

New
New
Year 10
AQA
Higher

Measuring the size and distribution of populations of organisms

I can describe how to identify species, estimate the population size of a species and how to investigate the effect of a factor on the distribution of this species.

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Lesson details

Key learning points

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

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.

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.

There are many opportunities to carry out sampling methods outside the classroom, including using sweep nets and pond dipping in your local context. Mark-release-recapture activities can be undertaken using pitfall traps. The additional materials sheet may be needed to support the task.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
What do we call a survey of plants and/or animals which provides information about the populations of organisms?
Correct Answer: sampling, a sample, sample
Q2.
Light intensity is an example of ...
a biotic factor
Correct answer: an abiotic factor
a factor that is both biotic and abiotic
Q3.
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
Correct answer: pooter
Q4.
What piece of equipment might be used to sample plants and slow-moving animals?
pooter
Correct answer: quadrat
pitfall trap
nets
Q5.
Match the following words with their definitions.
Correct Answer:adaptation,a feature that helps an organism to survive in a habitat

a feature that helps an organism to survive in a habitat

Correct Answer:bias,when the person carrying out an investigation affects the outcome

when the person carrying out an investigation affects the outcome

Correct Answer:biodiversity,the range of different living organisms (species) that live in a place

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

Correct Answer:biomass,the mass of living material in one or more organisms

the mass of living material in one or more organisms

Q6.
A habitat provides organisms with food, shelter and a place to live. Which of the following might be the habitat of a robin?
An image in a quiz
a rock pool
Correct answer: a garden
a compost heap
a wildflower meadow

6 Questions

Q1.
What means to give an approximate value, for example, when sampling the population of fish in a lake?
Correct Answer: estimate, an estimate, estimation, estimating
Q2.
What is the image an example of?
An image in a quiz
a pyramid of numbers
a pyramid of biomass
Correct answer: a classification key
a food web
Q3.
The image shows a sample of organisms found from a pond. Why has the net been emptied into a white tray which contains water?
An image in a quiz
The white tray helps the organisms to see each other.
Correct answer: It helps you to be able to identify organisms as the white makes them stand out.
Correct answer: 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.
Q4.
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.
Correct answer: Mark the organisms with a mark that means the organism doesn't stand out.
Capture more organisms as soon as marked individuals are released.
Q5.
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
Correct answer: 200
2000
Q6.
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
Correct answer: 90
145

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