New
New
Year 10
Edexcel
Foundation

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
Edexcel
Foundation

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.

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.

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.

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).

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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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