New
New
Year 10
OCR
Foundation

Estimating population size using quadrats: practical

I can use quadrats to estimate the population size of a species.

New
New
Year 10
OCR
Foundation

Estimating population size using quadrats: practical

I can use quadrats to estimate the population size of a species.

Lesson details

Key learning points

  1. Quadrats can be used to sample an area to estimate population size (abundance).
  2. Quadrats are used to sample plants and slow-moving, small animals.
  3. Quadrats can be placed at random to help avoid bias.
  4. Using quadrats to estimate population size (species abundance) in an area.
  5. Using quadrats to investigate the population size of a plant species using random sampling.

Common misconception

Quadrats can be used to give an accurate picture of a habitat or ecosystem.

Sampling using a quadrat provides only a snapshot of a specific area at a specific time. To give an accurate picture, quadrat samples need to be taken over a long period of time to provide a more complete picture of a habitat or ecosystem.

Keywords

  • Population - A group of organisms of the same type, in the same place, is called a population.

  • Sampling - Sampling is a survey of plants and/or animals which provides information about the populations of organisms.

  • Quadrat - A quadrat is a square frame which is used to sample populations of plants or slow-moving animals.

  • Abundance - Abundance is the number of organisms of a species found within a habitat.

Having carried out an investigation and calculated an estimated population size, pupils studying the same species can pool data, calculate the estimated population from a larger data set and discuss the reasons for any differences in their results.
Teacher tip

Equipment

Quadrat, two 20 m tape measures, clipboard, pencils, bag of numbers for random coordinate generation.

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision required

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.
True or false? A bottle garden is an example of an ecosystem.
An image in a quiz
Correct answer: true
false
Q2.
What is this piece of equipment called?
An image in a quiz
Correct Answer: quadrat, A quadrat
Q3.
Which of the following populations of organisms might you use a quadrat to sample?
Correct answer: dandelion plants
wasps
Correct answer: starfish
blackbirds
Q4.
The diagram shows a pitfall trap. Which of the following organisms might be sampled using this piece of equipment?
An image in a quiz
Correct answer: beetles
bees
pigs
daisy plants
Q5.
Rainfall in a habitat is an example of ...
both a biotic and an abiotic factor.
a biotic factor.
Correct answer: an abiotic factor.
Q6.
When carrying out a mark-release-recapture experiment we put a small mark on the organism so that we know it has been captured before. What is important to remember when marking an organism?
To make sure that the mark stands out so it is easy to count.
Correct answer: To use a substance that is harmless to the organism.
To make sure that the mark is large.
To make the organism stand out to a predator.

6 Questions

Q1.
Abundance means ...
how organisms interact with each other in the environment.
how many different organisms there are in a habitat.
Correct answer: the number of one species that is found in a habitat.
how often a quadrat is used in an investigation.
Q2.
Which of the following is true about quadrats?
Quadrats should be placed randomly by throwing them.
Correct answer: More reliable results are given by taking a large sample.
Quadrats should only be used in the summer when plants are flowering.
Quadrats are useful to sample populations of mice.
Q3.
What is the area of a quadrat that measures 0.5 m × 0.5 m?
1 m²
0.5 m²
Correct answer: 0.25 m²
0.1 m²
Q4.
Look at the results from a quadrat survey of dandelion plants. Calculate the mean number of dandelion plants in each quadrat.
An image in a quiz
78
20
10
Correct answer: 7.8
0.78
Q5.
Ten 1 m² quadrats were placed in a 40 m² field. A mean of 2 snails were found in every quadrat. Estimate the population size of the whole field.
8
40
Correct answer: 80
800
Q6.
The results from a quadrat survey of dandelion plants in a school field is shown. Each quadrat is 1 m². If the school field is 1000 m², estimate the total population size of dandelion plants.
An image in a quiz
Correct Answer: 78 000, 78000 dandelion plants, 78 000 dandelions, 78000, 78 000 dandelion plants

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