Estimating population size using quadrats: practical | Exit Quiz | Oak National Academy

Abundance means ...

• how organisms interact with each other in the environment.

• how many different organisms there are in a habitat.

• the number of one species that is found in a habitat.

• how often a quadrat is used in an investigation.

Answer explanation

Abundance is the number of one species that is found within a habitat.

Which of the following is true about quadrats?

• Quadrats should be placed randomly by throwing them.

• 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.

Answer explanation

Quadrats should be placed randomly by randomly selecting coordinates. You should never throw a quadrat. They are used to estimate populations of plants or slow-moving animals throughout the year and give best results when large samples are taken.

What is the area of a quadrat that measures 0.5 m × 0.5 m?

• 1 m²

• 0.5 m²

• 0.25 m²

• 0.1 m²

Answer explanation

A quadrat with 0.5 m sides has an area of 0.5 × 0.5 = 0.25 m²

Look at the results from a quadrat survey of dandelion plants. Calculate the mean number of dandelion plants in each quadrat.

• 78

• 20

• 10

• 7.8

• 0.78

Answer explanation

There were 78 dandelion plants counted in 10 quadrat samples. 78 ÷ 10 gives a mean of 7.8 dandelion plants per quadrat.

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

• 80

• 800

Answer explanation

The field is 40 m² and so 40 × 1 m² quadrats could be placed in the area. 40 × 2 (the mean number of snails) = 80. The estimated snail population is 80 snails.

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.

Answer explanation

The total area of the school field is 100 m². Each quadrat is 1 m² and 10 samples were taken. The area sampled is 10 m². 78 dandelion plants were recorded. The population is (1000 ÷ 10) × 78 = 100 × 78 = 78 000 dandelion plants.