Biology 5090 · O Level · Ecosystems and biodiversity

Ecosystems and biodiversity — practice question

A student studied how many plants were growing on a school field. This was carried out by looking at small parts of the field with a square frame that measured 0.5 m \times 0.5 m. Fig. 2.1 displays the plants in one of these 0.5 m \times 0.5 m samples.
(a)[1]

There were three different plant species in the sample. The student counted how many plants of each of these species were present in this sample. One plant did not lie completely inside the square frame. Suggest and explain what you would do with this plant.

(b)[1]

Count how many plants of species E are shown in Fig. 2.1, taking your answer to (a) into account. Write your answer in Table 2.1.

(c)[2]

The full field measured 10\,\text{m} \times 20\,\text{m}. Use the sample in Fig. 2.1 to estimate the number of plants of species E in the entire field and record this value in Table 2.1. Show your working.

(d)[1]

Explain why the student counted the numbers of plants in samples of the field instead of counting the number of plants in the whole field.

(e)[2]

Suggest two reasons why using several samples would make the estimate for the number of plants in the whole field more accurate.

(f)[4]

Use the data in Table 2.1 to draw a bar chart showing the estimated number of plants of species C, D and E in the whole field.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Include: more than half is in the square so a half individual cannot be counted; OR Exclude: it is not fully in the square so a half individual cannot be counted

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