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Edexcel IGCSE Biology organisms in the environment

Use organism-environment evidence to define ecology terms, sample populations fairly and compare biodiversity from field measurements.

Syllabus
First assessment 2019
Course
Biology 4BI1

Exam points

  • Define population, community, habitat and ecosystem from species, area and environment wording.
  • Explain quadrat sampling choices using random coordinates, repeats and controlled variables.
  • Interpret field tables to compare biodiversity, distribution and population size per m2.

Covered syllabus points

4.1 Ecology terms4.2 Comparing population size4.3B Biodiversity4.4B Quadrat sampling practical4.5 Abiotic and biotic factors

(a) The organism in the environment question 1

[Maximum number: 1]

The diagram shows part of a woodland food web.

Figure for Question (a) The organism in the environment question 1 — Edexcel IGCSE Biology

Which of these describes the woodland community?

A

all the abiotic and biotic factors in the area

B

all the blackbirds in the area

C

all the different species and the habitat

D

all the different species in the area

(a) The organism in the environment question 2

[Maximum number: 5]

Limpets are marine animals that attach to rocks on coastal shores.

The diagram shows a food web that contains limpets.

Figure for Question (a) The organism in the environment question 2 — Edexcel IGCSE Biology

Question (a)

(a)

State what is meant by the term population.

[ 1 ]

Question (b)

(b)

Some scientists think that food webs on rocky shores are at risk from an increase in greenhouse gases.

The scientists record these two factors during August every year for 17 years.
- the number of limpets per m2m^{2} on a rocky shore
- the mean temperature at the same rocky shore

The graph shows the scientists' results.

Figure for Question (b) — Edexcel IGCSE Biology
[ 4 ]

Question (i)

(i)

Describe how the scientists could determine the number of limpets on the rocky shore.

[ 3 ]

Question (ii)

(ii)

Give one factor the scientists should control when comparing the number of limpets per m2m^{2} each year.

[ 1 ]

(a) The organism in the environment question 3

[Maximum number: 13]

A group of students investigate the biodiversity in two fields, A and B.
Field A is grazed by cattle and field B has no cattle.

Question (a)

(a)

Explain what is meant by the term biodiversity.

[ 2 ]

Question (b)

(b)

The students investigate the plant species in each field.

They counted the number of each species in five 0.5 m×0.5 m0.5 \mathrm{~m} \times 0.5 \mathrm{~m} quadrats.
They repeated this for each field.
Table 1 shows their results.

Table 1

Table 1

[ 11 ]

Question (i)

(i)

Describe how the quadrats should be placed to obtain unbiased species numbers for each field.

[ 2 ]

Question (ii)

(ii)

For the most frequently occurring plant species in field B, calculate the number of plants in one square metre.
number of plants =……

[ 3 ]

Question (iii)

(iii)

Name the species with the greatest variation in number of plants recorded in quadrats for field B.

Table 1 is repeated here.

Table 1

Table 1

[ 1 ]

Question (iv)

(iv)

The students conclude that grazing affects the species in field A .

Using information in Table 1 and your own knowledge, discuss the students' conclusion.

[ 5 ]
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