Organisation of an Ecosystem Practice Questions

Question 1

4 marks

A moorland community contains the following feeding relationships.

heather → heather beetle → meadow pipit → merlin
grass → field vole → merlin
grass → field vole → stoat

(a)

Name the two producers in this food web.

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(b)

Name one primary consumer in this food web.

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(c)

The merlin is a predator. Name one organism in the food web that is prey for the merlin.

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(d)

Name one organism in this food web that is both a predator and prey.

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Question 2

4 marks

Water is continuously recycled between the sea, the atmosphere and the land.

(a)

Name the process by which liquid water from the surface of the sea becomes water vapour in the air.

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(b)

The water vapour rises and cools to form clouds. Name this process.

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(c)

Name the process by which plants release water vapour from their leaves into the air.

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(d)

Give one reason why the water cycle is important for organisms living on land.

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Question 3

4 marks

A student used a $0.5\ \text{m} \times 0.5\ \text{m}$ quadrat to count the number of dandelion plants at 10 random positions on a lawn.

Table 1 shows the results.

Quadrat	1	2	3	4	5	6	7	8	9	10
Number of dandelion plants	3	5	2	5	7	4	5	6	3	0

(a)

Calculate the mean number of dandelion plants per quadrat.

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(b)

Give the mode of the results in Table 1.

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(c)

Determine the median of the results in Table 1.

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Question 4

4 marks

A gardener puts grass cuttings, dead leaves and vegetable peelings into a compost heap. After several months the material has decayed into compost, which she digs into her flower beds.

(a)

Explain how adding compost to the soil helps her flowers to grow.

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(b)

In dry weather the gardener waters the compost heap. Give one reason why this increases the rate of decay.

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(c)

The gardener also turns the heap over with a fork to mix air into it. Give one reason why this increases the rate of decay.

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Question 0

6 marks

A footpath crosses a playing field. Students noticed that there seemed to be more daisy plants far away from the footpath than close to it.

(a)

Describe how the students could use a transect and quadrats to investigate how the number of daisy plants changes with distance from the footpath.

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(b)

The students want to present their results as a graph. Name the type of graph they should draw and state which variable should be plotted on each axis.

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Question 0

6 marks

A field is a rectangle measuring $40\ \text{m}$ by $25\ \text{m}$ .

A scientist used a quadrat of side $0.5\ \text{m}$ to estimate the number of plantain plants in the field. Table 1 shows her results.

Quadrat	1	2	3	4	5	6	7	8	9	10
Number of plantain plants	5	8	4	7	6	10	3	5	6	6

(a)

Describe how the scientist should place the quadrats so that the sampling is random.

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(b)

Use the data in Table 1 to calculate an estimate of the total number of plantain plants in the field.

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(c)

Give one reason why the scientist's answer to part (b) is only an estimate.

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Question 0

5 marks

Snowshoe hares are eaten by lynx. Table 2 shows estimates of the numbers of snowshoe hares and lynx in a large area of forest over 8 years.

Year	1	2	3	4	5	6	7	8
Number of hares (thousands)	10	30	60	40	15	8	20	45
Number of lynx (hundreds)	2	3	6	9	7	4	2	4

(a)

Give the year in which the hare population was at its highest.

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(b)

The lynx population reached its highest number one year after the hare population reached its highest number. Explain why.

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(c)

Explain why the hare population fell from 60 000 in year 3 to 8000 in year 6.

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Question 0

5 marks

Figure 1 shows part of the carbon cycle.

(a)

Name the process labelled A in Figure 1.

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(b)

Name the process labelled B in Figure 1.

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(c)

Process C is carried out by microorganisms in the soil.

Explain the importance of these microorganisms in an ecosystem.

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Question 0

6 marks

A student investigated the effect of temperature on the rate of decay of fresh milk.

She put $20\ \text{cm}^3$ of fresh milk into each of two sealed tubes. One tube was kept at $4\ ^\circ\text{C}$ and the other at $20\ ^\circ\text{C}$ . She measured the pH of the milk in each tube at the start and again after 6 days.

Table 3 shows her results.

Temperature / $^\circ$ C	pH at start	pH after 6 days
4	6.8	6.5
20	6.8	4.4

(a)

Calculate the mean rate of change of pH per day for the milk kept at $20\ ^\circ\text{C}$ .

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(b)

Explain why the pH of the milk kept at $4\ ^\circ\text{C}$ changed much more slowly.

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(c)

The student tested only one tube of milk at each temperature.

Explain how she could improve her method to increase confidence in her results.

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Question 0

7 marks

A butterfly species has been recorded in Britain for many years. Scientists count the number of $10\ \text{km}$ squares in which the species is found.

Table 4 shows the results for 1980 and 2020.

Region	Number of $10\ \text{km}$ squares in 1980	Number of $10\ \text{km}$ squares in 2020
Northern Britain	250	410
Southern Britain	800	620

The mean summer temperature in Britain rose by $1.1\ ^\circ\text{C}$ between 1980 and 2020. The caterpillars of this butterfly feed on only one species of grass, which dies back when the soil becomes dry.

(a)

Calculate the percentage increase in the number of $10\ \text{km}$ squares in northern Britain between 1980 and 2020.

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(b)

Suggest how the rise in temperature could explain the changes in the distribution of this butterfly shown in Table 4.

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(c)

Explain why the data in Table 4 do not prove that the rise in temperature caused the changes in distribution.

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Question 0

6 marks

A farmer feeds animal waste and vegetable waste into a biogas generator. The generator produces methane, which the farmer burns to heat his farmhouse.

(a)

The conditions inside a biogas generator are different from the conditions in a compost heap.

Describe one difference and explain why it is needed.

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(b)

The generator produces much less methane per day in winter than in summer.

Explain why, and suggest how the farmer could increase the amount of methane produced in winter.

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Question 0

6 marks

A lake contains a community of organisms. One food chain in the lake is:

algae → zooplankton → small fish → pike

(a)

Explain why all food chains must begin with a photosynthetic organism such as the algae.

/ 3

(b)

A chemical spill kills most of the algae in the lake.

Suggest and explain the effect this has on the numbers of zooplankton and of pike in the lake.

/ 3

Cell Biology

Organisation

Infection & Response

Bioenergetics

Homeostasis & Response

Inheritance, Variation & Evolution

Ecology

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