Flows of Energy & Matter (DP IB Environmental Systems & Societies (ESS): SL)

Exam Questions

53 mins10 questions
1a1 mark

State the units used for net primary productivity.

1b1 mark

State the formula for calculating net primary productivity.

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22 marks

Outline the meaning of the term gross secondary productivity.

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32 marks

Define maximum sustainable yield.

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4a2 marks

State two storages in the carbon cycle.

4b2 marks

State two flows in the carbon cycle.

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1a5 marks

Part of the carbon cycle is shown in the diagram below.

screenshot-2023-07-26-at-10-21-43

i)

Identify processes X and Y in the diagram.

[2]

ii)

Describe how carbon is released during process Y.

[3]

1b4 marks

Carbon from fossil fuels enters the atmosphere during combustion.

i)

Explain how this process contributes to rising average global temperatures.

[2]

ii)

Cutting down trees during deforestation increases the problem described in part i). Explain how.

[2]

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2a5 marks

Describe the role of bacteria in the nitrogen cycle.

2b2 marks

The figure below shows a diagram of a stream that runs past a farm. A group of students took water samples at various locations along the stream and measured the nitrate concentration in parts per million (ppm) in those water samples. The students have marked these nitrate concentrations on their diagram.

screenshot-2023-07-26-at-11-03-38

Explain how the farm may be causing the increase in nitrate concentration in the water.

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3a2 marks

Define the term gross primary productivity.

3b4 marks

Only around 1% of the light energy that reaches the Earth’s atmosphere is captured by plants and made available to other organisms in the food chain.

Suggest reasons for this low value.

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4a
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3 marks

Woodlice are detritivorous insects (they feed on the dead remains of plants). A biologist estimated the numbers of woodlice at two different sites in a woodland ecosystem. They also estimated the net primary production of the sites to see if this influenced the numbers of woodlice present. Their results are shown in the table below.

Site

Number of woodlice per m2

Net primary productivity / g m-2 y-1

X

240

1 320

Y

80

460

Although net primary production is a measure of plant biomass formed per year, it does not represent the total amount of plant biomass formed per year by photosynthesis.

i)

Explain why.

[1]

ii)

Explain why there is a greater number of woodlice in site X than site Y.

[1]

This woodland ecosystem has a total average gross primary productivity of 20 000 kJ m-2 y-1 but the net primary productivity is calculated to be 12 000 kJ m-2 y-1.

iii)

Calculate how much energy one square metre of this grass loses as heat from respiration in one year.

[1]

4b2 marks

The figure below shows the energy transfers taking place in a simple food chain. The energy values are all given in kJ m-3 y-1.

screenshot-2023-07-26-at-12-36-51

The efficiency of energy transfer can be calculated using the following equation:

Ecological efficiency = (energy used for new biomass ÷ energy supplied) × 100

Use information in the figure and the equation provided to calculate the efficiency of energy transfer for zooplankton.

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17 marks

Compare and contrast the concepts of sustainable development and sustainable yield.

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29 marks

Discuss how human activities affect the nitrogen cycle and the impacts of this on ecosystems.

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