Human Influences on the Environment (Edexcel IGCSE Biology)

Exam Questions

2 hours13 questions
1a
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1 mark

Which row of the table gives the combination of factors that would lead to an increased amount of human waste being produced?

+ means increasing       - means decreasing

 

Standard of Living

Population 

Life expectancy

A

+

+

+

B

-

+

+

C

-

-

+

D

-

-

-

1b
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2 marks

State two ways in which pollution can reduce biodiversity.

1c
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2 marks

The boxes below show a number of pollutants and the ways that they affect ecosystems.

pollution-q-1

Draw a line between each pollutant and the effect that it creates. 

1d
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2 marks

Pesticide levels in the water of a lake were measured at a level of 877 parts per billion.

The same pesticide was measured in the gills of a fish living in that lake and showed biomagnification by a factor of 9.75 million (9 750 000) times.

Calculate the concentration of the pesticide in the fish's gills. Give your answer in standard form. 

1e
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1 mark

Part (d) gives an example of biomagnification, in which the level of a dangerous compound gets higher at successive trophic levels. 

Explain how biomagnification differs from bioaccumulation.

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2a
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2 marks

Separate: Biology Only

State two reasons why deforestation is contributing to an increase in atmospheric CO2 levels.

2b
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1 mark

Which of A - D is not a possible consequence of global warming?

A

Changes in migration patterns of birds

B

Sea level rise

C

Increase in fossil fuel regeneration

D

Habitat loss for certain animals

2c
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2 marks

State and explain the action that carbon dioxide (CO2) and methane (CH4) both have on the atmosphere that causes them to be greenhouses gases. 

2d
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1 mark

Other than CO2 and CH4, name one other greenhouse gas. 

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3a
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3 marks

When raw sewage is released into a waterway it can lead to eutrophication. 

The statements below list some of the stages of the process of eutrophication. 

Complete the table by numbering the statements to put the stages into the correct order. 

Stage of Eutrophication

Order

Algal bloom prevents sunlight from reaching aquatic plants. Water oxygen levels fall

 

Excessive nutrients from fertilisers run-off from the land into the water

 

Algae also show rapid growth

 

Death of organisms requiring dissolved oxygen in water

 

Decomposition rate increases. Aerobic respiration of decomposers reduces dissolved oxygen further

 

Aquatic plants flourish, growing rapidly

 

3b
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2 marks

Explain one other potential consequence of the release of raw sewage into a water system. 

3c
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3 marks

One of the steps of eutrophication involves the decomposing microorganisms carrying out aerobic respiration and depleting the quantity of dissolved oxygen in the water. 

(i) Add the correct words in the gaps in the space below to complete the word equation of aerobic respiration.

............................ + oxygen → ............................ +  ............................

(2)

(ii) Respiration provides energy for the cell processes carried out by these decomposers. 

Name one of these processes that is directly linked to how the decomposers get their nutrition. 

(1)

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4a
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3 marks

The air around us can contain a lot of chemicals that can be harmful to human health. 

Explain the biological consequences of air pollution by sulfur dioxide.

4b
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1 mark

State how sulfur dioxide pollution can be reduced.

4c
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4 marks

Another chemical that contributes to air pollution is carbon monoxide. 

(i) State whether carbon monoxide is a greenhouse gas. Explain your answer. 

(2)

(ii) Explain why carbon monoxide is a harmful air pollutant.

(2)

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1a
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2 marks

Large quantities of food are wasted every year. Waste food needs to be disposed of using methods that do not harm the environment.

The table shows the mass of each gas released into the air from three different methods of waste disposal.

Method of waste disposal

Mass of each gas released into the air from 1000 kg of waste food in kg

Carbon dioxide

Carbon monoxide

Methane

Sulfur dioxide

Anaerobic digester

37

0.012

3.05

0.23

Burying in landfill

220

0.680

14.70

3.12

Burning

680

0.059

3.12

0.08

Calculate how much carbon dioxide would be released from 125 kg of waste food when using an anaerobic digester.

Give your answer to two significant figures and in kilograms. 

1b
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5 marks

Some scientists have claimed that anaerobic digesters are the most environmentally friendly method of waste disposal.

Evaluate this claim using data from the table and your own knowledge.

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2a
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4 marks

Farmers may add chemical fertilisers to their soil.

Explain how chemical fertilisers can increase crop yield.

2b
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4 marks

These fertilisers may leak into rivers.

A scientist measures the oxygen content of water in two different locations of the same river during the month of April.

4bi1br-nov-2020-q10b-fertiliser---sq

In location A he finds that the mean dissolved oxygen was 6 mg per litre and at location B he finds that the mean dissolved oxygen was 3 mg per litre.

He concludes that the use of fertiliser in the field has affected the oxygen content of the river.

Discuss his conclusion.

2c
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1 mark

Some farmers use alternative substances to chemical fertilisers.

Suggest one alternative substance that a farmer may use.

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3a
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2 marks

Separate: Biology Only

Deforestation is a major contributor to the general decline of biodiversity worldwide. 

Suggest two ways in which deforestation impact biodiversity negatively. 

3b
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3 marks

Separate: Biology Only

Data from the United Nations suggests that globally, we are losing 88 000 km2 of natural forest every year to timber and paper production, and to clearance of land for crops and livestock grazing.

A football pitch has an area of 7 140 m2.

Calculate the time taken, at the current rate of deforestation, for a football pitch-sized piece of land to be deforested. Give your answer to the nearest whole second. 

3c
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4 marks

Separate: Biology Only

Deforestation can lead to soil erosion. 

Describe how soil erosion occurs and explain the effect of soil erosion on the environment. 

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4a
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3 marks

There is a general consensus amongst the scientific community that increased levels of carbon dioxide emissions, as a result of human activity, are causing global warming due to an enhanced greenhouse effect. 

Explain how increases in the proportions of greenhouse gases in the atmosphere have led to global warming.

4b
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2 marks

Global warming, and the climate change that it brings, have an overall detrimental effect on biodiversity and ecology in general.

Suggest and explain one effect of global warming that may be beneficial to an individual species.

4c
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5 marks

The graph below shows the total greenhouse gas emissions from Europe and China from the years 1990 to 2019.

The emission data is given using the unit billion tonnes. 

greenhouse-gas-emission-graph-europe-and-china-sqgreenhouse-gas-emission-graph-europe-and-china-sq

(i) Describe the data in the graph. 

(3)

(ii)Give two reasons that could explain the trends shown in the graph. 

(2)

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5a
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2 marks

The diagram shows a river and the location of a fertiliser factory. The arrows indicate the direction of the flow of the river.

zs9DJTQl_1

A scientist recorded the nitrate concentrations of the water at site A and site B. Her results are shown in the table.

Site

Nitrate concentration / mg per dm3

Sample 1

Sample 2

Sample 3

Mean

A

17

25

18

20

B

49

64

58

 

Calculate the mean nitrate concentration found at site B.

5b
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4 marks

The scientist observed algae and some dead fish in the river at site B. These were not present at site A.

Give an explanation for these observations.

5c
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4 marks

Scientists carried out another test and found higher than normal levels of sulfuric acid dissolved in the water in the stream at both sites. 

Explain a series of events that could have led to sulfuric acid washing into the river. 

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1a
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1 mark

Separate: Biology Only

The graph below shows the area of forest land lost in Ecuador in the years 2014 - 2019 inclusive. 

ecuador-deforestation-1

Determine the total area of land lost to deforestation in Ecuador from the beginning of 2014 to the end of 2019. 

1b
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2 marks

Separate: Biology Only

Complete the table by placing a tick (✓) in the relevant boxes below to identify possible reasons for the change in the area of forest lost per year between 2014 and 2017.

The local people stop growing maize

 

Less new house-building is needed for the population

 

The local people decided to farm sheep and goats

 

More trees have been planted

 

A company starts growing sugar cane for the production of biofuel

 

1c
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2 marks

Separate: Biology Only

Suggest two explanations for the reduction in loss of forest land in Ecuador in the years 2018 and 2019. 

1d
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2 marks

Separate: Biology Only

Some government officials looked at the graph in part (a) in late 2019 and concluded that the forest was starting to recover.

Explain why this conclusion may be incorrect. 

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2a
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2 marks

Cutting down trees, known as deforestation, causes an increase in the level of carbon dioxide (CO2) in the atmosphere.

Give two reasons why deforestation causes an increase in atmospheric CO2.

2b
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5 marks

A dairy farmer hoses down the floors of his milking shed at the end of each day's milking. The waste water flows from the shed floor and is pumped into a storage tank. This waste water contains urine and faeces from the cattle.

On one occasion the waste water storage tank overflowed and entered a nearby stream. 

Explain the effect that this event will have on the plants and animals living in the stream.

2c
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4 marks

Farmers keep cows to produce milk.

Injecting cows with growth hormone (GH) will increase milk production.

This allows farmers to obtain the same volume of milk from fewer cows.

Digestion in cows releases methane gas into the atmosphere.

A scientist claims that injecting GH into cows would reduce climate change.

Comment on this claim.

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3a
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4 marks

The table below gives data about how the carbon dioxide (CO2) concentration of the earth's atmosphere has changed over time. 

Year

CO2 concentration in parts per million

1800

282

1900

295

1950

310

2000

370

2020

410

2022

420

Plot the data from the table on the graph paper provided below. 

blank-graph-paper-7x8-big-squares
3b
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3 marks

Explain why carbon dioxide concentrations in the atmosphere are changing.

3c
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2 marks

In 2022 a climate activist claimed that, to arrest global warming, the atmospheric CO2 level should be brought back to the level of the year 1900.

Using the data from the table in part (a), calculate the percentage decrease that the climate activist claims would be needed to return the atmospheric CO2 level to its 1900 level. 

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4a
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2 marks

When fossil fuels are burned sulfur dioxide gas (SO2) can also be released into the atmosphere. 

Flue gases from the burning process can be captured and desulfurised, a process which traps the flue gases and reacts with the sulfur dioxide with calcium hydroxide.

A further step results in the formation of calcium sulfate which is a major component of plasterboard used in the building industry. 

Ca(OH)2(s) + SO2(g) → CaSO3(s) + H2O(l)

Apart from supplying the building industry, explain one benefit of the process of flue gas desulfurisation. 

4b
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3 marks

Describe the potential consequences for living organisms of failing to carry out flue gas desulfurisation. 

4c
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5 marks

There are currently two main ways in which household rubbish is disposed of by local authorities in the UK.

These are:

  • Landfill: rubbish is buried underground

  • Incineration: rubbish is burned at 1000 °C

The table below outlines some of the features of both methods. 

Landfill

Incineration

Traditional, trusted

A newer method

Needs a large hole in the ground, e.g. a disused quarry

Involves a high-tech incineration plant

Generates CO2 and methane as organic waste decays

Generates a lot of CO2

Causes odours and insect/rat infestations

Clean-burning can mean that few pollutants are emitted to the atmosphere/rivers

Requires waste to be transported a long way, even exported

Generates heat and electricity for the local grid

Suitable sites are running out

Unpopular with local people

Toxins can be leached from landfill sites when water runs through a site

Can be set up in all localities

Use the data in the table and your knowledge of waste treatment to evaluate both methods of waste disposal. 

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