1
4 marks
4 marksFig. 1 is part of a newspaper article about pollution.
Fig. 1
State four sources of water pollution other than raw sewage.
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Effects of Humans on Ecosystems (Cambridge O Level Biology)
Topic Questions
1a3 marks
3 marksFig.1 shows a river and the location of a fertiliser factory. The arrows indicate the direction of the flow of the river.
Fig. 1
A scientist recorded the nitrate concentrations of the water at site A and site B.
Table 1 shows the results of this investigation.
Table 1
| site | nitrate concentration / mg dm-3 | |||
| sample 1 | sample 2 | sample 3 | mean | |
| A | 16 | 23 | 21 | 20 |
| B | 52 | 71 | 66 | 63 |
Calculate the percentage difference in the mean nitrate concentration between site A and B.
Show your working and state the nature of the difference.
1b4 marks
4 marksScientists observed algae and dead fish at site B.
Suggest an explanation for these observations.
1c3 marks
3 marksExplain the importance of using chemical fertiliser in modern farming practices.
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2a1 mark
1 markThe graph in Fig. 1 shows the area of forest land lost in Ecuador in the years 2014 - 2019 inclusive.
Fig. 1
Calculate the total area of land lost to deforestation in Ecuador from the beginning of 2014 to the end of 2019.
2b2 marks
2 marksIdentify in Table 1 below the possible reasons for the change in the area of forest lost per year between 2014 and 2017.
Place a tick (✓) in the boxes below that apply.
Table 1
| 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 |
2c2 marks
2 marksSuggest two explanations for the reductions in loss of forest land in Ecuador in the years 2018 and 2019.
2d2 marks
2 marksConservationists looking at the data in Fig. 1 would not be fully satisfied with the 2018 - 2019 trend shown in the data.
Explain why.
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1a4 marks
4 marksDeforestation can cause an increase in the concentration of carbon dioxide in the atmosphere.
(i)
State two other undesirable effects of deforestation.
[2]
(ii)
State two uses for land that has been cleared of trees.
[2]
1b5 marks
5 marksThe forests in Brazil contain many endangered species.
Table 1 shows the area of forest that was removed in Brazil each year between 2006–2010.
Table 1
| year | area of forest removed / km2 |
| 2006 | 14 286 |
| 2007 | 12 651 |
| 2008 | 11 911 |
| 2009 | 7 464 |
| 2010 | 7 000 |
(i)
Calculate the average area of forest removed per year from 2006 to 2010.
Give your answer in km2. Show your working.
[2]
(ii)
Describe the trend in the data shown in Table 1.
[1]
(iii)
Suggest two reasons for the trend you have described in part (ii).
[2]
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2a4 marks
4 marksSome animals are farmed intensively.
Describe the negative impacts to an ecosystem of intensive livestock production.
2b3 marks
3 marksState why fertilisers, herbicides and insecticides are used in farming.
2c2 marks
2 marksFertilisers, herbicides and insecticides can all pollute water.
List two other sources of water pollution.
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3a4 marks
4 marksFig. 1 shows a photograph of an area where the trees have been cut down.
Fig. 1
(i)
State the name of the type of habitat destruction shown in Fig. 1.
[1]
(ii)
List three undesirable effects of habitat destruction.
[3]
3b3 marks
3 marksState three human activities, other than cutting down large areas of trees, that can cause habitat destruction.
3c3 marks
3 marksHuman activity can cause pollution of the environment.
Table 1 shows some pollutants, the environment they pollute and some of the effects.
Complete Table 1.
Table 1
| pollutant | environment | effect of pollutant on the environment |
| methane | air | |
| herbicides | kills non-targeted plants | |
| water | increased growth of water plants |
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44 marks
A farmer has not used any insecticides or artificial fertilisers on a crop.
Explain ways in which this may help the local environment.
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55 marks
Many scientists predict that, as the world’s human population increases, there will be a shortage of food.
Suggest and explain why an increase in human population is predicted to lead to a global human food shortage.
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