O LevelBiologyCambridgeTopic Questions19. Relationships of Organisms with one another & with the Environment19.4 Effects of Humans on Ecosystems

Effects of Humans on Ecosystems (Cambridge O Level Biology)

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1
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Which of the following effects is least likely to be as a result of deforestation?

  • A greater risk of flooding.

  • An increase in biodiversity.

  • An increase in soil erosion.

  • An increase in the level of carbon dioxide in the atmosphere.

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2
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A large quantity of non-selective herbicide is spread over a field. However, some of the herbicide washes into a nearby stream.

What is the effect of the herbicide on the weeds in the field and on the plants in the stream?

  weeds in field plants in stream
A more growth less growth
B less growth more growth
C less growth less growth
D more growth more growth

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3
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To increase a farmer’s yield, low concentrations of Insecticides can be sprayed onto their crops, but insecticides may also be harmful to wildlife.

Which of these statements correctly explains why?

  • Insecticides kill other plants.

  • Insecticides cause acid rain.

  • Insecticides enter the food chain.

  • Insecticides increase the nitrates in the soil.

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4
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The image below shows the results of a study on the types of animals found along a stretch of stream near to a factory.

image-2-2

Which animal will live in the most polluted water?

  • Shrimp

  • Sludge worm

  • Leech

  • Snail

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1
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The levels of dissolved oxygen were measured in a river, the results were plotted on a graph, this is shown below. 

At which point does raw sewage enter the river?

image-1-2

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2
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Rapid growth of algae on the surface of the water can occur as a result of nitrates entering a reservoir of water.

This causes the following changes in the reservoir:

  1. An increase in aerobic respiration by decomposers.
  2. A decrease in the concentration of dissolved oxygen in the water.
  3. Fish and other aquatic animals die.
  4. Producers die and decomposition increases.

In which order do these changes occur?

  • 1 → 2 → 4 → 3

  • 3 → 1 → 2 → 4

  • 4 → 1 → 2 → 3

  • 4 → 3 → 1 → 2

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31 mark

Which human activity will make the greatest contribution to global warming?

  • cutting down established trees and replanting with young trees

  • cutting down established trees and using the cleared land to raise cattle

  • reducing the use of diesel fuel in public transport vehicles

  • using fewer insecticides and herbicides on farms

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The graph shows the relationship between the number of lichens and the levels of sulfur dioxide pollution.

jp85qfh8_image-3

Which of these statements best describe the graph?

  • Sulfur dioxide levels do not affect lichen growth.

  • As sulfur dioxide levels increase, the number of lichen decreases.

  • Lichens cannot survive if there is sulfur dioxide present.

  • As sulfur dioxide levels increase, so does the number of lichen.

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2
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The following statements refer to plastic pollution.

  1. Animals will often try to eat the plastic or become entangled in it
  2. It breaks down into micro particles that wash away into nearby rivers
  3. As plastic breaks down, it releases toxins into the surrounding environment
  4. It enters the food chain when filter feeders such as mussels ingest micro particles

Which of these statements applies to both marine and terrestrial (land) habitats?

  • 1, 2 and 3

  • 2 and 4 only

  • 1 and 3 only

  • 3 only

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3
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Which of these agricultural practices may cause the most pollution?

  • Cutting down trees to create space for crops.

  • Adding fertilisers to the soil.

  • Digging plant material into the crop.

  • Growing high yield crops.

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4
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Which of these two gases both contribute to climate change?

  • Oxygen and methane

  • Sulfur dioxide and methane

  • Carbon dioxide and methane

  • Carbon dioxide and sulfur dioxide

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