B9 Ecosystems and Material Cycles

Question 1

What is interdependency?

Answer 1

When organisms in a community depend on each other to survive and reproduce

Question 2

What is an abiotic factor?

Answer 2

Non-living factors

Question 3

What is a biotic factor?

Answer 3

Living factors

Question 4

What are some examples of abiotic factors?

Answer 4

1. Light intensity
2. Temperature

Question 5

What are some examples of biotic factors?

Answer 5

1. Competition
2. Predation

Question 6

What is eutrophication?

Answer 6

1. Fertilisers enter the water, adding excess nitrates
2. These excess nitrates cause algae to grow fast and block out the light
3. Plants can’t photosynthesise due to the lack of light and start to die and decompose
4. With more food available, microorganisms that feed on decomposing plants increase in number and use up oxygen in the water
5. Organisms that need oxygen for aerobic respiration die

Question 7

How can we conserve biodivesity?

Answer 7

1. Reforestation
2. Conservation schemes

Question 8

What are some conservation schemes?

Answer 8

1. Protecting a species’ natural habitat
2. Protecting species in safe areas outside of their natural habitats and introduce captive breeding programmes to increase their numbers

Question 9

What are the advantages of maintaining biodiversity?

Answer 9

1. Protecting the human food supply
2. Ensuring minimal damage to food chains
3. Providing future medicines

Question 10

What is food security?

Answer 10

When there is enough food that is safe for us to eat and has the right balance of nutrition

Question 11

What is the role of nitrogen fixing bacteria?

Answer 11

They are in the root nodules of leguminous plants and turn atmospheric nitrogen into ammonia

Question 12

What is the role of nitrifying bacteria?

Answer 12

They turn ammonia into nitrates

Question 13

What is the role of denitrifying bacteria?

Answer 13

They turn nitrates nitrogen gas, found in water-logged soils

Question 14

What is the role of decomposers?

Answer 14

They decompose proteins and amino acids into ammonia

Question 15

How can farmers increase the amount of nitrates in the soil?

Answer 15

1. Crop rotation with at least one nitrogen-fixing crop
2. Fertilisers (manure and artificial fertilisers)

Question 16

How can you see the levels of water pollution?

Answer 16

Presence of stonefly larvae and freshwater shrimps are good indicators of water pollution because they are very sensitive to the concentration of dissolved oxygen and indicate clean water. Presence of blood worms and sludgeworms indicate high levels of water pollution as they are adapted to live in these polluted conditions

Question 17

How can you see the levels of air pollution?

Answer 17

Presence of lots of lichen, especially bushy lichen indicate clean air as they are sensitive to the sulfur dioxide concentration. Crusty lichen show less clean air. Blackspot fungus is also found on rose leaves and its presence indicates clean air as they are sensitive to the sulfur dioxide concentration in the air

Question 18

What factors affect the rate of decay?

Answer 18

1. Temperature
2. Water content
3. Oxygen availability

Question 19

What are some methods of preserving food?

Answer 19

1. Storing in a fridge in cold temperatures
2. Storing food in airtight containers
3. Drying food by removing water