B18 Biodiversity and Ecosystems

Question 1

What is the benefit of rich biodiversity?

Answer 1

It makes ecosystems more stable

Question 2

3 different places pollution can occur

Answer 2

• in water, from sewage, fertiliser or toxic chemicals
• in air, from smoke and acidic gases
• on land, from landfill and from toxic chemicals.

Question 3

Describe how water pollution can occur

Answer 3

Untreated sewage, chemicals from factories or fertilisers from farms can run of into rivers and streams. These cause dissolved oxygen levels to fall, killing aquatic organisms.

Question 4

Describe how waste from human activities can pollute the air

Answer 4

Burning coal in power stations can release acidic gases, and cause acid rain. Burning can also release smoke. Air pollution can kill animals, reducing biodiversity

Question 5

Describe how human waste can cause land pollution

Answer 5

Millions of tonnes of waste are dumped in landfills, which destroy habitats for plants and animals. Toxic chemicals can also leech out of landfills and pollute the soil

Question 6

How is peat created?

Answer 6

By the incomplete decomposition of the remains of plants growing in waterlogged conditions.

Question 7

What is peat used for?

Answer 7

As fertiliser, and as fuel for energy (as they contain a lot of trapped carbon)

Question 8

How does the destruction of peat bogs reduce biodiversity?

Answer 8

It reduces the area of its (peat bog’s) habitat, reducing the variety of animals, plants and microorganisms that live there.

Question 9

What are the disadvantages of extracting peat?

Answer 9

Reduced biodiversity
Releases carbon dioxide when burnt, contributing to climate change
Non renewable (used faster than it is formed)

Question 10

Why would using peat alternatives be a pain

Answer 10

They are more expensive, and could cause food costs to rise
- Understand the conflict 
between the need for cheap 
available compost to increase 
food production and the need 
to conserve peat bogs and 
peatlands as habitats for 
biodiversity and to reduce 
carbon dioxide emissions.

Question 11

What type of field produces methane?

Answer 11

Paddy fields, that are used to grow rice as the bacteria in them produce methane

Question 12

What is food security?

Answer 12

Having enough food to feed a population

Question 13

A dairy farmer washes out his cow shed each day. The waste water contains urine
and faeces. The waste water overflows into a stream by mistake.
The waste water will have an effect on the plants and invertebrates living in the
stream.
Explain why

Answer 13

• Waste contains mineral ions (and organic matter)
• this increases growth of algae / water plants
• the plants / algae (underneath) die
• due to lack of light / photosynthesis / space
• decomposers / microorganisms feed on decaying matter or multiply rapidly
• the respiration of decomposers uses up all the oxygen
• so invertebrates die due to lack of oxygen
• this is called eutrophication

Question 14

Explain why mixing peat with air releases CO2

Answer 14

decay / decomposition / rotting of peat

by microorganisms / bacteria / microbes / fungi / decomposers introduced when peat
is mixed with air

that respire using substances in peat as reactant

and using oxygen that is introduced when peat is mixed with air

Question 15

How can fertilisers damage ecosystems?

Answer 15

They reduce dissolved oxygen levels, which can kill aqautic

Question 16

Approximately a third of UK domestic rubbish is organic matter such as food waste and
gardening rubbish.
Many councils have started industrial composting schemes to decompose these wastes.
One product of the decomposition is compost (decaying organic matter).
Use this information and your own knowledge to suggest reasons why more councils
should be encouraged to start industrial composting schemes. [3]

Answer 16

Reduces Landfill

produces compost / fertiliser which can be sold

produces nutrients / fertiliser / minerals (ions) for plants

Question 17

Describe two effects of global warming on the human population [6]

Answer 17

climate change
warmer/colder/drier/wetter
food production affected/starvation
mayor ecosystems destroyed/damaged

sea level rise
low land flooded
less food grown/starvation
homes/factories flooded

Question 18

How do humans reduce the amount of land available for other plants and animals?

Answer 18

Building, quarrying, farming and dumping waste

Question 19

Approximately how much biomass is transferred from one trophic level to another?

Answer 19

About 10%

Question 20

In producers, how much incident light energy is transferred for photosynthesis?

Answer 20

about 1% of the incident energy from light for photosynthesis

Question 21

Describe some reasons for losses of biomass

Answer 21

• not all the ingested material is absorbed, some is egested as faeces
• some absorbed material is lost as waste, such as carbon dioxide and
water in respiration and water and urea in urine.
- Large amounts of glucose used in respiration

Question 22

Name biological factors that affect food security

Answer 22

the increasing birth rate has threatened food security in some
countries
• changing diets in developed countries means scarce food resources
are transported around the world
• new pests and pathogens that affect farming
• environmental changes that affect food production, such as
widespread famine occurring in some countries if rains fail
• the cost of agricultural inputs
• conflicts that have arisen in some parts of the world which affect the
availability of water or food.

Question 23

What is food security?

Answer 23

Having enough food to feed a population