AQA GCSE Biology (8461), Higher tier · Ecology › Biodiversity and human interaction
Practise Biodiversity. 11 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Estimate how many of the untested species could contain a chemical that could be developed into a useful medicine.
22.4 (about 22)
Complete the sentence. Biodiversity is the variety of all the different ....................... of organisms on Earth, or within an ....................... .
species; ecosystem
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Many human activities are reducing biodiversity.
(a) What is meant by biodiversity? Tick (✓) one box.[1]
The number of individuals of one species in a habitat
The variety of all the different species of organisms on Earth, or within an ecosystem
The mass of living material at each trophic level
The number of different habitats in an area
(b) A high biodiversity helps to keep an ecosystem stable. Give two reasons why.[2]
(c) Give one human activity that reduces biodiversity.[1]
Show the answer and mark scheme
(a)Answer: The variety of all the different species of organisms on Earth, or within an ecosystem
(b)
species depend less on one other species for food
species depend less on one other species for shelter
species depend less on one other species for the maintenance of the physical environment
if one species is lost, other species can replace it / other food sources are available
(c)
deforestation
building
pollution (of air, water or land)
farming large areas with only one crop
destroying peat bogs
quarrying
overfishing / hunting
Question 2Medium7 marks
Students surveyed the invertebrate animals in two ponds, A and B, using the same method. {table} shows the results.
[object Object]
(a) How many species were found in pond B?[1]
(b) A student said: 'Pond B has a higher biodiversity than pond A because more animals were found in it.' Explain why the student is wrong.[2]
(c) Pond B receives run-off water from a farm. Suggest why pond B has a lower biodiversity than pond A.[2]
(d) Explain why an ecosystem with a high biodiversity is more stable.[2]
Show the answer and mark scheme
(a)Answer: 4
4
(b)
biodiversity is the variety / number of different species, not the number of individuals
pond A has more species (7) than pond B (4)
(c)
pollution (e.g. from fertiliser / sewage / pesticides) from the farm
kills some species, so only species that can tolerate the pollution survive
(d)
species are less dependent on one other species for food / shelter
if one species declines, others can use other food sources / replace it, so population sizes stay fairly constant
Question 3Hard9 marks
The future of the human species on Earth relies on us maintaining a good level of biodiversity. Scientists studying a tropical forest estimate that 1 in every 125 plant species contains a chemical that could be developed into a useful medicine. The forest contains about 4000 plant species. 2800 of these species have not yet been tested.
(a) Estimate how many of the untested species could contain a chemical that could be developed into a useful medicine.[2]
(b) Clearing the forest for farming is predicted to destroy 30% of the untested species before they can be tested. A newspaper headline said: 'Forest clearance will destroy 7 new medicines.' Use a calculation and the information given to evaluate this headline.[3]
(c) Give two other reasons why humans depend on maintaining biodiversity.[2]
(d) Only recently have measures been taken to try to stop the reduction in biodiversity. Suggest two reasons why.[2]
Show the answer and mark scheme
(a)Answer: 22.4 (about 22)
2800 ÷ 125
22.4 / about 22
(b)Answer: 22.4 × 0.30 ≈ 7, but the figures are only estimates, so the headline is too certain
22.4 × 0.30 = 6.7, so about 7 is consistent with the scientists' estimates
but '1 in 125' and '30%' are only estimates / predictions, so the real number could be higher or lower
'will destroy' is too certain: the same chemicals may be found in other species or places / could be made artificially
not every useful chemical becomes a medicine: it must pass testing / trials first
(c)
food, e.g. crops, fish, wild animals
materials, e.g. timber, fibres, fuel
pollination of crops by insects
wild relatives of crops carry alleles that are useful for breeding, e.g. for disease resistance
stable ecosystems provide clean water, oxygen, fertile soil or flood protection
(d)
scientists did not have enough data about how quickly species were being lost
the importance of biodiversity to humans was not understood
there is conflict with economic pressures, e.g. land needed for farming / building
protecting biodiversity needs international agreement / cooperation / funding