Practise 28 exam-style questions on Abiotic factors for AQA GCSE Biology. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
28 questions
2–4 marks each
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20 questions, marked as you go
Sample questions with model answers
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
Question 1
2 marks
Explain how carbon dioxide concentration in the atmosphere acts as a limiting abiotic factor for plant growth.
Model answer
CO2 is a substrate for photosynthesis; at low CO2 rates of photosynthesis are limited so growth is reduced; when CO2 increases up to saturation, photosynthesis and therefore growth increase until another factor becomes limiting.
Explanation
CO2 concentration restricts carbon fixation; if CO2 is low plants cannot photosynthesise at maximum rate, constraining biomass production until CO2 or some other resource is adequate.
Mark scheme
1 mark
CO2 is required for photosynthesis; low CO2 limits photosynthetic rate
Link CO2 to photosynthesis essential.
1 mark
increased CO2 increases photosynthesis and growth until another factor limits
Accept concept of limiting factor and saturation.
Question 2
3 marks
How does competition for a single limiting abiotic factor (e.g. soil phosphorus) alter species distribution in a community?
Model answer
species that can tolerate low phosphorus or acquire it efficiently will dominate where phosphorus is low; other species are outcompeted and restricted to niches with higher phosphorus; overall diversity may change.
Explanation
When phosphorus limits growth, species adapted to low-P conditions outcompete others, shifting distributions and potentially reducing diversity in affected areas.
Mark scheme
1 mark
species with better phosphorus uptake / tolerance win competition
Mention uptake efficiency or tolerance.
1 mark
less competitive species are excluded or restricted to different areas (niches)
Accept local exclusion or reduced abundance.
1 mark
changes species distribution and may alter diversity
Accept reduced presence or altered community composition.
Question 3
4 marks
Describe two structural adaptations a plant in a windy, coastal habitat might have and explain how each adaptation reduces water loss or wind damage.
Model answer
thick waxy cuticle reduces transpiration by limiting water loss; small or needle-shaped leaves reduce surface area and wind drag; flexible stems reduce breakage in strong winds; deep roots anchor plant and access water.
Explanation
Waxy cuticles and reduced leaf area lower water loss by transpiration; flexible stems and strong roots prevent physical damage from wind and secure the plant in sandy soils.
Mark scheme
1 mark
thick waxy cuticle reduces water loss
Accept cuticle, thicker epidermis, or waxy leaves.
1 mark
small/needle leaves reduce surface area and wind drag or reduce transpiration
Either wind drag or reduced transpiration explanation acceptable.
1 mark
flexible stems reduce breakage in wind
Accept bending rather than breaking; woody flexibility.
1 mark
deep / extensive roots anchor plant and access water
Accept tap root or spreading roots for anchorage and water uptake.
Question 4
4 marks
A scientist measures oxygen in a fish tank at different temperatures and finds O2 decreases as temperature rises. Explain two abiotic reasons for this observation.
Model answer
warmer water holds less dissolved oxygen (physical solubility decreases with temperature); higher temperature increases metabolic rates of organisms and microbes, increasing O2 consumption; both reduce dissolved O2 concentration.
Explanation
Higher temperatures lower O2 solubility and raise organismal respiration rates, increasing oxygen consumption and causing dissolved oxygen levels to decline.
Mark scheme
1 mark
warmer water holds less dissolved oxygen (decreased solubility)
Physical solubility point required.
1 mark
higher temperature increases metabolic rates ? greater O2 consumption
Link to respiration by fish and microbes.
1 mark
combined effect reduces oxygen concentration
Award for linking both mechanisms to O2 decrease.
1 mark
temperature influences gas exchange with atmosphere (reduced diffusion or stratification)
Accept mention of stratification or reduced reaeration.
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