Practise 30 exam-style questions on Plant tissues 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.
30 questions
2–4 marks each
Instant marking
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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
Why are stomata generally found on the lower epidermis of many leaves?
Model answer
Lower epidermis reduces water loss because it is shaded and cooler; reduces direct exposure to sun and wind.
Explanation
Placing stomata on the lower (shaded) surface reduces transpiration because it is cooler and less exposed to sunlight and wind, reducing water loss while allowing gas exchange.
Mark scheme
1 mark
Reduces water loss / conserves water
1 mark
Lower surface is cooler/shaded/less windy so less evaporation
Question 2
3 marks
A student examines a cross-section of a leaf. They find a layer of elongate cells packed full of chloroplasts. Identify this layer and explain its advantage.
Model answer
Palisade mesophyll; many chloroplasts maximise light absorption for photosynthesis.
Explanation
Palisade mesophyll cells are long and contain many chloroplasts so they capture more light, increasing the rate of photosynthesis.
Mark scheme
1 mark
Palisade mesophyll
2 marks
Packed with chloroplasts to maximise light absorption for photosynthesis
award if both idea of many chloroplasts and effect (maximise absorption/photosynthesis) present
Question 3
3 marks
Why might a plant grown in low light develop thinner leaves with fewer palisade layers?
Model answer
Low light reduces the need for many palisade layers; plant conserves resources and invests in larger leaf area rather than thick palisade regions; fewer chloroplasts needed per cell.
Explanation
In shade, plants often make thinner leaves with fewer palisade layers because extra layers would not increase photosynthesis proportionally; instead they optimise leaf area and resource allocation.
Mark scheme
1 mark
Less light means less need for many palisade layers / chloroplasts
1 mark
Plant reduces energy/resource investment in thickness
1 mark
May develop larger leaf area instead to capture more light
Question 4
4 marks
Design a valid experiment to investigate how light intensity affects stomatal opening. Include independent, dependent and a control.
Model answer
Independent: light intensity (use lamps at different distances or strengths); Dependent: stomatal aperture or number of open stomata per unit area measured from epidermal peel; control: leaf temperature, humidity, same species/age. Repeat and calculate mean.
Explanation
Vary light intensity while keeping other conditions constant, examine epidermal peels under microscope to measure stomatal aperture or count open stomata, use replicates to ensure reliability.
Mark scheme
1 mark
Independent: light intensity (different levels)
1 mark
Dependent: measure stomatal opening (aperture) or count open stomata per area
1 mark
Control: keep temperature, humidity, species, leaf age constant
1 mark
Repeat and calculate mean / use replicates
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