Practise Photosynthetic reaction. 11 exam-style questions 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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Complete the word equation for photosynthesis. carbon dioxide + .................... → glucose + ....................
carbon dioxide + water → glucose + oxygen
Name the green substance in chloroplasts that absorbs light.
Chlorophyll
Photosynthesis is the process by which green plants and algae make glucose. Give the word equation for photosynthesis.
carbon dioxide + water → glucose + oxygen
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy6 marks
Photosynthesis takes place in green plants and algae.
(a) Complete the word equation for photosynthesis. carbon dioxide + .................... → glucose + ....................[2]
(b) In which part of a plant cell does photosynthesis take place?[1]
(c) Which is the chemical formula of glucose? Tick (✓) one box.[1]
CO2
C6H12O6
H2O
O2
(d) Photosynthesis is an endothermic reaction. What does endothermic mean?[1]
(e) How is energy transferred to the chloroplasts for photosynthesis?[1]
Show the answer and mark scheme
(a)Answer: carbon dioxide + water → glucose + oxygen
water
oxygen
(b)Answer: Chloroplasts
chloroplast
(c)Answer: C6H12O6
(d)
energy is transferred from the surroundings / is taken in (by the reaction)
(e)Answer: By light
by light
Question 2Medium7 marks
Photosynthesis is described as an endothermic reaction.
(a) Explain why photosynthesis is described as an endothermic reaction.[2]
(b) Name the green substance in chloroplasts that absorbs light.[1]
(c) Give the chemical formulae of the two reactants in photosynthesis.[2]
(d) A student said, 'Plants get their food from the soil.' Use your knowledge of photosynthesis to explain why the student is wrong.[2]
Show the answer and mark scheme
(a)
energy is transferred from the environment / surroundings
to the chloroplasts by light
(b)Answer: Chlorophyll
chlorophyll
(c)Answer: CO2 and H2O
CO2
H2O
(d)
plants make their own food / glucose by photosynthesis
from carbon dioxide (from the air) and water; the soil only supplies water and mineral ions
Question 3Hard3 marks
Two methods can be used to show that chlorophyll is needed for photosynthesis: (1) using a variegated leaf, with green and white areas, from one plant, or (2) comparing a fully green plant with a plant whose leaves have been made pale by growing it without enough light for a long time.
Evaluate the two methods.[3]
Show the answer and mark scheme
the variegated leaf method uses one leaf, so light, carbon dioxide, temperature and species are automatically the same for the green and white areas, giving a fair comparison
the pale-plant method compares two different plants, which could differ in other ways, e.g. age, size or genotype, making it a less controlled comparison
the variegated leaf method more clearly isolates chlorophyll as the only variable being tested
the pale plant could also be weaker simply from prolonged low light, rather than only from the missing chlorophyll, making the result harder to interpret
conclusion, e.g. the variegated leaf method is the more valid test, because it controls more variables