Question 1
Which part of a leaf contains the most chloroplasts?
- Upper epidermis
- Palisade mesophyll
- Spongy mesophyll
- Guard cells
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Answer: B (1)
Question 2
State two ways in which most leaves are adapted for photosynthesis because of their shape, and explain one of them.
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- large surface area (1)
- thin (1)
- large surface area absorbs more light / thin so light reaches all cells / thin so short distance for carbon dioxide to diffuse (1)
Question 3
The diagram of a leaf cross-section has four labelled parts: W (upper epidermis), X (palisade mesophyll), Y (air spaces) and Z (stoma). Describe the function of each part in photosynthesis. [4]
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- W: transparent / lets light through to the cells below (1)
- X: contains many chloroplasts / absorbs light for photosynthesis (1)
- Y: allow carbon dioxide to diffuse through to the cells (1)
- Z: allows carbon dioxide to enter (and oxygen to leave) (1)
Question 4
(a) Name the two tissues found in the vascular bundle of a leaf. [1] (b) State the role of each tissue in a leaf. [2] (c) Explain why the cells of the palisade mesophyll are close to the upper surface of the leaf. [2]
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- (a) xylem and phloem (1)
- (b) xylem: brings water to the leaf (1)
- (b) phloem: carries sucrose / products of photosynthesis away from the leaf (1)
- (c) this is where the most light reaches (1)
- (c) so more light is absorbed by the chloroplasts for photosynthesis (1)
Question 5
What is the main function of the guard cells?
- to absorb light
- to open and close the stomata
- to carry water to the leaf
- to store starch
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Answer: B (1)