2.16 Plant tissues and the leaf
6 exam questions worth 11 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
0 / 11
Explain why the palisade mesophyll cells are near the top of the leaf and contain many chloroplasts.
Mark scheme
- near the top so they receive the most light (1)
- many chloroplasts to absorb (more) light for photosynthesis (1)
Model answer
Being near the top means they receive the most light, and having many chloroplasts lets them absorb as much light as possible for photosynthesis.
Explain how the spongy mesophyll is adapted for gas exchange.
Mark scheme
- air spaces (1)
- let gases / CO2 diffuse to (and from) cells / give a large surface area (1)
Model answer
The spongy mesophyll has air spaces between the cells, which let carbon dioxide diffuse to the cells and give a large surface area for gas exchange.
What is the function of the waxy cuticle?
Choose one answer.
Correct Not quite: the answer is To reduce water loss
Mark scheme
B
Model answer
B: it reduces water loss by evaporation.
Describe how guard cells close a stoma when a plant is short of water.
Mark scheme
- guard cells lose water / become flaccid (1)
- they change shape / straighten and close the stoma (1)
Model answer
When water is short, the guard cells lose water and become flaccid. They change shape and come together, closing the stoma.
Give two gases that pass through open stomata, and the direction each moves during photosynthesis.
Mark scheme
- carbon dioxide into the leaf (1)
- oxygen / water vapour out of the leaf (1)
Model answer
Carbon dioxide diffuses into the leaf, and oxygen diffuses out.
Where is meristem tissue found, and why is it important?
Mark scheme
- tips of roots and shoots (1)
- cells divide (by mitosis) / stem cells that differentiate, so the plant can grow (1)
Model answer
Meristem tissue is at the tips of roots and shoots. Its cells divide and can become any type of plant cell, so the plant can grow.
Found a mistake?