A student compared the number of stomata on the upper and lower surfaces of a leaf - Edexcel - GCSE Biology - Question 9 - 2018 - Paper 1
Question 9
A student compared the number of stomata on the upper and lower surfaces of a leaf.
She completed a leaf peel as shown in Figure 22.
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Worked Solution & Example Answer:A student compared the number of stomata on the upper and lower surfaces of a leaf - Edexcel - GCSE Biology - Question 9 - 2018 - Paper 1
Step 1
State why a coverslip is placed on top of the leaf peel.
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Answer
A coverslip is placed on top of the leaf peel to keep the leaf peel flat. This ensures that the microscopic details are clearly visible and prevents any movement that could distort the view.
Step 2
Explain why the leaf peel rather than the whole leaf was viewed with a microscope.
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Answer
The leaf peel was viewed rather than the whole leaf because the leaf peel is thinner, allowing light to pass through it. If the whole leaf were viewed, it would obstruct light due to its thickness and would not allow for proper visualization of stomata and cells.
Step 3
State the number of stomata visible on Figure 23.
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Answer
3 / three
Step 4
Describe how stomata open.
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Answer
Stomata open through the action of guard cells. When the plant takes in water through osmosis, the guard cells become turgid and change shape. This causes the stomatal pores to bulge and open, allowing gases to exchange with the environment.
Step 5
Use Figure 24 to help you describe how water and sucrose move through a plant.
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Water moves through a plant primarily via the xylem. It is absorbed from the soil by the roots and then transported upward to the leaves, driven by transpiration. As water evaporates from the leaf surfaces, more water is drawn up through the xylem.
Sucrose, on the other hand, moves through the plant in the phloem. Sucrose is produced in the leaves through photosynthesis and is then transported to various parts of the plant, including roots and growing buds, by active transport in the phloem. This ensures that energy is distributed where it is needed most.
