Fig. 1 shows a section through a leaf collected from a young bean plant growing beside a greenhouse window. The student used the section to compare the cell...
Question 1 Report
Fig. 1 shows a section through a leaf collected from a young bean plant growing beside a greenhouse window. The student used the section to compare the cells near the upper surface with the cells near the lower surface. The tightly packed cells below the upper epidermis contain many chloroplasts. Air spaces occur between other cells, and a vein carries water to the leaf and glucose away from it. The plant was watered before the sample was taken so that the leaf was not wilted.
(a) Identify the tissue containing the greatest number of chloroplasts. [1]
(b) Explain why this tissue is close to the upper surface of the leaf. [2]
(c) Use the information in Fig. 1 to give one way in which the air spaces help photosynthesis. [1]
Answer Details
(a) Palisade mesophyll / palisade cells [1] (b) Receives the greatest light intensity [1]; so more light can be absorbed by chloroplasts for photosynthesis [1] (c) Allow carbon dioxide to diffuse through the leaf to photosynthesising cells / allow oxygen to diffuse out [1]
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