This image is a stained view of onion leaf cells taken by a student using a light microscope. The cells form one layer on the outside of the leaf. Some pair...
Question 1 Report
This image is a stained view of onion leaf cells taken by a student using a light microscope. The cells form one layer on the outside of the leaf. Some pairs of curved cells surround a gap. The student observed the leaf during a hot afternoon when the plant had little water available.
(a) Identify the specialised cells labelled X. [1]
(b) Explain why the gap between these cells may become smaller when water is scarce. [2]
(c) Use the figure to identify one structure found in every plant cell shown. [1]
(d) Which process causes water to enter or leave the specialised cells? [1]
Answer Details
(a) Guard cells [1] (b) Water leaves guard cells by osmosis [1]; cells become less turgid so the pore closes / narrows [1] (c) Cell wall / cell membrane / cytoplasm / nucleus / vacuole [1] (d) Osmosis [1]
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