O-LevelBiologyPlant Nutrition5090/22 · Oct/Nov 2015 · Q412 Marks

Fig. 4.1 shows a section through the leaf of a plant. [Figure 4.1]

(a)(i)the region containing cells with the greatest number of chloroplasts[1]
(a)(ii)two regions that contain cells with no chloroplasts.[1]
(b)Explain why Fig. 4.1 shows the leaf during daylight hours.[1]
(c)(i)Identify the tissues labelled H and I. H I[2]
(c)(ii)Describe the functions of these two tissues.[4]
(d)Name a gas that gradually increases in concentration in the air space during the hours of darkness. Give an explanation for your answer. gas explanation[3]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.

[1] L;
[1] any 2 from: G, H, I;
[1] stomata/J/guard cells open ORA ;
[2] H – xylem; I - phloem;
[max 4] (H) carries water ; minerals/salts/ions; (provides) support; (I) carries sucrose/sugar; amino acids; to/from leaf (phloem only) / rest of plant/through plant;
[3] carbon dioxide; from respiration; OR water vapour ; from transpiration (stream) ; cannot escape/stomata or guard cells closed ;

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