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Biology

CAIE2024

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Biology

CAIE2024

24 48 72 time / hours Fig. 2.1 Fig. 2.1 shows that the percentage of open stomata increases in the first seven hours of the experiment. Describe the sequence of changes that occurs in the guard cells that leads to the stomata opening. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... (cid:300)(cid:205)(cid:266)(cid:190)(cid:288)(cid:180)(cid:237)(cid:200)(cid:245)(cid:207)(cid:298)(cid:197)(cid:266)(cid:223)(cid:252)(cid:183)(cid:256)(cid:215) © UCLES 2024 (cid:300)(cid:228)(cid:199)(cid:251)(cid:214)(cid:295)(cid:268)(cid:269)(cid:210)(cid:241)(cid:249)(cid:282)(cid:246)(cid:295)(cid:185)(cid:299)(cid:269)(cid:258) 9700/43/O/N/24 (cid:293)(cid:293)(cid:197)(cid:277)(cid:245)(cid:277)(cid:293)(cid:245)(cid:197)(cid:245)(cid:229)(cid:197)(cid:197)(cid:245)(cid:293)(cid:181)(cid:181)(cid:213) NIGRAM SIHT NI ETIRW TON OD NIGRAM SIHT NI ETIRW TON OD NIGRAM SIHT NI ETIRW TON OD NIGRAM SIHT NI ETIRW TON OD NIGRAM SIHT NI ETIRW TON OD PMT * 0000800000005 *

Question

Biology

CAIE2016

Fig. 4.1 shows a diagram of a stoma, its guard cells and adjacent epidermal cells. stoma nucleus cytoplasm epidermal cell guard cells nucleus Fig. 4.1 (a) Guard cells have chloroplasts while epidermal cells do not have chloroplasts. State one other difference, visible in Fig. 4.1, between guard cells and epidermal cells. ................................................................................................................................................... .............................................................................................................................................. [1] (b) During stomatal closure: (i) state precisely where abscisic acid (ABA) binds ...................................................................................................................................... [1] (ii) identify the ion that diffuses from the guard cells to epidermal cells ...................................................................................................................................... [1] (iii) compare the relative water potential of the guard cells with that of epidermal cells .......................................................................................................................................[1] (iv) describe the change in volume of the guard cells. ...................................................................................................................................... [1] © UCLES 2014 9700/04/SP/16 [Turn over PPMMTT

Question

Biology

CAIE2016

The Venus fl y trap, Dionaea muscipula, is a carnivorous plant. It has traps which catch insects. Each trap consists of a pair of modifi ed leaves joined by a midrib of hinge cells. The modifi ed leaves have touch-sensitive hairs. If two hairs are touched within 20 seconds, or the same hair is touched twice in rapid succession, the trap closes. (a) Explain how touching the hairs results in closure of the trap. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [5] © UCLES 2014 9700/04/SP/16 PPMMTT

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