O-LevelBiologyGenetics & Variation5090/22 · May/June 2017 · Q39 Marks

Fig. 3.1 shows flowers from the same species of plant at different stages, D and E, in their development. [Figure 3.1]

(a)On Fig. 3.1, use lines labelled S and C to label a sepal (S) and a carpel (C).[2]
(b)The flowers are cross-pollinated by an insect. Explain why the insect must visit flower D before visiting flower E.[3]
(c)Suggest how flowers of this species are adapted to be pollinated by an insect such as a bee.[4]

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Mark scheme

Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.

[2] (a) line ending either on or in sepal + labelled either 'S' or 'sepal'; line ending either on or in carpel + labelled either 'C' or 'carpel' ;
[3] (b) (flower D) 1 anther(s)/stamen(s); 2 pollen + mature / produced / present / released / collected; 3 stigma + closed / immature AW / does not receive pollen ; (flower E) 4 stigma + open / mature / receives pollen; 5 anthers + withered AW OR reference to no pollen produced / present / released / to be collected;
[4] (c) 1 large + petal(s); 2 reference to insect / bee landing AW on petal; 3 colour(ful) + petal(s); 4 reference to scent / smell; 5 reference to nectar(ies) / (nectar) guides ; 6 pollen + stick(y) / hooked (to attach to insect / bee); 7 insect / bee makes contact AW with anther / stigma + while collecting nectar;

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