In a plant-breeding laboratory, students transfer pollen from a purple-flowered bean plant to the stigma of a white-flowered bean plant. Fig. 1 shows events...
Question 1 Report
In a plant-breeding laboratory, students transfer pollen from a purple-flowered bean plant to the stigma of a white-flowered bean plant. Fig. 1 shows events inside the receiving flower after pollen has landed. The ovary will later become a pod only if fertilisation occurs. The breeder covers the flower with a paper bag immediately after adding the chosen pollen, so insects cannot bring pollen from another plant.
(a) Complete the sequence by writing the missing biological terms: pollen grain germinates, a __________ grows down the style, a male __________ enters an ovule, then __________ occurs. [3]
(b) Explain why the paper bag helps the breeder obtain seeds from the intended cross. [2]
(c) Describe what happens to the ovule and ovary after successful fertilisation. [2]
(d) State one advantage of producing many seeds in a bean pod. [1]
Answer Details
(a) The completed sequence is: a pollen tube grows down the style; a male nucleus enters an ovule; then fertilisation occurs. [3]
(b) The paper bag stops insects depositing unwanted pollen from other plants on the stigma. [1] Therefore egg cells are fertilised by pollen from the selected purple-flowered plant, so the seeds come from the intended cross. [1]
(c) After successful fertilisation, the ovule develops into a seed [1] and the ovary develops into a fruit, the bean pod. [1]
(d) Producing many seeds increases the chance that some will germinate successfully. [1] It also increases the chance that some are dispersed to suitable places, or survive if others are eaten or damaged.
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