Some plants are pollinated by the wind. Grasses and many trees are like this. They do not use insects. Instead the moving air carries their pollen. The poll...
Question 1 Report
Some plants are pollinated by the wind. Grasses and many trees are like this. They do not use insects. Instead the moving air carries their pollen. The pollen blows from one flower to another. The wind cannot be attracted like an insect. So these flowers look very different. They are not bright or scented. They are small and dull. They make very large amounts of light pollen. A student compared a grass flower with a buttercup flower. The buttercup is pollinated by insects. The student was asked why their features are so different. The questions below are about wind pollination.
(a) State what is meant by the term self-pollination. [1]
(b) Describe three features of a wind-pollinated flower and explain how each helps it to be pollinated by the wind. [6]
(c) Explain why wind-pollinated plants need to make very large amounts of pollen. [2]
(d) State one advantage to a plant of cross-pollination over self-pollination. [1]
Answer Details
This question compares wind-pollinated and insect-pollinated flowers and tests the meaning of pollination terms.
(a) Self-pollination is the transfer of pollen from the anther to the stigma of the same flower, or another flower on the same plant [1].
(b) Describe and explain any three features of a wind-pollinated flower (1 mark for each feature, 1 mark for the matching explanation, max 6):
- Large, feathery stigmas that hang outside the flower [1], giving a big surface area to catch pollen carried in the moving air [1].
- Anthers that hang outside the flower on long filaments [1], so that the pollen is exposed and easily blown away by the wind [1].
- Pollen that is small, light and smooth [1], so it is easily carried long distances by the wind [1].
- (Alternatively) small, dull flowers with no bright petals, scent or nectar [1], because there is no need to attract insects [1].
(c) Wind-pollinated plants make very large amounts of pollen because much of the pollen is blown away and lost, or lands somewhere other than a stigma [1]; producing a very large amount makes it likely that at least some grains will reach the stigma of another flower of the same species [1].
(d) One advantage of cross-pollination over self-pollination: it produces more genetic variation in the offspring [1], which can make the population better able to survive changes or disease.
Exam tip: in part (b) each mark for a feature is only awarded with its matching "how it helps" statement, so always pair the structure with its function.
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