Who will pollinate the apples?
311 words over 29 numbered lines, then 6 parts worth 12 marks (Modular Unit 2 (4WBI2) style, 12–13 marks). Read the article, answer each part, then open its mark scheme and set your mark.
Illustrative article written for Scholar Lab, not a Pearson text. The biology is real; the studies, people and figures are invented or rounded for practice unless a source is named.
Who will pollinate the apples?
Every spring, apple orchards are covered in pink and white blossom.
Each flower has brightly coloured petals, a sweet scent and nectar at
its base. These features attract insects such as bees and hoverflies,
which visit the flowers to feed.
As an insect pushes into a flower, sticky pollen grains from the
anthers cling to its hairy body. When the insect visits the next
flower, some of this pollen is brushed onto the stigma. The transfer
of pollen from an anther to a stigma is called pollination. Most apple
varieties produce fruit only if they receive pollen from a different
variety, so growers plant at least two varieties close together.
After pollination, a pollen tube grows from the pollen grain down
through the style to an ovule inside the ovary. A male nucleus travels
down the tube and fuses with the female nucleus in the ovule. After
fertilisation, each ovule develops into a seed, and the ovary develops
into the fruit around the seeds.
In an illustrative study, a grower investigated how much her crop
depended on insects. On several trees she covered some branches of
flowers with fine mesh bags before the flowers opened, so that insects
could not reach them. Other flowers were left open, and a third group
was pollinated by hand with a small brush. She counted how many
flowers on each branch developed into fruit. Her results are shown in
Figure 1.
In some parts of the world, the numbers of wild bees have fallen
because of habitat loss, disease and the use of pesticides. Some
growers now plant strips of wild flowers between the rows of trees to
provide food for pollinating insects all year round. In a few regions
where wild bees have almost disappeared, workers climb ladders and
pollinate fruit trees by hand, one flower at a time, which is slow and
expensive.
Figure 1 Percentage of apple flowers that developed into fruit
Read the article and study the figure. Use the information in the article and your own knowledge to answer the questions. The lines in brackets show where to look; select them to highlight the text.
Use the information in the article and your own knowledge to answer the questions. The lines in brackets show you where to look; select them to highlight the text.
State what is meant by the term pollination.
(1)Give two features of apple flowers that show they are pollinated by insects.
(2)Describe what happens after pollination for an ovule to be fertilised.
(3)Use Figure 1 to calculate how many times more flowers developed into fruit when left open than when covered with mesh bags.
(2)Explain why very few flowers in mesh bags developed into fruit.
(2)Suggest why more flowers developed into fruit when pollinated by hand than when left open, as shown in Figure 1.
(2)Total for this question: 12 marks
0 / 12 marks · 0 of 6 parts rated
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