A golden grain
317 words over 30 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.
A golden grain
In many countries rice is eaten at almost every meal. White rice is a
good source of starch, but it contains no beta-carotene, the orange
pigment that the human body converts into vitamin A. Children who lack
vitamin A can lose their sight, and they are more likely to die from
infections such as measles. Hundreds of thousands of children around
the world become blind each year because their diet lacks vitamin A.
Rice plants already make beta-carotene in their leaves, but not in the
grain that people eat. In the 1990s, scientists set out to change
this. They took a gene from daffodils and a gene from a soil
bacterium, both coding for enzymes needed to make beta-carotene. The
genes were inserted into a plasmid, and the plasmid was used as a
vector to carry them into rice cells. Plants grown from these cells
produced yellow grains, so the new variety was called Golden Rice.
Because it contains genes from other species, it is a transgenic
organism.
The first Golden Rice contained only a small amount of beta-carotene.
A few years later, the scientists replaced the daffodil gene with a
similar gene from maize, and the new variety made much more. The
amounts are shown in Figure 1.
In 2021 the Philippines became the first country to approve Golden
Rice for farmers to grow. Supporters say that it could prevent
blindness in poor communities at little cost, because farmers can save
seed from their own crop. Opponents worry that genes could spread to
wild relatives of rice by pollination, and that people should be
encouraged to eat a more varied diet with vegetables and fruit
instead.
Other genetically modified crops include maize that is resistant to
insect pests and soya that is resistant to a herbicide. In many
countries, a new GM crop must be tested for several years before
farmers are allowed to grow it.
Figure 1 Beta-carotene in the grain of three types of rice
| Type of rice | Beta-carotene / µg per g of dry grain |
|---|---|
| White rice | 0 |
| First Golden Rice (daffodil gene) | 1.6 |
| Golden Rice 2 (maize gene) | 31 |
Figure 1 uses values reported in Ye X et al. (2000) Science 287: 303–305 and Paine JA et al. (2005) Nature Biotechnology 23: 482–487. The article text is illustrative.
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 transgenic.
(1)Name the enzyme used to join a gene into a plasmid.
(1)Describe how a gene from a daffodil could be transferred into rice cells.
(3)Use Figure 1 to calculate how many times more beta-carotene Golden Rice 2 contains than the first Golden Rice. Give your answer to one decimal place.
(2)Explain why Golden Rice could reduce blindness in communities where rice is the main food.
(2)Suggest three reasons why some people oppose growing genetically modified crops such as Golden Rice.
(3)Total for this question: 12 marks
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