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(a) State the name given to
(i) the body of the fungus that grows from a single spore
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(ii) the thin threads that make up the body of the fungus.
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(b) Describe how a fungus, such as $T.\ violaceum$, obtains nutrients from the agar medium.
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(c) (i) Suggest why there is a clear area around some of the antibiotics.
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(ii) Explain why antibiotics 1 and 5 would \textbf{not} be chosen to treat the gonorrhoea infection.
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(iii) People who take antibiotics should always be told to complete the treatment rather than stop taking the antibiotics when they feel better.
Suggest why people are given this advice.
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509
544
515
(a) Name organ A and hormones B and C.
A ................................................................................................................
B ................................................................................................................
C ................................................................................................................
(b) (i) Name organ D that stores glucose as glycogen.
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(ii) Suggest why glucose is converted to glycogen rather than kept as glucose inside the cells.
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(c) Name the type of control system used in homeostasis that returns the blood glucose concentration to $80-90 \text{mg per 100 cm}^3$.
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(d) Animal hormones are used in the production of milk and meat. Bovine somatotrophin (BST) is used to increase milk production by cows. The hormone is produced by genetically modified bacteria that contain the cattle gene for making BST. It is used in the United States but is banned for use in the European Union.
(i) Outline how genes, such as the one for BST, are transferred from the cells of cattle (cows) to bacteria.
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(ii) Suggest advantages and disadvantages of using hormones, such as BST, in the production of milk and meat.
advantages ............................................................................................
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disadvantages ........................................................................................
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502
568
566
(a) Explain the meaning of the term transpiration.
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(b) Root hair cells provide a large surface area for the absorption of water from the soil.
Explain, using the term water potential, how water is absorbed from the soil into root hair cells.
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(c) Explain how two features, visible in Fig. 3.1 or Fig. 3.2, are adaptations to the conditions in the Sonoran desert.
feature 1 .....................................................................................................................
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feature 2 .....................................................................................................................
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(d) The stomata of some desert plants, such as the saguaro cactus, open at night and close during the day.
Explain how this allows the cacti to survive in the desert, but limits their growth rate.
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517
593
565
(a) Define the term catalyst.
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(b) (i) Explain why the test-tubes were kept at 30 °C.
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[2]
(ii) Explain why test-tubes 5 and 6 were included in the investigation.
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[2]
(iii) State the conclusions that the students would make from the results of test-tubes 1 to 4.
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[3]
(c) Suggest what would happen to any ammonia that passes into the soil.
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(d) Helicobacter pylori is a bacterium that infects the stomach and causes ulcers.
The bacteria secrete urease that helps them to colonise the stomach lining.
(i) Explain why bacteria do not usually grow inside the stomach.
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[2]
(ii) Suggest how urease helps the bacteria to colonise the stomach.
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[2]
(iii) Explain how the immune system protects against infection by bacteria such as H. pylori.
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[2]
592
599
528
(a) Use the information in Fig. 5.1 to describe the changes in carbon emissions from the burning of fossil fuels between 1800 and 2000.
(b) Explain how the combustion of these compounds contributes to pollution.
hydrocarbons ..........................................................................................................................
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compounds of sulfur ..................................................................................................................
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(c) Explain the need to conserve fossil fuels, such as coal, oil and natural gas.
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591
503
600
The field mustard plant, Brassica rapa, is cross-pollinated by insects.
(a) Describe the advantages of cross-pollination to plants. ....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... [3]
Fig. 6.1 shows the events that follow pollination in B. rapa.
[Image_1: Diagram showing events that follow pollination]
(b) Name
(i) structures A to E.
A ...............................................................................................................................................................
B ...............................................................................................................................................................
C ...............................................................................................................................................................
D ...............................................................................................................................................................
E ............................................................................................................................................................ [5]
(ii) the type of nuclear division that occurs to produce the new cells as the seed grows.
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(c) Explain why the genotypes of the seeds are not all the same.
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When ripe, the seed pod breaks open and the seeds are scattered. Some of the seeds germinate and grow into adult plants, but many do not.
(d) Explain why many seeds released by B. rapa do not germinate and grow into adult plants.
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511
598
595
