Exam (elaborations)
AQA A Level Biology - Homeostasis Workbook and Answers (2021-22)
- Module
- Homeostasis
- Institution
- AQA
A useful workbook of past paper questions for Homeostasis with the mark scheme. Also includes teacher annotations.
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Q1.Scientists investigated the control of blood glucose concentration in mice. They kept a group of
normal mice without food for 48 hours. After 48 hours, the blood glucose concentrations of the
mice were the same as at the start of the experiment.
(a) Explain how the normal mice prevented their blood glucose concentration falling when
they had not eaten for 48 hours.
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(3)
The scientists then investigated mice with a mutation that prevents their liver cells making
glucose. They kept a group of these mice without food for 48 hours. After 48 hours, the mean
blood glucose concentrations of the mutant mice and the normal mice were the same.
The scientists investigated how blood glucose concentration is controlled in these mutant mice.
An enzyme required for synthesis of glucose is coded for by a gene called PCK1. The scientists
measured the mean amount of mRNA produced from this gene in cells from the kidneys and
intestines of normal mice and mutant mice. They did this with mice that had previously been
without food for 48 hours.
The scientists’ results are shown in the graph.
(b) Use information from the graph to suggest how blood glucose concentration is controlled
in the mutant mice, compared with the normal mice.
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(3)
(c) The scientists performed statistical tests on the data shown in the graph, to see whether
the differences in the amount of mRNA in cells from normal and mutant mice were
significant. Both the probability values they obtained were p<0.01.
Explain what this means about the differences in the amounts of mRNA produced.
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(2)
(Total 8 marks)
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