Describe the induced-fit model of enzyme action and how an enzyme acts as a
catalyst.
[3 marks]
0 1 . 2 Scientists investigated the action of the
... [Show More] enzyme ATP synthase. They made reaction
mixtures each containing:
• ATP synthase
• buffer (to control pH)
• substrates.
One of the substrates required in these reaction mixtures is inorganic phosphate (Pi).
Tick () one box to show which other substrate the scientists must add to the reaction
mixtures to produce ATP.
[1 mark]
Adenine
Adenosine diphosphate
Glucose
Ribose
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box 0 1 . 3 The scientists investigated the effect of concentration of inorganic phosphate (Pi) on
ATP synthase activity.
After 2 minutes, they stopped each reaction and then measured the concentration of
ATP.
Figure 1 shows the scientists’ results.
Figure 1
Suggest and explain a procedure the scientists could have used to stop each reaction.
[2 marks]
0 1 . 4 Explain the change in ATP concentration with increasing inorganic phosphate
concentration.
[2 marks]
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box 0 2 . 1 Explain the advantage for larger animals of having a specialised system that
facilitates oxygen uptake.
[2 marks]
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Figure 2 shows two models of oxygen uptake found in animals. box
Figure 2
0 2 . 2 Suggest how the environmental conditions have resulted in adaptations of systems
using Model A rather than Model B.
[2 marks]
Question 2 continues on the next page
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0 2 box . 3 Figure 3 shows changes in concentration of oxygen in two gas exchange systems.
Figure 3
A student studied Figure 3 and concluded that the fish gas exchange system is more
efficient than the human gas exchange system.
Use Figure 3 to justify this conclusion.
[2 marks]
0 2 . 4 Explain how the counter-current principle allows efficient oxygen uptake in the
fish gas exchange system.
[2 marks]
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box 0 2 . 5 Table 1 shows features of two mammals.
Bats are flying mammals; shrews are ground-living mammals.
Table 1
Mammal Mean body mass / kg Mean lung volume / cm3
Bat 0.096 12.48
Shrew 0.024 0.72
Calculate how many times the lung volume per unit of body mass of the bat is greater
than that of the shrew.
Give your answer to an appropriate number of significant figures.
Give one suggestion to explain this difference.
[3 marks]
Answer
Explanation
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0 3 box . 1 Describe how one amino acid is added to a polypeptide that is being formed at a
ribosome during translation.
[3 marks [Show Less]