Describe the process of glycolysis.
[4 marks]
0 1 . 2 Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake
... [Show More] of oxygen in a respiring cell.
[2 marks]
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0 2 box . 1 Explain how a resting potential is maintained across the axon membrane in a
neurone.
[3 marks]
0 2 . 2 Explain why the speed of transmission of impulses is faster along a myelinated axon
than along a non-myelinated axon.
[3 marks]
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box 0 2 . 3 A scientist investigated the effect of inhibitors on neurones. She added a respiratory
inhibitor to a neurone. The resting potential of the neurone changed from –70 mV
to 0 mV.
Explain why.
[3 marks]
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box 0 3 Figure 1 shows an investigation into growth factors in plants.
Figure 1
0 3 . 1 Use your knowledge of indoleacetic acid (IAA) to explain the growth curvature shown
in Figure 1.
[3 marks]
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A bioassay is a method to determine the concentration of a substance by its effect on box
living tissues.
Figure 2 shows the practical procedure used in a growth curvature bioassay to
determine the concentration of IAA in shoot tips.
Figure 2
Figure 3 shows the calibration curve for this growth curvature bioassay.
Figure 3
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box 0 3 . 2 Using the procedure in Figure 2 and the calibration curve in Figure 3, describe how
you could compare the IAA concentration in shoot tips from two different plant
species.
In your answer you should refer to all the variables that should be controlled to
produce a valid comparison.
[5 marks]
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A scientist investigated the effect of a directional light stimulus on the distribution of box
IAA in shoot tips. The scientist set up three experiments as shown in Figure 4.
All variables were controlled apart from exposure to light.
Figure 4
She then used the growth curvature bioassay to compare the IAA concentrations in
the agar blocks from:
• experiment 1
• experiment 2
• experiment 3 section A
• experiment 3 section B.
Table 1 shows the scientist’s results.
Table 1
Experiment Degree of curvature in
Bioassay / degrees
1 17.69
2 17.61
3A 11.22
3B 6.50
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box 0 3 . 3 State two conclusions about IAA that you can make from the results shown in
Table 1.
[2 mar [Show Less]