B2 2021

Question 1

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 -70mV to 0mV. Why?

Answer 1

Because less ATP is produced by aerobic respiration
Less active transport
Electrochemical gradient not maintained

Question 2

3.2 Describe how you could compare the IAA concentration in shoot tips from two different plant species.
Refer to variables that should be controlled to produce a valid comparison.

Answer 2

Number of shoot tips
Size of agar
Same temperature
Same volume of O2
Increase IAA conc and repeat experiment and calculate mean
Compare and read degree of curvature to determine IAA conc

Question 3

4.3 Grey body and long wings - 233
Black body and short wings - 218
Explain these results

Answer 3

Two genes are linked (autosomal linkage)
No crossing over as they are close together
No gametes produced

Question 4

5.3 Explain why glucose is found in the urine of a person with untreated diabetes

Answer 4

High conc of glucose in blood
Not all glucose is reabsorbed at the proximal convoluted tubule
Carries proteins working at the maximum rate

Question 5

6.3 The control patients were treated with conventional drugs

Answer 5

Effect of AZA can be compared
Unethical to not treat control