Q1.
(a) Starch and protein are biologically important polymers.
(i) Explain what is meant by a polymer.
______________________________________________________________
______________________________________________________________
(1)
(ii) Give one example of a biologically important polymer other than starch or
protein.
______________________________________________________________
(1)
(b) In an investigation, the enzyme amylase was mixed in a test tube with a buffer
solution and a suspension of starch. The amylase broke down the starch to maltose.
When all the starch had been broken down, a sample was removed from the test
tube and tested with biuret reagent.
(i) Explain why a buffer solution was added to the amylase-starch mixture.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(ii) What colour would you expect the sample to go when tested with biuret
reagent?
______________________________________________________________
(1)
(iii) Give an explanation for your answer to part (ii)
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(Total 7 marks)
Q2.
The diagram shows a cell from a potato.
Page 1 of 23
, (a) Give two features which may be found in a prokaryotic cell which would not be
found in this cell.
1. _________________________________________________________________
2. _________________________________________________________________
(2)
(b) (i) Describe how you could confirm that the granules contained starch.
______________________________________________________________
______________________________________________________________
(1)
______________________________________________________________
(ii) Name one polysaccharide other than starch that would be found in this cell.
______________________________________________________________
(1)
(c) Explain one advantage of storing starch rather than glucose in potato cells.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(Total 6 marks)
Q3.
In an investigation, the effects of caffeine on performance during exercise were measured.
One group of athletes (A) was given a drink of decaffeinated coffee. Another group (B)
was given a drink of decaffeinated coffee with caffeine added. One hour later the athletes
started riding an exercise bike and continued until too exhausted to carry on. Three days
later the same athletes repeated the experiment, with the drinks exchanged.
(a) (i) The researchers added caffeine to decaffeinated coffee. Explain why
Page 2 of 23
, they did not just use normal coffee.
______________________________________________________________
______________________________________________________________
(1)
(ii) The performance of the athletes might have been influenced by how they
expected the caffeine to affect them. How could the researchers avoid this
possibility?
______________________________________________________________
______________________________________________________________
(1)
During the exercise the concentrations of glycerol and fatty acids in the blood plasma
were measured. The results are shown in the table.
Drink Mean time to Mean Mean
exhaustion concentration of concentration of
/minutes blood glycerol/ blood fatty
mmol dm–3 acids/
mmol dm–3
With caffeine 90.2 0.20 0.53
Without caffeine 75.5 0.09 0.31
(b) (i) Describe the effect of caffeine on exercise performance.
______________________________________________________________
______________________________________________________________
(1)
(ii) Suggest one explanation for the higher glycerol and fatty acid
concentrations in the blood plasma of the athletes after they were given
caffeine.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(c) The researchers measured the volumes of carbon dioxide exhaled and oxygen
inhaled during the exercise. From the results they calculated the respiratory quotient
(RQ), using the formula
Page 3 of 23
(a) Starch and protein are biologically important polymers.
(i) Explain what is meant by a polymer.
______________________________________________________________
______________________________________________________________
(1)
(ii) Give one example of a biologically important polymer other than starch or
protein.
______________________________________________________________
(1)
(b) In an investigation, the enzyme amylase was mixed in a test tube with a buffer
solution and a suspension of starch. The amylase broke down the starch to maltose.
When all the starch had been broken down, a sample was removed from the test
tube and tested with biuret reagent.
(i) Explain why a buffer solution was added to the amylase-starch mixture.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(ii) What colour would you expect the sample to go when tested with biuret
reagent?
______________________________________________________________
(1)
(iii) Give an explanation for your answer to part (ii)
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(Total 7 marks)
Q2.
The diagram shows a cell from a potato.
Page 1 of 23
, (a) Give two features which may be found in a prokaryotic cell which would not be
found in this cell.
1. _________________________________________________________________
2. _________________________________________________________________
(2)
(b) (i) Describe how you could confirm that the granules contained starch.
______________________________________________________________
______________________________________________________________
(1)
______________________________________________________________
(ii) Name one polysaccharide other than starch that would be found in this cell.
______________________________________________________________
(1)
(c) Explain one advantage of storing starch rather than glucose in potato cells.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(Total 6 marks)
Q3.
In an investigation, the effects of caffeine on performance during exercise were measured.
One group of athletes (A) was given a drink of decaffeinated coffee. Another group (B)
was given a drink of decaffeinated coffee with caffeine added. One hour later the athletes
started riding an exercise bike and continued until too exhausted to carry on. Three days
later the same athletes repeated the experiment, with the drinks exchanged.
(a) (i) The researchers added caffeine to decaffeinated coffee. Explain why
Page 2 of 23
, they did not just use normal coffee.
______________________________________________________________
______________________________________________________________
(1)
(ii) The performance of the athletes might have been influenced by how they
expected the caffeine to affect them. How could the researchers avoid this
possibility?
______________________________________________________________
______________________________________________________________
(1)
During the exercise the concentrations of glycerol and fatty acids in the blood plasma
were measured. The results are shown in the table.
Drink Mean time to Mean Mean
exhaustion concentration of concentration of
/minutes blood glycerol/ blood fatty
mmol dm–3 acids/
mmol dm–3
With caffeine 90.2 0.20 0.53
Without caffeine 75.5 0.09 0.31
(b) (i) Describe the effect of caffeine on exercise performance.
______________________________________________________________
______________________________________________________________
(1)
(ii) Suggest one explanation for the higher glycerol and fatty acid
concentrations in the blood plasma of the athletes after they were given
caffeine.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(c) The researchers measured the volumes of carbon dioxide exhaled and oxygen
inhaled during the exercise. From the results they calculated the respiratory quotient
(RQ), using the formula
Page 3 of 23
