BIOLOGY 0610/31
Paper 3 Extended October/November 2008
1 hour 15 minutes
Q1 (iii) Explain how, during a marathon race, the blood glucose concentration
stays fairly
constant, but the mass of glycogen in the liver decreases.[2]
Q2 During a fast race (a 100 metre sprint), 95% of the energy comes from
anaerobic
respiration. During a marathon, only 2% of the energy comes from anaerobic
respiration.
(i) State the equation, in symbols, for anaerobic respiration in muscles.[2]
(ii) Suggest and explain why a sprinter can use mainly anaerobic respiration
during
the race, while a marathon runner needs to use aerobic respiration. [4]
Q3 [SCAN] A student investigated the effect of temperature on the rate of
respiration of maggots. This was measured by calculating the rate of oxygen
uptake, using a respirometer. The apparatus was set up as shown in the diagram
below.
A
i Name a suitable chemical to be used at X. (I)
ii Explain the purpose of chemical X. (I)
The apparatus was placed in a water bath at 25 °C with the clip
open. After 10 minutes the clip was closed and the position of the
liquid in the capillary tube was recorded at 5 minute intervals. The
results obtained are shown in the diagram below.
B
Explain
i why the apparatus was left for 10 minutes before closing the clip
(2)
ii why the liquid moved after the clip was closed. (I) The capillary
tube had a cross-sectional area of 2.5 mm2. c Calculate the rate
of oxygen uptake, in mm3 per minute, between 20 and 30
minutes. Show your working. (2)
d Explain how the results would be expected to differ if the
investigation was carried out at I 5 °C. (2)
Another student carried out the same investigation under exactly
the same conditions, except that a different mass of maggots was
used. e Explain what the students needed to do in order to be
able to compare their results. (I)
Q4 [SCAN] David carried out an investigation into the effect of temperature on
anaerobic respiration in yeast. The only factor that he changed was the
temperature of the reaction mixture.
He was careful to control all other key factors that might affect the rate of
respiration in yeast. David predicted that the rate of respiration in yeast would
increase as the temperature increased. The apparatus he used is shown in the
diagram.
David counted the bubbles of carbon dioxide being given off in one minute as the
yeast respired.
He did this three times for each temperature he used.
a) Why did David put oil on the surface of the yeast and glucose solution?
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b) State one key factor that David should control and suggest how he might do
this. Factor:……………………………………………………………………………
How controlled:………………………………………………………………….
[2]
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c) David put his results into a table.
i) Calculate the average number of bubbles released in one minute at 40 °C. Write
your answer in the empty box in the results table.
[I]
ii) Using the results in the table, describe the effect of increasing the temperature
on the rate of respiration in yeast.
[2]
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iii) David had predicted that the rate of respiration in yeast would increase as the
temperature increased.To what extent do his results support this prediction?
[2]
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iv) Using your biological knowledge, explain the average result at 80 °C.
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d) Identify one anomalous (unexpected) result in David’s table.
[I]
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e) i) Suggest one way that this experiment could be modified to improve the
reliability or accuracy of the results. Explain how your modification could improve
the results. [2]
Modification…………………………………………………………………………………
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Explanation
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ii) Suggest a further experiment David could carry out and explain how it
would provide more information on the effect of temperature on respiration
in yeast
[2]
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[Total 15 marks]
D Describe how you could compare the population size of a plant
growing in two different places. One place is on the side of a hill and the
other place is on a piece of flat ground.