Fig. 2.1 shows the main stages of the Calvin cycle.
(a) State precisely where the Calvin cycle occurs in plant cells.
[1]
(b) Describe how carbon dioxide is fixed in the Calvin cycle.
[2]
(c) Explain how the products of photophosphorylation are used in the Calvin cycle.
[3]
(d) Explain what initially happens to the concentration of RuBP and GP if the supply of
carbon dioxide is reduced.
RuBP
GP
[2]
[Total: 8]
UCLES 2007 9700/4/SP07 final
PPMMTT
Question
Biology
CAIE2023
(a) Beer contains ethanol. Suggest and explain the role of yeast enzymes in beer
production.
[3]
(b) Most beers contain starch. Recently, ‘light’ beers of low energy content have become
more popular. Light beers have a low starch content. This is achieved by the addition
of immobilised fungal amylase after the mashing process.
(i) Explain the advantage of using immobilised enzymes in this process.
[3]
(ii) The effect of two different types of immobilised fungal amylase on the hydrolysis of
starch is shown in Table 6.1. In these reactions, starch is not a limiting factor.
Table 6.1
mass of maltose produced/g
time/h
α amylase β amylase
Question
Biology
CAIE2023
0.60 0.20
With reference to Table 6.1, explain which of these enzymes would be used in the
production of light beers with a low starch content.
[2]
[Total: 8]
UCLES 2007 9700/4/SP07 final
PPMMTT
Question
Biology
CAIE2023
In the future, climate change may reduce water availability and increase atmospheric
CO concentrations in some habitats.
(a) The respiratory quotient (RQ) values for different respiratory substrates can be calculated.
Table 5.1 shows:
• the formulae of four respiratory substrates
• the number of oxygen molecules (O ) needed to completely respire each substrate to
Question
Biology
CAIE2023
carbon dioxide and water.
Table 5.1
respiratory substrate formula number of oxygen molecules
needed for respiration
beta-hydroxybutyric acid C H O 4.5
Question
Biology
CAIE2023
For
Examiner's
Use
Question
Biology
CAIE2023
[2]
[Total: 8]
UCLES 2007 9700/4/SP07 final [Turn over
PPMMTT
Question
Biology
CAIE2023
0.20 0.10
Question
Biology
CAIE2023
cross pollination
Question
Biology
CAIE2023
[4]
[Total: 8]
UCLES 2007 9700/4/SP07 final [Turn over
PPMMTT
................................................................................................................................................
............................................................................................................................................. [2]
(c) Scientists investigated the response of stomata to changing carbon dioxide (CO )
Question
Biology
CAIE2023
concentrations in the beach morning glory, I. pes-caprae.
The scientists placed I. pes-caprae plants in chambers. They measured the width of
open stomata (stomatal apertures) after the plants had been exposed to different CO
Question
Biology
CAIE2023
concentrations for 40 minutes. Light intensity and temperature were kept constant.
The relationship between CO concentration and the mean width of stomatal apertures is
(a) The respiratory quotient (RQ) values for different respiratory substrates can be calculated.
Table 5.1 shows:
• the formulae of four respiratory substrates
• the number of oxygen molecules (O ) needed to completely respire each substrate to
Question
Biology
CAIE2023
carbon dioxide and water.
Table 5.1
respiratory substrate formula number of oxygen molecules
needed for respiration
beta-hydroxybutyric acid C H O 4.5