Chloroplasts contain chlorophyll a and chlorophyll b. Scientists found tobacco plants with a
1 mutation that caused them to make more chlorophyll b than normal tobacco plants. They
investigated the effect of this mutation on the rate of photosynthesis.
The scientists carried out the following investigation.
• They grew normal and mutant tobacco plants. They grew some of each in low light intensity
and grew others in high light intensity.
• They isolated samples of chloroplasts from mature plants of both types.
• Finally, they measured oxygen production by the chloroplasts they had isolated from the
plants.
The figure below shows the scientists’ results.
Light intensity / μmol photons m-2s-1
(a) Explain why the scientists measured the rate of production of oxygen in this investigation.
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Page 2 of 133
, In each trial, the scientists collected oxygen for 15 minutes.
(b) Calculate the difference in the oxygen produced by the chloroplasts from mutant plants
grown in low and high light intensities at a light intensity of 500 μmol photons m–2 s–1.
Show your working.
Difference .................................................................... μmol O2 mg–1 hour–1
(2)
(c) The scientists suggested that mutant plants producing more chlorophyll b would grow
faster than normal plants in all light intensities.
Explain how these data support this suggestion.
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(4)
(Total 8 marks)
Page 3 of 133
, Farmland previously used for growing crops was left for 30 years and developed into woodland.
2 During this period, ecologists recorded an increase in the diversity of birds in the area.
(a) Name the process that resulted in the development of woodland from farmland.
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(1)
(b) Explain the increase in the diversity of birds as the woodland developed.
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Page 4 of 133
, (c) The ecologists also investigated photosynthesis in two species of plant found in the
woodland. One of the species was adapted to growing in bright sunlight (sun plant) and the
other was adapted to growing in the shade (shade plant). The ecologists’ results are shown
in the figure below.
(i) Give two factors which could be limiting the rate of photosynthesis in the sun plant
between points A and B on the figure.
1..............................................................................................................
2.............................................................................................................
(1)
(ii) Explain why CO2 uptake is a measure of net productivity.
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(Extra space) ........................................................................................
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(1)
Page 5 of 133
1 mutation that caused them to make more chlorophyll b than normal tobacco plants. They
investigated the effect of this mutation on the rate of photosynthesis.
The scientists carried out the following investigation.
• They grew normal and mutant tobacco plants. They grew some of each in low light intensity
and grew others in high light intensity.
• They isolated samples of chloroplasts from mature plants of both types.
• Finally, they measured oxygen production by the chloroplasts they had isolated from the
plants.
The figure below shows the scientists’ results.
Light intensity / μmol photons m-2s-1
(a) Explain why the scientists measured the rate of production of oxygen in this investigation.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
Page 2 of 133
, In each trial, the scientists collected oxygen for 15 minutes.
(b) Calculate the difference in the oxygen produced by the chloroplasts from mutant plants
grown in low and high light intensities at a light intensity of 500 μmol photons m–2 s–1.
Show your working.
Difference .................................................................... μmol O2 mg–1 hour–1
(2)
(c) The scientists suggested that mutant plants producing more chlorophyll b would grow
faster than normal plants in all light intensities.
Explain how these data support this suggestion.
........................................................................................................................
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........................................................................................................................
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(Extra space) ................................................................................................
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........................................................................................................................
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(4)
(Total 8 marks)
Page 3 of 133
, Farmland previously used for growing crops was left for 30 years and developed into woodland.
2 During this period, ecologists recorded an increase in the diversity of birds in the area.
(a) Name the process that resulted in the development of woodland from farmland.
........................................................................................................................
(1)
(b) Explain the increase in the diversity of birds as the woodland developed.
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........................................................................................................................
........................................................................................................................
(Extra space) .................................................................................................
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(3)
Page 4 of 133
, (c) The ecologists also investigated photosynthesis in two species of plant found in the
woodland. One of the species was adapted to growing in bright sunlight (sun plant) and the
other was adapted to growing in the shade (shade plant). The ecologists’ results are shown
in the figure below.
(i) Give two factors which could be limiting the rate of photosynthesis in the sun plant
between points A and B on the figure.
1..............................................................................................................
2.............................................................................................................
(1)
(ii) Explain why CO2 uptake is a measure of net productivity.
...............................................................................................................
...............................................................................................................
(Extra space) ........................................................................................
...............................................................................................................
(1)
Page 5 of 133
