Exam (elaborations)
A Level Biology Paper 2 past paper 2023 (EXAM REVISION)
A Level Biology Paper 2 past paper 2023, mark scheme and questions. Mock revision for actual exams
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Exams 2023A-Level Biology Paper 2
201marks
Q1.
(a) In photosynthesis, which chemicals are needed for the light-dependent reaction?
Tick (✓) one box.
Reduced NADP, ADP, Pi, water and oxygen.
NADP, ATP and water.
Reduced NADP, ATP, water and carbon dioxide.
NADP, ADP, Pi and water.
(1)
(b) Describe what happens during photoionization in the light-dependent reaction.
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(2)
A student obtained a solution of pigments from the leaves of a plant. Then the student
used paper chromatography to separate the pigments.
The diagram shows the chromatogram produced.
(c) Explain why the student marked the origin using a pencil rather than using ink.
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(1)
(d) Describe the method the student used to separate the pigments after the solution of
pigments had been applied to the origin.
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(2)
(e) Calculating the Rf values of the pigments can help to identify each pigment. An Rf
value compares the distance the pigment has moved from the origin with the
distance the solvent front has moved from the origin.
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, The distance each pigment has moved is measured from the middle of each spot.
Pigment A has an Rf value of 0.95
Use the diagram above to calculate the Rf value of pigment C.
Rf value of pigment C = _________________________
(1)
(f) The pigments in leaves are different colours. Suggest and explain the advantage of
having different coloured pigments in leaves.
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(1)
(Total 8 marks)
Q2.
Heat stress is a condition that often occurs in plants exposed to high temperatures for a
prolonged period of time. Heat stress is a major factor in limiting the rate of
photosynthesis.
(a) Heat stress decreases the light-dependent reaction of photosynthesis.
Explain why this leads to a decrease in the light-independent reaction.
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(2)
(b) Another effect of heat stress is a decrease in the activity of the enzyme rubisco. A
decrease in the activity of an enzyme means that the rate of the reaction it catalyses
becomes slower.
A decrease in the activity of the enzyme rubisco would limit the rate of
photosynthesis.
Explain why.
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(2)
(c) Where precisely is rubisco found in a cell?
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(1)
Scientists investigated the effect of temperature on the activity of two enzymes isolated
from the leaf cells of cotton plants.
• Rubisco
• Rubisco activase – an enzyme that activates rubisco
Figure 1 and Figure 2 show their results.
(d) The scientists concluded that heat stress reduces the activity of rubisco in plant
leaves by affecting rubisco activase.
Use all the information to evaluate their conclusion.
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