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1 (a) Name two pigment molecules found in chloroplasts.
(b) Explain the role of pigment molecules.
(a) Describe the effects of different wavelengths of light on the rate of
(b) Pigments are present in photosystems I and II. Where are the photosystems
located in the chloroplasts and how…

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Name the enzyme that fixes carbon dioxide.
(c) What is the role of reduced NADP in the cycle?
(d) What is the name of the cycle?
(e) Where in the chloroplast does the cycle occur?

4 During the lightindependent stage of photosynthesis, six molecules of carbon
dioxide combine with six…

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The rate of photosynthesis is limited by a number of factors. The figure below
shows the effects of light intensity at different carbon dioxide concentrations and

(a) What limits the rate of photosynthesis at low light intensities?
(b) Why is there no further increase in the rate at high…

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The diagram below summarizes the movement of materials within chloroplasts
and between them and the cytoplasm. Identify substances (a) to (e) from the
diagram that follows.

8 The volume of oxygen released by an aquatic plant was calculated in mm3 h­1 for
two different light intensities at different temperatures. The…

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Light intensity is inversely proportional to the square of the distance from the
source: if the distance is increased by a factor of 2 the intensity falls by a
factor of 1/2 = 1/4 or 25%. This is called the inverse square law.
Leaf discs extracted from young spinach…

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Answers to questions
1 (a) Chlorophyll a, chlorophyll b, carotene,
xanthophylls, phaeophytin.
(b) To absorb certain wavelengths of light, exciting electrons for use in the lightdependent stage of photosynthesis.
(c) Wavelengths of about 400­450 nm (blue) and
650­700 nm (red) give high rates of photosynthesis but wavelengths of…

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(e) Because carbon dioxide from respiration is being used in photosynthesis, so no carbon dioxide is taken up ­ or
because oxygen from photosynthesis is being used in respiration, so no oxygen is released.
6 (a) By dissolving lipids and denaturing proteins the
hot alcohol prevented further reactions. Thus, at…

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(a) H2O.
(b) O2 .
(c) ATP (or NADPred).
(d) NADPred (or ATP).
(e) CO2.
8 (a) (i) The rate barely increases from about 1.0 mm3
h­1 to 1.5 mm3 h­1 with a rise in temperature and declines after 30 °C.
(ii) The rate increases with temperature,
approximately doubling for…

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of pyruvate), having a very high affinity for carbon dioxide these plants are at an advantage in competing with other
plants for the small amount of carbon dioxide, which, given that other conditions are favourable, would otherwise
be limiting.


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