PRACTICE EXAM QUESTIONS
1
The figure below shows bubbles of gas coming from the cut stem of an illuminated
inverted shoot of the aquatic plants Elodea.
(a) State three environmental factors, in addition to light intensity, that could affect the
rate of bubble production in Elodea. [3]
(b)Explain briefly how the oxygen in the gas bubbles is produced. [3]
(c)The intensity of the light falling on Elodea is proportional to 1/d 2 (where d is the
distance between the lamp and the inverted shoot).
If a lamp, at 10 cm from the shoot, produces a reading of 20 bubbles per minute, how
many bubbles per minute would you except to count if the lamp is placed at 5 cm from
the shoot? Show your working. [2]
(d)The figure below represents several different components of a thylakoid.
State precisely in which component(s) of a thylakoid, each of the following processes
takes place:
i.
photolysis
ii.
absosrption of light of wavelength 680 nm
iii.
cyclic photophosphorylation
iv.
non-cyclic photophosphorylation
v.
the reduction of NADP+ to NADPH. [5]
(b) What is a proton pump and what is its role in photosynthesis? [3]
2 Calvin investigated the pathway by
which carbon dioxide is converted to
organic compounds during photosynthesis.
He used the apparatus shown in the diagram.
The apparatus contained cells of a unicellular alga.
While the apparatus was in a dark room,
Calvin supplied the algal cells with carbon dioxide
containing radioactive carbon. The contents of the
apparatus were thoroughly mixed, then a light
was switched on. At five-second intervals
he released a few of the cells into hot
alcohol,which killed the cells very quickly.
(a) Suggest
i.
Why the part of the apparatus containing the algal cells is thin;
ii.
How it would be possible to prevent the light source from heating the
algal cells;
iii.
Why it was necessary for the algal cells to be killed very quickly.
Calvin homogenised the killed algal cells and carried out two-way paper
chromatography. This technique involves running the chromatogram with one
solvent, then turning the paper through 90 o and running it with a different
solvent.
By using this technique, Calvin was able to investigate the organic compounds
produced during photosynthesis. The diagram shows the chromatograms he
obtained. The spots are those containing radioactive compounds.
(b) Suggest how the compound present in each spot on the chromatogram might
be identified. [1]
(c) i.
Name the compound first formed in the pathway in which carbon dioxide
is converted to an organic compound. [1]
ii.
Which of the spots, W, X, Y, or Z contained this compound? [1]
iii.
Explain your answer to c ii. [1]
3
(a) Describe how the structure and distribution of chloroplasts ensures the efficient
trapping of light by leaves. [10]
(b) The synthesis of ATP is driven by a flow of protons. Describe where and how
the required proton gradient is produced in the chloroplast. [10]
4
The graph bellows shows how the wavelength of light affects the rate of
photosynthesis.
(a) i.
What name is given to the relationship between wavelength of light and
the rate
of photosynthesis, as shown by this graph? [1]
ii.
From the graph, state the optimum wavelength of light for
photosynthesis. [1]
iii.
Explain the effect on the rate of photosynthesis of varying the wavelength
of light
from 550 to 700 nm. [2]
(b) i.
Name the stage of photosynthesis that produces oxygen. [1]
ii.
State where in a chloroplast this stage would occur. [1]
5
(a) The diagram summaries the light-independent reaction of photosynthesis.
i.Copy and complete the four boxes to show the number of carbon atoms in a
molecule of each substance. [1]
ii.
Where in the chloroplast does the light-independent reactions take
place?[1]
iii.
Explain why the amount of GP increases after a photosynthesising plant
has been in darkness for a short time. [2]
(b) Describe the role of water in the light-dependent reaction of photosynthesis.
[2]
FREE RESPONE QUESTIONS
1
Describe the adaptations of a leaf in a dicotyledonous plant for efficient
photosynthesis. [6]
2
State the similarities in, and the differences between, the structures of chloroplast
and mitochondrion. [10]
3
Describe the roles in photosynthesis of the various pigment in the chloroplast. [6]
4
Describe the role of light in photosynhesis. [8]
5
Explain the importance of the light-dependent reaction in photosynthesis. [7]
6
Describe how sunlight energy is converted to chemical energy in green plants. [10]
7
Distinguish between photophosphorylation and oxidative
indicating the important features of each process. [13]
8
Explain the main stages of the Calvin cycle. [8]
9
Outline the steps involved in the uptake of a carbon dioxide molecule from the
atmosphere and its incorporation into a sugar molecule. [13]
10
Explain how the used of isotopes has contributed to our understanding of the
process of photosynthesis. [9]
11
Explain how (a) sunlight energy (b) carbon dioxide from the air pass to, and are
used by, the chloroplast during photosynthesis. [15]
Suggest how productivity may be increased in glasshouse crops. [3]
12
phosphorylation,