Photosynthesis Question Booklet
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Unit 4- Woodford County High School
1.
(a)
Give two reasons why much of the sunlight falling on the leaves of a plant grown
in a glasshouse is not used in photosynthesis.
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(2)
(b)
What measurements could be taken in order to find the rate of photosynthesis?
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(2)
(c)
Outline how you would investigate the effect of temperature on the yield of a crop
of plants grown in a glasshouse.
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(3)
(Total 7 marks)
Unit 4- Woodford County High School
2.
An investigation was carried out to find out the sequence of biochemical changes that
occur during photosynthesis. Radioactive carbon dioxide was added to a suspension of
algal cells, and they were allowed to photosynthesise. At intervals, samples of the
suspension were removed into hot alcohol. These samples were analysed for different
radioactively labelled compounds.
Suspension of
algal cells
Light
Syringe for
injecting
radioactive
carbon
dioxide
Rapid
action
tap
Hot
alcohol
(a)
Explain how the use of radioactive carbon dioxide in this investigation allows the
sequence of biochemical changes in photosynthesis to be followed.
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(2)
(b)
Suggest a reason for the use in this investigation of
(i)
hot alcohol;
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(1)
Unit 4- Woodford County High School
(ii)
a rapid action tap.
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(1)
Samples were removed from the suspension at five different times, between 5 seconds
and 600 seconds after the start of the experiment. In each sample, the radioactivity in
four different organic compounds, P, Q, R and S, was measured. The table shows the
results.
(c)
Amount of radioactivity present / arbitrary units
Organic
compound
5s
15 s
60 s
180 s
600 s
P
0.01
0.02
0.08
0.17
0.67
Q
1.00
2.00
3.10
3.15
3.15
R
0.10
1.50
2.20
2.30
2.40
S
0.05
0.11
0.16
1.00
1.00
Use this information to place the compounds P, Q, R and S, in the order in which
they were formed in photosynthesis.
_____________  _____________  _____________  _____________
(1)
(d)
Using your knowledge of the light-independent reaction, explain why the level of
radioactivity in compound Q remained steady after 180 seconds.
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(2)
(Total 7 marks)
Unit 4- Woodford County High School
3.
The diagram shows a cell organelle.
(a)
Identify the parts labelled X and Y.
X ................................................................................................................................
Y ................................................................................................................................
(2)
Light was shone on a suspension of these organelles while it was kept in an atmosphere
of pure nitrogen. During this time the organelles made large amounts of two different
substances, and gave off oxygen.
(b)
Name the two substances that were made when the organelles were illuminated.
1 ..................................................................................................................................
2 ..................................................................................................................................
(2)
The membranes around the outside of the organelles were then broken, and the parts
labelled X and Y were separated from each other. In the dark, part Y was supplied with a
substance, which it converted into a carbohydrate.
(c)
What is the name of the substance which was converted into a carbohydrate?
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(1)
(d)
(i)
Name the part of the organelle where the enzymes of the light-independent
reaction are located.
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(1)
(ii)
Use the diagram to give the function of one other enzyme that is present in
this part of the organelle.
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(1)
(Total 7 marks)
Unit 4- Woodford County High School
4.
The percentage of light absorbed by an aquatic plant was measured when it was exposed
to different wavelengths. The rate of photosynthesis was also measured at each
wavelength of light. The results are shown in the graph.
Percentage of
light absorbed
(
)
400
(a)
Rate of
photosynthesis
(
)
500
600
Wavelength of light / nm
700
Describe and explain the relationship between light absorption and the rate of
photosynthesis for the wavelengths of light between 410 nm and 500 nm.
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(2)
Unit 4- Woodford County High School
(b)
Give one dependent variable you could measure in order to determine the rate of
photosynthesis in an aquatic plant.
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(1)
(c)
Use the graph to identify the range of wavelengths of light that would be green in
colour.
Give a reason for your answer.
Wavelengths ................... to ................... nm
Reason ........................................................................................................................
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(2)
(d)
A suspension of chloroplasts was isolated from an aquatic plant and a reagent was
added. The reagent is blue when oxidised and is colourless when reduced.
(i)
The suspension of chloroplasts in blue reagent was exposed to sunlight. The
blue colour disappeared. Use your knowledge of the light-dependent
reactions of photosynthesis to explain why.
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(2)
(ii)
Another suspension of chloroplasts was set up as before. Small quantities of
ADP and phosphate ions were added and then the tube was exposed to light.
The blue colour disappeared more quickly. Explain why.
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(2)
(Total 9 marks)
Unit 4- Woodford County High School
5.
The diagram shows a summary of the light-independent reaction of photosynthesis.
Carbon dioxide
1C
+
Ribulose bisposphate
(RuBP)
...... C
2×
Glycerate 3-phosphate
(GP)
...... C
Reduced
NADP
ATP
Triose phosphate
(a carbohydrate)
...... C
Glucose
...... C
(a)
(i)
Complete the boxes to show the number of carbon atoms in the molecules.
(2)
(ii)
In which part of a chloroplast does the light-independent reaction occur?
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.
(1)
(iii) Which process is the source of the ATP used in the conversion of glycerate
3-phosphate (GP) to triose phosphate?
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.
(1)
(iv)
What proportion of triose phosphate molecules is converted to ribulose
bisphosphate (RuBP)?
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(1)
(b)
Lowering the temperature has very little effect on the light-dependent reaction, but
it slows down the light-independent reaction. Explain why the light-independent
reaction slows down at low temperatures.
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Unit 4- Woodford County High School
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(2)
(Total 7 marks)
6.
The graph shows the absorption of different wavelengths of light by three photosynthetic
pigments in a red seaweed.
Violet Blue Green
Yellow Orange Red
Chlorophyll a
Phycocyanin
Phycoerythrin
Absorbance
400
(a)
(i)
600
500
Wavelength / nm
700
Describe what the graph shows about the properties of chlorophyll a.
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(1)
(ii)
Describe the part played by chlorophyll in photosynthesis.
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(3)
Unit 4- Woodford County High School
(b)
The red seaweed lives under water at a depth of 2 metres. Suggest an advantage to
the red seaweed of having other pigments in addition to chlorophyll a.
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(2)
(Total 6 marks)
7.
(a)
Describe how NADP is reduced in the light-dependent reaction of photosynthesis.
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(2)
(b)
In an investigation of the light-independent reaction, the amounts of glycerate
3-phosphate (GP) and ribulose bisphosphate (RuBP) in photosynthesising cells
were measured under different environmental conditions.
Figure 1 shows the effect of reducing the carbon dioxide concentration on the
amounts of glycerate 3-phosphate and ribulose bisphosphate in photosynthesising
cells.
Figure 1
1.0 % CO2
0.003 % CO 2
2.5
RuBP
2.0
Relative
amounts
1.5
GP
1.0
0.5
0.0
Time
Unit 4- Woodford County High School
(i)
Explain why there is twice the amount of glycerate 3-phosphate as ribulose
bisphosphate when the carbon dioxide concentration is high.
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(1)
(ii)
Explain the rise in the amount of ribulose bisphosphate after the carbon
dioxide concentration is reduced.
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(1)
(c)
Figure 2 shows the results of an experiment in which photosynthesising cells were
kept in the light and then in darkness.
Figure 2
Light
Dark
GP
Amounts
of each
radioactive
substance
Glucose
RuBP
Application
of 14CO2
(i)
Light switched off
Time
In the experiment the cells were supplied with radioactively labelled 14CO2.
Explain why the carbon dioxide used was radioactively labelled.
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(1)
(ii)
Explain how lack of light caused the amount of radioactively labelled
glycerate 3-phosphate to rise.
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Unit 4- Woodford County High School
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(2)
(iii)
Explain what caused the amount of radioactively labelled glucose to
decrease after the light was switched off.
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(1)
(Total 8 marks)
8.
(a)
The process of photosynthesis can be subdivided into two stages, one dependent
on light, the other independent of light.
(i)
Complete the table to show the substances used in and the end products of
each of these stages. (Do not include solar energy.)
Light dependent stage
Substances used
1. Water
2. Inorganic phosphate
3. ADP
4. NADP
Light independent stage
1. Reduced NADP
2. ATP
3. ......................................
4. .......................................
End products
1.ATP
2. ....................................
3. ....................................
1. NADP
2. ADP
3. Inorganic phosphate
4. Carbohydrate
(2)
(ii)
What are the functions of reduced NADP and ATP in the light independent
stage of photosynthesis?
Reduced
NADP..................................................................................................
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ATP...................................................................................................................
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(2)
Unit 4- Woodford County High School
(b)
The graph shows the effect of temperature on the rate of photosynthesis
Rate of
photosynthesis
X
(i)
Y
Z
Temperature /ºC
Explain why increasing the temperature from X° C to Y° C increases the
rate of photosynthesis.
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(2)
(ii)
Explain why increasing the temperature from Y° C to Z° C decreases the
rate of photosynthesis.
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(2)
(Total 8 marks)
Unit 4- Woodford County High School
Mark Scheme
1.
(a)
(b)
(c)
wrong wavelength;
reflected;
miss chloroplast / chlorophyll;
(carbon dioxide concentration) another factor may be limiting;
2
oxygen produced / carbon dioxide used;
per unit time;
2
description of how temperature is changed / range of temperatures used;
how other factors kept the same / named factors controlled;
measure mass of given product in given time;
3
[7]
2.
(a)
(b)
(Radioactive) carbon dioxide is used / incorporated;
New compound(s) / intermediate(s) / names egs formed /
become labelled;
(i)
(ii)
2
Because stops reaction(s)/ process / pathway / enzyme action /
kills algal cells;
1
Because reactions occur quickly
OR need to remove samples after short / precise time;
1

R

S

(c)
Q
P ;
1
(d)
Idea of cycle (or equivalent);
Compound Q is used / reformed;
If either above present allow identification of possible Q as: G3P /
PGA / triose phosphate / GALP / RuBP
Any two from three (noting special arrangement re. third point)
2
[7]
3.
(a)
(b)
X = grana/lamellae/thylakoid (membranes);
Y = stroma;
2
NADPH2/ NADPH/ reduced NADP/reduced coenzyme;
ATP;
2
(c) carbon dioxide/CO2;
(d)
(i)
stroma; NOT “Y”
Unit 4- Woodford County High School
1
1
(ii)
production/breakdown of starch (or equivalent);
1
[7]
4.
(a)
(b)
(c)
(d)
the more light absorbed, the greater the rate of photosynthesis;
light provides the energy for light dependent reactions / photolysis /
light independent reactions / production of reduced NADP /
exciting electrons in chlorophyll;
(do not give credit if energy is used in photosynthesis)
2
count the number of bubbles / measure the volume of gas / measure the
change in pH / carbon dioxide / hydrogen carbonate ions;
(credit oxygen produced)
1
530 – 630 nm; (any values within this range)
limited absorption of light / (green) plants reflect green light /
limited photosynthesis at these wavelengths of light;
(allow references to no light absorbed or no photosynthesis)
(i)
(ii)
chlorophyll excited / reduced NADP formed;
electrons from chlorophyll / reduced NADP changes the dye colour;
ADP and phosphate needed to produce ATP / ATP is a product of
the light dependent reactions;
ADP levels are a limiting factor;
(must explain the idea of limiting factors – do not credit answers
like more ADP causes more photosynthesis)
2
2
2
[9]
5.
(a)
RuBP – 5; GP – 3; TP – 3; Glucose – 6;
(all correct = 2 marks; 3 or 2 correct = 1 mark)
2
(ii)
stroma;
1
(iii)
light-dependent reaction / (photo)phosphorylation;
(accept photolysis)
1
5 out of 6 / 83% / equivalent;
1
(i)
(iv)
(b)
enzymes involved / not a photochemical reaction;
slow rate of enzyme/chemical reaction at low temperature /
less kinetic energy / fewer collisions;
2
[7]
6.
(a)
(i)
pigment reflects/does not absorb green or yellow or orange;
pigment absorbs blue or violet;
pigment absorbs red;
(accept correct wavelengths instead of colours)
Unit 4- Woodford County High School
1
(any 2 for 1 mark)
(ii)
(b)
light (energy) absorbed by chlorophyll;
raises energy level of electrons / electrons are excited/emitted;
ATP formed;
3
more wavelengths / colours absorbed;
more (efficient) photosynthesis can occur at these depths / low light intensities
or
more (efficient) photosynthesis can occur when some wavelengths are not
present;
2
[6]
7.
(a)
(b)
(c)
electrons;
from chlorophyll / photolysis;
2
(i)
RuBP combines with carbon dioxide to produce 2 x GP;
1
(ii)
less used to combine with carbon dioxide /
less used to form glycerate 3-phosphate;
1
(i)
used in photosynthesis allows detection of products;
1
(ii)
ATP and reduced NADP not formed;
GP is not being used to form RuBP / is being formed from RuBP;
2
used in respiration / formation of starch / cellulose;
1
(iii)
[8]
8.
(a)
(i)
2
Light dependent stage
Raw materials
End products
(ii)
(b)
(i)
(ii)
Light independent stage
Carbon dioxide and
ribulose
bisphosphate/ RuBP;
Reduced NADP and
oxygen;
reduced NADP provides the hydrogen to change GP to TP/reduces GP;
ATP provides the energy to resynthesise ribulose bisphosphate/
change / reduce GP /synthesise hexose;
2
kinetic effect / molecules move faster / more kinetic energy;
more collisions;
more enzyme -substrate complex formed /
more binding to active site;
max. 2
breaking of (correct) bonds in enzyme molecule;
shape of active site changed / denaturation;
substrate does not bind / attach to enzyme;
max. 2
[8]
Unit 4- Woodford County High School