Key Area 8 - Photosynthesis
Exercise 9
1. Groups of students carried out an investigation into the effects of
competition.
Trays containing seeds were set up as shown below.
The trays were watered regularly to allow germination to take place.
After several days the seedlings were observed and the number with healthy
green leaves was noted.
The results are shown in the table below.
Number of seeds in
each tray
(i)
Number of
Percentage of
seedlings with
seedlings with
healthy green leaves healthy green leaves
15
12
80
30
18
60
45
23
51
60
24
40
Predict the percentage of seedlings with healthy green leaves if
75 seeds were sown in a seed tray.
1
(ii)
State two factors for which the seedlings could be competing in
this investigation.
1
2. (a) An experiment was set up to measure the effect of light intensity on the
rate of photosynthesis in the water plant. Elodea.
The light intensity was varied using a dimmer switch on the bulb.
The rate of photosynthesis was measured by counting the number
of bubbles released per minute.
(a)
(i)
Name the gas collected.
1
(ii)
The results of the experiment are shown in the table below.
Light intensity
(units)
Rate of photosynthesis
(number of bubbles per minute)
1
2
3
10
5
23
8
45
10
45
12
45
On a grid, plot a line graph to show rate of photosynthesis against
light intensity.
2
(b) Using the data in the table, explain the results obtained at light
intensities greater than 8 units.
1
3. (a) There are two reactions in photosynthesis. The first reaction is
photolysis.
(i)
Name the two substances produced by photolysis that are
required for the second reaction.
1
(ii)
Name the second reaction.
1
(b) Plant cells convert glucose into other carbohydrates.
Copy and complete the table below by naming two of these
carbohydrates.
Role of carbohydrate
in plant cells
2
Name of carbohydrate
Storage as an insoluble material
Forms cell walls
4.
The rate of photosynthesis is limited by certain environmental factors.
Name two limiting factors and describe how the growth of greenhouse plants in
winter can be increased.
3
Items 5 and 6 refer to the accompanying diagram which shows some of the
steps carried out to test a leaf for the presence of starch.
5. The correct sequence of the steps is
A
Y, W, Z, X
B
Z, W, Y, X
C
Y, W, X, Z
1
D
Z, Y, W, X
6. The reason for carrying
out step W is to
A kill the leaf cells
1
1
B soften the leaf discs
C remove chlorophyll from
the leaf cells
D extract oxygen bubbles
from the leaf discs
Items 7 and 8 refer to the accompanying diagram. The plant was left in sunlight
for two days and then leaf discs W, X, Y and Z were tested for the presence of
starch.
7. The leaf disc found to contain starch was
A W
B X
C Y
D Z
1
8. This experiment proves that in order to photosynthesise, a plant must have
A
B
C
D
sunlight and carbon dioxide
carbon dioxide and water
chlorophyll and sunlight
carbon dioxide and chlorophyll
1
9. A variegated leaf on a destarched ivy plant was treated as shown in the
accompanying diagram.
Which of the following shows the appearance of the leaf after testing it for
starch?
10. The total volume of carbon dioxide daily entering the plant shown in the
accompanying diagram is 24 000 mm3.
The daily rate of diffusion of carbon dioxide into the plant in mm3 CO2 per
mm2 of leaf is
A 0.16
1
1
B 6.00
C 48.00
D 3000.00
Questions 11 and 12 refer to the accompanying diagram which shows the process
of photolysis. The two questions also refer to the following possible answers.
A
B
C
D
water
oxygen
hydrogen
carbon dioxide
1
11. What is the correct identity of
chemical substance X?
1
12. What is the correct identity of
chemical substance Y?
1
13. Which of the following CANNOT be used to measure rate of
photosynthesis?
1
A
B
C
D
volume of oxygen released per unit time
volume of carbon dioxide taken up per unit time
mass of carbohydrate produce per unit time
volume of water vapour released per unit time
14. The graph in the accompanying diagram shows the
results from a photosynthesis experiment.
1
Which of the following pairs of environmental factors
must be kept constant during this experiment to make
it valid?
A
B
C
D
light intensity and temperature
Temperature and carbon dioxide concentration
water content and oxygen concentration
light intensity and carbon dioxide concentration
(24)
Exercise 10
1. Products of the photolysis stage of photosynthesis are
2.
A
glucose and hydrogen
B
carbon dioxide and hydrogen
C
water and oxygen
D
hydrogen and oxygen
1
Which of the following are all limiting factors in photosynthesis?
A
Carbon dioxide concentration, temperature and light intensity.
B
Carbon dioxide concentration, oxygen concentration and light
intensity.
C
Oxygen concentration, temperature and light intensity.
D
Oxygen concentration, carbon dioxide concentration and
temperature.
3.
Which line in the table below identifies the best conditions for the
production of early crops?
1
1
4.
5.
What must be present in leaf cells for photosynthesis to take place?
A
carbon dioxide and water
B
oxygen and water
C
carbon dioxide and oxygen
D
oxygen and hydrogen
1
The word equation for photosynthesis is
A
carbon dioxide + water  glucose + oxygen
B
oxygen + water  glucose + carbon dioxide
C
glucose + oxygen carbon dioxide + water
D
dioxide +
glucose +
6.
Plants
mainly for
Added factor
Light intensity
A
oxygen
high
B
oxygen
medium
C
carbon dioxide
medium
D
carbon dioxide
high
A
1
carbon
oxygen 
water
compete
water,
light and soil nutrients
B
water, food and soil nutrients
C
light, water and food
D
light, food and soil nutrients
1
7.
ATP synthesised during photolysis provides the carbon fixation stage of
photosynthesis with
8.
A
glucose
B
carbon dioxide
C
energy
D
hydrogen
1
Photolysis is the
A
combining of water with carbon dioxide
B
use of water by chlorophyll to split light
C
release of energy from water using light energy
D
splitting of water using light energy
1
9.
The table below shows the rate of photosynthesis by a plant measured at
different light intensities.
Light intensity
(kilolux)
Rate of photosynthesis
(units)
10
2
20
27
30
51
40
73
50
82
What change in light intensity produces the greatest increase in the rate
of photosynthesis?
An increase in light intensity from
A
10 to 20 kilolux
B
20 to 30 kilolux
C
30 to 40 kilolux
D
40 to 50 kilolux
1
10.
The bar chart below shows the number of cells of different lengths in a
sample of onion epidermis.
Number
of cells
Length of cell (micrometres)
The percentage of cells with a length greater than 55 micrometres is
11..
A
10%
B
15%
C
20%
D
30%
1
The diagram below shows an investigation into photosynthesis.
Which of the following statements is correct?
12.
A
P, Q and R make food
B
only P and Q make food
C
only P makes
D
only R makes food
1
The diagram below shows the carbon fixation stage of photosynthesis.
ATP
X
carbon dioxide
Which
table
identifies X
Y
glucose
X
Y
A
hydrogen
starch
B
starch
ADP
C
starch
oxygen
D
water
starch
1
line in the
correctly
and Y?
13.
The graph below shows the effect of increasing light intensity on the
rate of photosynthesis.
Rate of
photosynthesis
(bubbles of
oxygen
released
per minute)
Light intensity (units)
Which factor is limiting the rate of photosynthesis at point X on the
graph?
A
carbon dioxide concentration
B
temperature
C
light intensity
D
oxygen concentration
1
14.
The graph below shows the effect of temperature on the rate of
photosynthesis in a plant.
Rate of
photosynthesis
10
o
Temperature ( C)
15
A correct conclusion would be that
15.
A
as the temperature increases, the rate of photosynthesis
increases
B
as the temperature increases, the rate of photosynthesis
decreases
C
as the temperature increases, the rate of photosynthesis
remains constant
D
as the temperature decreases, the rate of photosynthesis
increases
The following stages occur during photosynthesis.
W
X
Y
Z
glucose is formed
water is broken down to produce hydrogen
glucose is converted to starch
hydrogen is combined with carbon dioxide
The correct order for these stages is
A
W Z X Y
B
Z Y X W
1
C
X Z W Y
D
Y X Z W
1
16.
An experiment was carried out to investigate the growth of pea plants
kept in a high light intensity following germination.
The graph shows the average shoot length of the pea plants.
During which 5 day period is there the greatest increase in average shoot
length?
A
Day 10 – 15
B
Day 15 – 20
C
Day 20 – 25
D
Day 25 – 30
1
17.
The diagram below shows the internal structure of a leaf.
During the hours of daylight, the concentration of carbon dioxide in the air
spaces is higher than in the cells of layer X.
Explain why this difference in concentration is important to the leaf cells.
3
18.
The rates of photosynthesis and respiration in a green plant were
measured over a period of 24 hours.
The results are shown in the graph below.
Key
photosynthesis
respiration
(a)
At what time was the production of glucose at its
maximum?
1
(b)
Between what two times was the plant producing more oxygen than
it was using?
1
(c)
What substance traps the light energy required for
photosynthesis?
1
(d)
The diagram below represents a summary of part of the process of
photosynthesis.
ATP + hydrogen
Reaction
X
Substance Y
Substance Z
glucose
(structural
component of
cell walls?
Name the following:
Reaction X;
Substance Y;
Substance Z
(24)
2
Exercise 11
1. a) Lettuces may be grown in ‘tunnels’ covered in clear polythene as shown in
the diagram below.
Air rich in carbon dioxide can be passed through these tunnels.
Explain how this would make lettuces grow faster.
2
b) The graph below shows how the rate of photosynthesis is affected by
light intensity at different concentrations of carbon dioxide.
1
(i)
What factor was limiting the rate of photosynthesis at points 1 and
2?
2
(ii)
Name one other factor that may limit the rate of photosynthesis.
Sugar concentration
(percentage of dry mass)
2. a) A
Time of day
(hours)
Sample 1
Sample 2
Average
0400
0.42
0.48
0.45
0800
0.58
0.62
0.60
1200
1.46
2.04
1.75
1600
1.57
2.43
2.00
2000
1.05
1.75
1.40
scientist grew some cereal plants in a field.
During the course of the day, she removed 2 plants every 4 hours and
measured the concentrations of sugar in the leaves of the plants.
The results are shown in the table below.
2400
0.49
0.51
0.50
Present the results in an appropriate format on a grid.
(b)
(3)
The following word equation shows the first stage of photosynthesis.
light energy
water
oxygen + hydrogen + ATP
(i)
Name this stage of photosynthesis.
(ii)
Describe what happens to each of the following products.
1
(a)
(b)
(c)
Oxygen
1
Hydrogen
1
ATP
1
3. (a) Some students were asked to design an investigation to
compare the rate of production of oxygen gas by two different species of
water plant.
The diagrams below show the proposed procedure.
Identify two changes to the procedure that should be made to ensure that a
valid conclusion can be made.
2
(b)
When changes were made to ensure validity, the following results
were obtained.
Plant
Total volume of
oxygen produced
in8 minutes (cm3)
Rate of oxygen
production
(cm3/minute)
P
64
8
Q
96
(i)
Calculate the rate of oxygen production for Plant Q.
1
(ii)
Calculate the ratio of oxygen produced by Plant P to that
produced by Plant Q.
1
(c)
The volume of oxygen produced was measured at time intervals of
one minute.
The results for Plant Q are shown in the line graph below.
Describe what happens to the volume of oxygen produced per minute as the
investigation proceeds.
1
(d)
The diagram below shows the first stage of photosynthesis.
light energy
Stage 1
water
hydrogen
(i)
Stage 1.
(ii)
oxygen
Name the substance which captures the light energy needed at
1
The energy is used to split water molecules.
1
What name is given to this process?
(iii)
1
The hydrogen the combines with carbon dioxide to form glucose.
Name this second stage in photosynthesis.
1
4. (a) A horticulturist grew a crop of peas in a polythene tunnel.
State two conditions that could limit the rate of
photosynthesis in the pea plants.
(b) The graph below shows the mass of sugar in the leaves and the
concentration of carbon dioxide just above the pea plants at different times of
the day.
concentration of carbon dioxide above the leaves
mass of sugar in the leaves
2
(i)
For how many hours did the carbon dioxide concentration decrease
(ii)
Explain this decrease in carbon dioxide concentration.
1
(iii)
Explain why the mass of sugar in the leaves is as its maximum at
1600.
(iv)
Calculate the percentage increase in sugar in the leaves
between 0400 and 1600.
(v)
Give two reasons why the mass of sugar decreases between
2000 and 0000.
1
1
1
5. Groups of students carried out an investigation into the effects of
competition.
Trays containing seeds were set up as shown below.
The trays were watered regularly to allow germination to take place.
After several days the seedlings were observed and the number with healthy
green leaves was noted.
The results are shown in the table below.
Number of seeds in
each tray
Number of
Percentage of
seedlings with
seedlings with
healthy green leaves healthy green leaves
15
12
80
30
18
60
45
23
51
60
24
40
(i)
Predict the percentage of seedlings with healthy green leaves if 75
seeds were sown in a seed tray.
1
(ii)
State two factors for which the seedlings could be competing in
this investigation.
1
6. Groups of students carried out an investigation into the effects of
competition.
Trays containing seeds were set up as shown below.
The trays were watered regularly to allow germination to take place.
After several days the seedlings were observed and the number with healthy
green leaves was noted.
The results are shown in the table below.
Number of seeds in
each tray
Number of
Percentage of
seedlings with
seedlings with
healthy green leaves healthy green leaves
15
12
80
30
18
60
45
23
51
60
24
40
(i)
Predict the percentage of seedlings with healthy green leaves if 75
seeds were sown in a seed tray.
1
(ii)
State two factors for which the seedlings could be competing in
this investigation.
1
(30)