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Q1.
Photosynthesis uses carbon dioxide to make glucose.
(a)     (i)      Complete the equation for photosynthesis.
carbon dioxide + _____________ glucose + _____________
(2)
(ii)     What type of energy does a plant use in photosynthesis?
______________________________________________________________
(1)
(iii)    Which part of a plant cell absorbs the energy needed for photosynthesis?
______________________________________________________________
(1)
(b)     The graph shows the effect of the concentration of carbon dioxide on the rate of photosynthesis in tomato plants at 20 °C.
 
(i)      What is the maximum rate of photosynthesis of the tomato plants shown in the graph?
_____________ arbitrary units
(1)
(ii)     At point X, carbon dioxide is not a limiting factor of photosynthesis.
Suggest one factor that is limiting the rate of photosynthesis at point X.
______________________________________________________________
(1)
(c)     A farmer plans to grow tomatoes in a large greenhouse.
The concentration of carbon dioxide in the atmosphere is 0.04%.
The farmer adds carbon dioxide to the greenhouse so that its concentration is 0.08%.
(i)      Why does the farmer use 0.08% carbon dioxide?
Tick () one box.
 
To increase the rate of growth of the tomato plants |
To increase the rate of respiration of the tomato plants |
To increase water uptake by the tomato plants |
(1)
(ii)    Why does the farmer not use a concentration of carbon dioxide higher than 0.08%?
Tick () two boxes.
 
Because it would cost more money than using 0.08% |
Because it would decrease the temperature of the greenhouse |

Because it would not increase the rate of photosynthesis of the
tomato plants any further

Because it would increase water loss from the tomato plants |
(2)
(Total 9 marks)
Q2.
A student investigated growth in plants.
The student:
•        planted a seed in damp soil in a plant pot
•        put the plant pot in a dark cupboard.
The image below shows the result after 5 days.
 
(a)     Draw a ring around the correct answer to complete each sentence.

(i)

After the 5 days, the root had grown

away from water.
in the direction of the force of gravity.
towards light.

(1)

(ii)

After the 5 days, the shoot had grown

against the force of gravity.
away from light.
towards water.

(1)
(b)     After the plant had grown, the student put the plant pot by a window with lots of light.
The illustration below shows this.
 
(i)      Complete the diagram below to show the appearance of the student’s plant after 20 days by the window.
 
(1)
(ii)     Explain the advantage to the plant of growing in the way that you have drawn in part (b)(i).
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(Total 5 marks)
Q3.
Photosynthesis needs light.
(a)     Complete the balanced symbol equation for photosynthesis.
light
6CO_2 + _______________________  _______________________ + 6O_2
(2)
(b)     A green chemical indicator shows changes in the concentration of carbon dioxide (CO_2) in a solution.
The indicator solution is green when the concentration of CO_2 is normal.
The indicator solution turns yellow when the concentration of CO_2 is high.
The indicator solution turns blue when the concentration of CO_2 is very low or when there is no CO_2.
The indicator solution does not harm aquatic organisms.
Students investigated the balance of respiration and photosynthesis using an aquatic snail and some pondweed.
The students set up four tubes, A, B, C and D, as shown in the table below.
The colour change in each tube, after 24 hours in the light, is recorded.
 
Tube A | Tube B | Tube C | Tube D

Indicator solution
only

Indicator solution
+ pondweed

Indicator solution
+ snail

Indicator solution
+ pondweed
+ snail

Stays green | Turns blue | Turns yellow | Stays green
(i)      What is the purpose of Tube A?
______________________________________________________________
______________________________________________________________
(1)
(ii)     Explain why the indicator solution in Tube C turns yellow.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(iii)    Predict the result for Tube D if it had been placed in the dark for 24 hours and not in the light.
Explain your prediction.
Prediction _____________________________________________________
______________________________________________________________
Explanation ____________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(3)
(Total 8 marks)
Q4.
(a)     Complete the equation for photosynthesis. Draw a ring around each correct answer.
 
| | hydrogen | | alcohol | |
Carbon dioxide | + | nitrogen | light energy | glucose | + | oxygen
| | water | | methane | |
(2)
Some students investigated the effect of light intensity on the rate of photosynthesis in pondweed.
The diagram shows the apparatus the students used.
 
The closer the lamp is to the pondweed, the more light the pondweed receives.
The students placed the lamp at different distances, d, from the pondweed.
They counted the number of bubbles of gas released from the pondweed in 1 minute for each distance.
(b)     A thermometer was placed in the glass beaker.
Why was it important to use a thermometer in this investigation?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(3)
(c)     The students counted the bubbles four times at each distance and calculated the correct mean value of their results.
The table shows the students’ results.

Distance
d in cm

Number of bubbles per minute

| 1 | 2 | 3 | 4 | Mean
10 | 52 | 52 | 54 | 54 | 53
20 | 49 | 51 | 48 | 52 | 50
30 | 32 | 30 | 27 | 31 | 30
40 | 30 | 10 | 9 | 11 |
(i)      Calculate the mean number of bubbles released per minute when the lamp was 40 cm from the pondweed.
______________________________________________________________
______________________________________________________________
Mean number of bubbles at 40 cm = ______________________
(2)
(ii)     On the graph paper below, draw a graph to show the students’ results:
•        add a label to the vertical axis
•        plot the mean values of the number of bubbles
•        draw a line of best fit.
  
                  Distance d in cm
(4)
(iii)    One student concluded that the rate of photosynthesis was inversely proportional to the distance of the lamp from the plant.
Does the data support this conclusion?
Explain your answer.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(d)     Light intensity, temperature and concentration of carbon dioxide are factors that affect the rate of photosynthesis.
Scientists investigated the effects of these three factors on the rate of photosynthesis in tomato plants growing in a greenhouse.
The graph below shows the scientists’ results.
 
Light intensity in lux
A farmer in the UK wants to grow tomatoes commercially in a greenhouse.
The farmer read about the scientists’ investigation.
During the growing season for tomatoes in the UK, natural daylight has an intensity higher than 30 000 lux.
The farmer therefore decided to use the following conditions in his greenhouse during the day:
•        20°C
•        0.1% CO_2
•        no extra lighting.
Suggest why the farmer decided to use these conditions for growing the tomatoes.
You should use information from the scientists’ graph in your answer.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(4)
(Total 17 marks)
Q5.
This question is about photosynthesis.
(a)     Plants make glucose during photosynthesis. Some of the glucose is changed into insoluble starch.
What happens to this starch?
Tick () one box.
 
The starch is converted into oxygen. |
The starch is stored for use later. |
The starch is used to make the leaf green. |
(1)
(b)     A student investigated the effect of temperature on the rate of photosynthesis in pondweed.
The diagram shows the way the experiment was set up.
 
(i)      The student needed to control some variables to make the investigation fair.
State two variables the student needed to control in this investigation.
1. ____________________________________________________________
2. ____________________________________________________________
(2)
(ii)     The bubbles of gas are only produced while photosynthesis is taking place.
What two measurements would the student make to calculate the rate of photosynthesis?
1. ____________________________________________________________
2. ____________________________________________________________
(2)
(c)     The graph shows the effect of temperature on the rate of photosynthesis in the pondweed.
 
Temperature in °C
(i)      Name the factor that limits the rate of photosynthesis between the points labelled A and B on the graph.
______________________________________________________________
(1)
(ii)     Suggest which factor, carbon dioxide, oxygen or water, might limit the rate of photosynthesis between the points labelled C and D on the graph.
______________________________________________________________
(1)
(Total 7 marks)

Mark schemes
Q1.
(a)     (i)      LHS = water
accept H_2O
do not accept H^2O / H2O
1
RHS = oxygen
accept O_2
do not accept O / O^2 / O2
1
(ii)     light / sunlight
ignore solar / sun / sunshine
do not allow thermal / heat
1
(iii)    chloroplasts
allow chlorophyll
1
(b)     (i)      20
1
(ii)     any one from:
•        light (intensity)
•        temperature.
1
(c)     (i)      To increase the rate of growth of the tomato plants
1
(ii)     Because it would cost more money than using 0.08%
1
Because it would not increase the rate of photosynthesis of the tomato plants any further
1
[9]
Q2.
(a)     (i)      in the direction of the force of gravity
1
(ii)     against the force of gravity
1
(b)     (i)      diagram completed to show stem bending / leaning towards the window
the bend / lean can be at / from any point above pot level
ignore any leaves
1
(ii)     more light (for leaves)
ignore heat
1
more photosynthesis / biomass / glucose
ref to ‘more’ needed once only, eg ‘more light for photosynthesis’ = 2 marks
if no other marks given allow 1 mark for ‘to get light for photosynthesis’
1
[5]
Q3.
(a)     6H_2O
in the correct order
1
C_6H_12O_6
1
(b)     (i)      control
do not accept ‘control variable’
allow:
to show the effect of the organisms
or
to allow comparison
or
to show the indicator doesn’t change on its own
1
(ii)     snail respires
1
releases CO_2
1
(iii)    turns yellow
1
plant can't photosynthesise so CO_2 not used up
1
but the snail (and plant) still respires so CO_2 produced
1
[8]
Q4.
(a)     LHS = water
1
RHS = glucose
1
(b)     any three from:
•        (measure) temperature
ignore reference to fair test
•        to check that the temperature isn’t changing
•        rate of reaction changes with temperature
•        temperature is a variable that needs to be controlled
allow lamp gives out heat
3
(c)     (i)      10
correct answer = 2 marks
allow 1 mark for:  
 
allow 1 mark for correct calculation without removal of anomalous result ie 15
2
(ii)     graph:
allow ecf from (c)(i)
label on y-axis as ‘number of bubbles per minute’
1
three points correct = 1 mark
allow ± 1 mm
four points correct = 2 marks
2
line of best fit = smooth curve
1
(iii)    as distance increases, rate decreases – pro
allow yes between 20 – 40
1
but should be a straight line / but line curves – con / not quite pro
allow not between 10 – 20
if line of best fit is straight line, allow idea of poor fit
1
(d)     any four from:
•        make more profit / cost effective
•        raising temp. to 25 °C makes very little difference at 0.03% CO_2
•        (at 20 °C) with CO_2 at 0.1%, raises rate
•        (at 20 °C with CO_2 at 0.1%) → >3x rate / rises from 5 to 17
•        although 25 °C → higher rate, cost of heating not economical
•        extra light does not increase rate / already max. rate with daylight
accept ref to profits c.f. costs must be favourable
4
[17]
Q5.
(a)    The starch is stored for use later
no mark if more than one box is ticked
1
(b)     (i)      any two from:
do not accept temperature
apply list principle
ignore reference to time
•        carbon dioxide (concentration)
•        light intensity
•        light colour / wavelength
allow 1 mark for light if neither intensity or colour are awarded
•        pH
•        size / amount of pondweed / plant
•        same / species / type pondweed
•        amount of water in the tube
ignore amount of water alone
2
(ii)     number / amount of bubbles or amount of gas / oxygen
allow volume of bubbles (together)
ignore ‘the bubbles’ unqualified
1
(relevant reference to) time / named time interval
allow how long it bubbles for
do not accept time bubbles start / stop
ignore speed / rate of bubbling
ignore instruments
do not accept other factors eg temperature
accept how many bubbles per minute for 2 marks
1
(c)     (i)      temperature
allow heat / cold / °C
1
(ii)     carbon dioxide / CO_2
allow CO2
do not accept CO^2
1
[7]