Q1.          (a)      Complete the equation for photosynthesis.
  lightenergy
......................... + .........................   ......................... + oxygen
(2)
(b)     Scientists investigated how temperature affects the rate of photosynthesis.
The scientists grew some orange trees in a greenhouse.
They used discs cut from the leaves of the young orange trees.
The scientists used the rate of oxygen production by the leaf discs to show the rate of photosynthesis.
(i)      The leaf discs did not produce any oxygen in the dark.
Why?
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(1)
(ii)     The leaf discs took in oxygen in the dark.
Explain why.
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(2)
(c)     In their investigation, the scientists measured the rate of oxygen release by the leaf discs in the light. The scientists then measured the rate of oxygen uptake by the leaf discs in the dark.
The graph shows the effect of temperature on
•   oxygen production in the light
•   oxygen production in the light added to oxygen uptake in the dark.

Use the information from the graph to answer each of the following questions.
(i)      Describe the effect of temperature on oxygen production in the light.
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(2)
(ii)     Explain the effect of temperature on oxygen production in the light when the temperature is increased:
from 25 °C to 35 °C
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from 40 °C to 50 °C.
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(2)

(d)     A farmer in the UK wants to grow orange trees in a greenhouse. He wants to sell the oranges he produces at a local market.
He decides to heat the greenhouse to 35 °C.
Explain why he should not heat the greenhouse to a temperature higher than 35 °C.
Use information from the graph in your answer.
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(3)
(Total 12 marks)
 Q2.          Photosynthesis takes place the leaves of green plants.
(a)     Write a balanced chemical equation for the formation of glucose by photosynthesis.
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(3)
b)     Describe two ways that the rate of photosynthesis can be decreased without lowering the temperature.
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(2)

(c)     Some students decided to investigate the effect of temperature on the rate of photosynthesis in pond weed. They set up the apparatus and altered the temperature using ice and hot water. The counted the number of bubbles given off in a minute at different temperatures. They obtained the following results.

(i)      Plot the points on the graph.

(3)

(ii)     Use your graph to predict the number of bubbles per minute at 25 °C.
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(1)
(iii)     Suggest a reason why the rate of photosynthesis seems to decrease in this pondweed after 40 °C.
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(1)
(Total 10 marks)

Q3.          The graph shows how the rate of photosynthesis is affected by different conditions.

(a)     What patterns can you find from this graph?
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(5)

(b)     How useful could this information be to a grower using glasshouses? Give reasons for your answer.
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(2)
(Total 7 marks)

Q4.          Low light intensity is one factor that limits the yield of a crop.
          In Britain, many tomato growers use artificial lights to increase the yield of tomato crops.
          The table shows the amount of natural daylight and artificial lamplight received by a tomato crop grown in a greenhouse.
 	Natural daylight received
by tomato plant	Artificial lamplight given
to tomato plant	Total light energy received	Percentage increase in growth	
Month	Day length
in hours	Light
energy received
by plant
per day
in J/cm2	Hours of light given per day	Light energy received
by plant
per day
in J/cm2	by plant per day
in J/cm2	resulting from artificial light	
January	8.1	239	18	492	731	206	
February	9.9	492	18	492	984	100	
March	11.9	848	12	328	1176	39	
April	13.9	1401	2	55	1456	4	
May	15.5	1786	0	0	1786	0	
June	16.6	1960	0	0	1960	0	
July	16.2	1849	0	0	1849	0	
August	14.7	1561	0	0	1561	0	
September	12.8	1064	2	55	1119	5	
October	10.6	614	11	301	915	49	
November	8.8	288	18	492	780	171	
December	7.6	183	18	492	675	269	
 
(a)     Describe the pattern for the amount of light energy received from natural daylight by a tomato plant during the day.
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(b)     A tomato plant needs 600 J of light energy per cm2 each day to grow and produce tomatoes.
          Use this information and data from the table to suggest an explanation for the pattern of the artificial light given to the tomato plants.
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(2)
(Total 5 marks)
 Q5.          The graph shows the concentration of carbon dioxide in the air in a greenhouse full of tomato plants, measured over a period of 24 hours.

(a)     Explain why the concentration of carbon dioxide in the air in the greenhouse increased between X and Y.
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(2)

(b)     Explain why the concentration of carbon dioxide in the air in the greenhouse decreased between Y and Z.
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(2)
(Total 4 marks)
 Q6.          The graph shows the effect of temperature on photosynthesis.

(a)     Between which temperatures is the rate of photosynthesis fastest?
............................... and .......................... °C		(1)
(b)     Suggest why the rate of photosynthesis stays the same between these two temperatures.
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(2)
(c)     A greenhouse owner wants to grow lettuces as quickly and cheaply as possible in winter.
          At what temperature should he keep his greenhouse in order to grow the lettuces as quickly and cheaply as possible?
.......................... °C
          Explain your answer.
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(3)
(Total 6 marks)
 Q7.          The graph shows the uptake of carbon dioxide and the release of carbon dioxide by a bean plant on a hot summer’s day.

(a)     At which two times in the day did the rate of photosynthesis exactly match the rate of respiration in the bean plant?
1 ......................................................... 2 .........................................................
(1)
(b)     The bean plant respires at the same rate all through the 24 hour period.
(i)     How much carbon dioxide is released each hour during respiration?
                             ......................................................... arbitrary units
(1)

(ii)     How much carbon dioxide is used by photosynthesis in the hour beginning at 3 pm?
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               Answer = ......................................................... arbitrary units
(1)

(c)     Over the 24 hour period, the total amount of carbon dioxide taken in by the bean plant was greater than the total amount of carbon dioxide given out by the bean plant.
Explain, in detail, why this was important for the bean plant.
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(2)
(Total 5 marks)
 Q8.          The diagram shows some plants growing in a greenhouse on a hot summer’s day.

          Which one of the following factors is most likely to limit the rate of photosynthesis at this time?
•    carbon dioxide concentration 
•    light intensity
•    temperature
Factor ............................................................................................
          Explain the reason for your answer.
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(Total 4 marks)
Q9.          In this country most tomatoes are grown in greenhouses.

(a)     Suggest one way in which a grower could increase the yield of tomatoes from plants growing in his greenhouse.
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(1)
(b)     Large supermarkets often import tomatoes from overseas.
(i)      Suggest two reasons why a supermarket might decide to import tomatoes rather than buy them from British growers.
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(ii)     Importing tomatoes may be more damaging to the environment than selling tomatoes grown in this country.
         Explain why.
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(2)
(Total 5 marks)

Q10.          Changing the conditions in which plants grow affects how fast they grow.
The diagram shows a propagator in which scientists can control temperature, light intensity and carbon dioxide concentration.

The graph shows the effects of changing the temperature, light intensity and carbon dioxide concentration on the growth of lettuce plants.

(a)     Describe and explain the effect of increasing light intensity on the mean mass of lettuce plants at 4% carbon dioxide and 15 °C.
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(3)

(b)     Growers wish to make maximum profits from their lettuces.
          What do they need to consider before making decisions about the growing conditions for their lettuces?
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(2)
(c)     The nutrient solution contains nitrate ions and magnesium ions.
          Complete the table to show the functions of these ions in plants and their deficiency symptoms.
Ion	Function in plants	Deficiency symptoms	
Nitrate	.........................................................
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Magnesium	.........................................................
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(4)
(Total 9 marks)
 M1.          (a)     LHS: carbon dioxide AND water
in either order
accept CO2 and H2O
allow CO2 and H2O
if names given ignore symbols
do not accept CO2 / H2O / Co / CO
ignore balancing
1
RHS: sugar(s) / glucose / starch / carbohydrate(s)
accept C6H12O6
allow C6H12O6
do not accept C6H12O6
1
(b)     (i)      light is needed for photosynthesis
or
no photosynthesis occurred (so no oxygen produced)
1
(ii)     oxygen is needed / used for (aerobic) respiration
full statement
respiration occurs or oxygen is needed for anaerobic respiration gains 1 mark
2
(c)     (i)      (with increasing temperature) rise then fall in rate
1
use of figures, ie
max. production at 40 °C
or maximum rate of 37.5 to 38
1
(ii)     25 – 35 °C
either  faster movement of particles / molecules / more collisions or particles have more energy / enzymes have more energy
1
or temperature is a limiting factor over this range
40 – 50 °C
denaturation of proteins / enzymes
ignore denaturation of cells
ignore stomata
1
(d)     above 35 °C (to 40 °C) – little increase in rate
or > 40 °C – causes decrease in rate
1
so waste of money or less profit / expensive
1
because respiration rate is higher at > 35 °C
or
respiration reduces the effect of photosynthesis
1
[12]
 M2.          (a)     reactants: CO2 + H2O
1
products: C6H12O6 + O2
1
balance:
6CO2 + 6H2O  →  C6H12O6 + 6O2
1

(b)     1 mark each for any of the following
ideas:
lower CO2 concentration
lower light intensity
decrease water availability
alter light wavelength or colour
accept more green light
2
(c)     (i)      scales correctly constructed
i.e. equal intervals along each axis
1
points plotted correctly
1
appropriate line correctly drawn
accept dot to dot or line of best fit
cancel if line extends through zero or beyond 50°C
1
(ii)     18 – 19 (bubbles per minute)
1
(iii)     heat denatures enzymes or destroys
membranes or ruptures cells or
destroys cells
do not accept kills enzymes
1
[10]
          (a)     + light = + photosynthesis
+ light = + photosynthesis to a limit
limit depends on temp/CO2 levels
+ CO2 = + photosynthesis
+ temp = + photosynthesis
each for 1 mark
5
(b)     need to raise optimum levels
when one other raised
to get max/economic yield
each for 1 mark
2
[7]
 M4.          (a)     low in winter / named months /when the days are short
accept increases in spring / Dec – June
1
          high in summer / named month(s) / (when days are long
decreases in autumn / June – December
1

         reasonable quantitative statement
accept any reasonable calculated /
translated quantitative statement
higher in summer than in winter for 2 marks
comparative statements may be worth 2 marks
but
8/11 times higher in summer than in
winter for 3 marks
1
(b)     no artificial light given in summer / light only given in winter
          since natural light greatly exceeds minimum / 600 J (required to produce
tomatoes)
accept day length if linked to light energy
          OR
          light only given in winter
          as natural light less than the minimum
needed (to grow them) or 600 J
          OR
          for 2 marks:
percentage increase in growth from artificial] light only significant in winter
2
[5]
 M5.          (a)     respiration
reject start respiring / respire only at night
1
no photosynthesis because no light
1

(b)     photosynthesis rate greater than respiration rate
1
reject no respiration / photosynthesis only
photosynthesis since light
1
[4]
 M6.          (a)     21.5 – 22 and 27 – 27.5
for 1 mark
1
(b)     ideas of
limiting factor / shortage of
e.g. light / carbon dioxide / water / chlorophyll
each for 1 mark
(allow 1 for ‘maximum / optimum rate of enzyme activity if no reference to limiting factors) (ignore denaturation)
2

(c)     21.5 – 22° C
(allow first figure from answer to (i) so that no ‘double-penalty but only if this first answer is 20 or greater)
          maximum rate of photosynthesis / highest / fastest
but related to flat part of curve
          most economical heating / cheapest related to heating
must relate to the temperature the candidate has given
each for 1 mark
3
[6]
 M7.          (a)     7.15 to 7.45 am and 7.15 to 7.45 pm
both required, either order
accept in 24 hr clock mode
1

(b)     (i)      11
1

(ii)     32.5 to 33
allow answer to (b)(i) + 21.5 to 22
1

(c)     any two from:
•        more photosynthesis than respiration
•        more biomass / carbohydrate made than used
allow more food made than used
•        so plant able to grow / flower
accept plant able to store food
2
[5]
 M8.          carbon dioxide concentration
1
          since atmospheric concentration very low / value give e.g. 0.03%
allow carbon dioxide used up
1
          temperature high
allow if light chosen as a factor
1
          light intensity high
allow If temperature chosen as a factor
1
[4]
 M9.          (a)     any one from:
•        increase / give light
•        increase temperature / make warmer
          award marks if the method by which these could be done is given
eg leave lights on all night or use a heater
•        increase / give CO2
•        add fertiliser / nutrients / minerals / named
allow nitrogen
ignore ‘food’
1

(b)     (i)      any two from:
•        cheaper
allow grow faster / more grown
•        better quality / flavour
ignore size
•        available all year
accept converse if clear that answer refers to use of British tomatoes
allow ‘Fair Trade’
2

(ii)     any two from:
•        greater distance or more food
miles or more transport
         idea of more needed only once
•        transport needs (more) energy / fuel
•        reference to eg greenhouse effect / global
warming / pollution / CO2  release / carbon footprint
ignore ozone
2
[5]

 M10.          (a)     any three from:
•        ((mean) mass) increases up to 7 / 8 units (of light) then levels off
•        light limiting factor up to 7 / 8 units
•        for photosynthesis
must be in correct context
•        other factor / temperature limiting above 7 / 8 units
3

(b)     any two from:
•        cost of providing conditions / heat / light / CO2
•        effect of treatment on profit
allow too much of factor is wasteful
•        relevant use of data from graph eg limiting factors
•        named other factors eg fertiliser / pest control / weeds /
density of planting
allow taste / appearance
2

(c)     nitrate function
          produce amino acids / proteins / enzymes
ignore DNA
do not allow chlorophyll
1
          nitrate deficiency
          stunted growth
allow description
ignore plant dies
1
          magnesium function
          produce chlorophyll
ignore chloroplasts
1
          magnesium deficiency
          yellow leaves / plant
ignore plant dies
1
[9]