Photosynthesis & Leaf Structure (Cambridge (CIE) IGCSE Biology)

Exam Questions

4 hours32 questions
1a
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6 marks

Water is required for the process of photosynthesis.

(i)

Describe where and how water enters a plant.

[3]

(ii)

Describe one function of water in a plant other than for photosynthesis.

[1]

(iii)

State the name of the tissue in a plant that transports water.

[1]

(iv)

State the name of the part of a leaf through which most water vapour is lost from the plant

[1]

1b
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3 marks

Chlorophyll is another requirement for photosynthesis to occur.

Complete the following sentences on chlorophyll.

Chlorophyll is a pigment found in ___________________ within plant cells. It is responsible for transferring energy from ___________________ into __________________ energy.

1c
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2 marks

State one other raw material besides water that is required for photosynthesis and describe how the plant obtains this substance.

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2a
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3 marks

(i)

State the word equation for photosynthesis.

[2]

(ii)

State the name of the green substance plants need for photosynthesis.

[1]

2b
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3 marks

A student wanted to test the effect of temperature on the rate of photosynthesis.

Fig. 1 shows how the student set up his investigation.

aquatic-plant

Fig. 1

(i)

Identify the gas that is being collected in Fig. 1.

[1]

(ii)

Explain the purpose of using an aquatic plant in this investigation.

[2]

2c
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2 marks

The temperature is increased from 10°C to 25°C.

State and explain the observation that the student would make.

2d
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1 mark

State one factor, other than temperature, that affects the rate of photosynthesis.

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3a
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4 marks

Carbohydrates are produced during photosynthesis.

Describe four ways in which a plant may use the carbohydrates produced during photosynthesis.

3b
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2 marks

The carbohydrates produced during photosynthesis may also be converted to lipids and amino acids.

State the function of lipids and amino acids in a plant.

3c
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2 marks

Nitrate is an important source of nitrogen which is needed to make amino acids.

Other than nitrogen, identify two other chemical elements that could be found in amino acids.

3d
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2 marks

Some plants may grow in nutrient poor soils where they are not able to absorb enough nitrate through their roots.

Describe the appearance of a plant that is deficient in nitrate.

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4a
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2 marks

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A gardener is setting up his greenhouse.

He is given advice from two friends on the correct conditions for his greenhouse to grow the most vegetables.

Friend X suggested that he provide plenty of water to his vegetables but should cover all the windows in black card to stop the plants getting too hot.

Friend Y suggested that he provide plenty of water and open the windows of the greenhouse but did not suggest covering them.

Should the farmer follow the advice of friend X or friend Y?

Explain your choice.

4b
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3 marks

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The graph in Fig. 1 shows how the rate of photosynthesis of strawberry plants is affected by changes in three limiting factors.

light-intensity-and-strawberry-plants-1

Fig. 1

Identify which three limiting factors were investigated to produce this graph.

4c
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3 marks

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Finding the optimum conditions for photosynthesis will ensure that growth is maximised.

Using Fig. 1 , complete the following sentences to identify which conditions gave the fastest rate of photosynthesis and therefore, the maximum growth.

Optimum temperature would be __________

Optimum carbon dioxide % would be __________

Optimum light intensity would be __________

4d
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2 marks

Extended only

A gardener used the results in Fig. 1 to decide how much carbon dioxide to pump into the greenhouse.

He decided to increase the atmospheric levels to 600 ppm rather than 700 ppm.

Suggest why he made this decision.

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5a
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4 marks

A plant leaf contains various structures that makes it adapted for the process of photosynthesis.

Complete the following by drawing lines to connect each listed structure with the correct adaptation.

Structure

 

Adaptation

 

 

 

Waxy cuticle

 

Allows gas exchange to occur

 

 

 

Stomata

 

Tightly packed with chloroplasts for maximum absorption of light

 

 

 

Palisade mesophyll

 

Protect the leaf from water loss

 

 

 

Spongy mesophyll

 

Increases the surface area to volume ratio for the diffusion of gases

5b
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4 marks

Fig. 1 shows the cross section of a leaf.

fig

Fig. 1

Structure Y represents a vascular bundle.

(i)

Identify two types of tissue found in structure Y.

[2]

(ii)

Describe the function of each type of tissue identified at part (i).

[2]

5c
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3 marks

Layer X and Z in Fig. 1 form the outer boundaries of the leaf.

(i)

State one visible difference between layer X and Z.

[1]

(ii)

The cells in layer X are transparent.

Explain the importance of this to the plant.

[2]

5d
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3 marks

Carbon dioxide must enter the chloroplasts within plant cells for photosynthesis to occur.

Describe the movement of carbon dioxide from the atmosphere into the chloroplasts.

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1a
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4 marks

Fig. 1 is a diagram of a variegated leaf from a plant. The plant was exposed to sunlight so that it could photosynthesise.

cie-igcse-2023-specimen-q4a

Fig. 1

A student tested the leaf for starch and found that:

  • Starch was present in the green part of the leaf

  • There was no starch in the white part of the leaf.

Explain the results of this test.

1b
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2 marks

Testing a leaf for the presence of starch involves several steps. Explain the following:

(i)

 Boiling the leaf at the start of the procedure.

[1]

(ii)

Heating ethanol in a water bath.

[1]

1c
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3 marks

Extended only

Photosynthesis occurred in certain parts of the leaf in Fig. 1.

Give the balanced chemical equation for photosynthesis.

1d
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1 mark

Extended only

Energy is converted from one form to another during the process of photosynthesis.

Describe this energy conversion.

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2a
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5 marks

In an investigation, the carbon dioxide concentration in the air above a crop of maize plants was measured for 24 hours.

There was no wind blowing during the 24 hours of the investigation.

The results of this investigation are shown in Fig. 1.

0610p31q9a

Fig. 1

(i)

State the two times, on Fig. 1, at which the carbon dioxide concentration in the air was 37 arbitrary units.

[1]

(ii)

Calculate the difference in the carbon dioxide concentration in the air between 04:00 (sunrise) and 12:00 (midday) on Fig. 1. Give your answer in arbitrary units.

[1]

(iii)

Explain why the concentration of carbon dioxide decreases between 04:00 and 09:00.

[3]

2b
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2 marks

State two environmental factors that would affect the results of this investigation.

2c
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3 marks

Describe and explain the concentration of carbon dioxide between 16:00 and sunset in Fig. 1.

2d
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2 marks

The concentration of carbon dioxide was highest at sunrise.

Suggest a reason for this.

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3a
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3 marks

Fig. 1 shows a diagram of a leaf.

cie-igcse-2018-s2-may-p3-q2a-leaf

Fig. 1

  • The part of the leaf labelled G contains no chlorophyll and is a white colour.

  • The part of the leaf labelled H contains chlorophyll and is a green colour.

Glucose produced during photosynthesis is stored in the leaf as starch.

The leaf was boiled in ethanol to remove the chlorophyll. The leaf was then tested for the presence of starch with iodine solution. 

(i)

Predict the colour of the part of the leaf labelled G after iodine solution has been added.

[1]

(ii)

Predict the colour of the part of the leaf labelled H after iodine solution has been added. 

[1]

(iii)

State a conclusion about chlorophyll from this investigation.

[1]

3b
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1 mark

A similar leaf was kept in the dark for 24 hours and then tested for the presence of starch.

The leaf contained no starch.

Explain why the leaf contained no starch.

3c
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2 marks

Extended only

Glucose is converted into insoluble starch for storage.

Use your knowledge about osmosis to explain why plant cells do not use glucose as a storage molecule.

3d
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3 marks

A student modified the experiment from part (a) in order to investigate if light is needed for photosynthesis. Before carrying out the experiment, the student had to include an important step to ensure they obtain accurate results.

(i)

Describe this step.

[1]

(ii)

Explain the importance of the step described at part (i).

[2]

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4a
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4 marks

A group of students used an aquatic plant to investigate the effect of temperature on the rate of photosynthesis.

Fig. 1 shows the apparatus the students used.

cie-igcse-2018-s3-may-p3-q2b-photosynthesis-equipment

Fig. 1

The students counted the number of bubbles of gas the aquatic plant produced, in two minutes, at different temperatures.

Fig. 2 shows a graph of their results.

cie-igcse-2018-s3-may-p3-q2b-graph-of-results

Fig. 2

(i)

State the temperature at which the aquatic plant produced the most bubbles of gas in two minutes.

Give your answer in °C.

[1]

(ii)

Use Fig. 2 to find the number of bubbles of gas produced by the aquatic plant, in two minutes, at 15 °C and at 25 °C. 

[1]

(iii)

Use your answer to (a)(ii) to calculate the percentage increase in the number of bubbles of gas produced by the aquatic plant at 15 °C and at 25 °C.

Show your working. 

[2]

4b
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3 marks

Describe the results shown in Fig. 2. 

4c
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2 marks

Extended only

Use your knowledge on enzymes to suggest an explanation for the results obtained between 30°C and 40°C in Fig. 2.

4d
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1 mark

The students added sodium hydrogen carbonate (NaHCO3) to the water in the beaker in Fig.1.

State the purpose of this.

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5a
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7 marks

Fig. 1 is a scanning electron micrograph of a vertical section through part of the leaf of a broad bean plant, Vicia faba.

cie-igcse-2018-s3-p4-q3

Fig. 1

(i)

State the names of the tissues labelled A and B.

[2]

(ii)

The cells in regions B and C in Fig. 1 have a large surface area.

Explain why this is necessary for the functioning of the leaf cells.

[3]

(iii)

Explain why there are many interconnecting air spaces within the leaf.

[2]

5b
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3 marks

Stomata are found on the lower surface of broad bean leaves.

Describe the function of stomata.

5c
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4 marks

Plants growing in soils lacking magnesium ions struggle to photosynthesise and therefore do not grow to their full potential.

Suggest an explanation why.

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1a
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2 marks

The rate of photosynthesis of terrestrial plants can be determined by measuring the uptake of carbon dioxide.

Explain why plants take up carbon dioxide during photosynthesis.

1b
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2 marks

The rate of photosynthesis of parts of individual leaves can be measured using a hand-held device as shown in Fig. 1.

cie-igcse-2019-paper4-2b

Fig. 1

This apparatus allows air to flow through the transparent chamber that encloses part of the leaf. The apparatus measures the carbon dioxide concentration of the air entering and leaving the chamber.

Explain how the results from the apparatus can be used to calculate the rate of photosynthesis.

1c
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10 marks

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A student used the apparatus shown in Fig. 1 to investigate the effect of temperature on the rate of photosynthesis of the leaves of Chinese plantain, Plantago asiatica, at two different concentrations of carbon dioxide, A and B.

Fig. 2 shows the results of the investigation.

cie-igcse-2019-paper4-2c

Fig. 2

(i)

State one environmental factor that should have been kept constant in this investigation.

[1]

(ii)

Describe the effect of temperature on the rate of photosynthesis when carbon dioxide concentration A was supplied.

Use the data from Fig. 2 in your answer.

[3]

(iii)

Calculate the percentage increase in the rate of photosynthesis at 30 °C when the carbon dioxide concentration was increased from A to B as shown in Fig. 2.

Show your working and give your answer to the nearest whole number.

[2]

(iv)

Explain the effect of increasing temperature on the rate of photosynthesis for carbon dioxide concentration B.

Use the term limiting factor in your answer.

[3]

(v)

The student concluded that carbon dioxide concentration is the factor limiting the rate of photosynthesis between 30 °C and 35 °C for the results shown for A in Fig. 2.

State the evidence for this conclusion.

[1]

1d
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2 marks

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A similar investigation was carried out on Arizona honeysweet, Tidestromia oblongifolia, that grows in Death Valley in California where the highest temperatures may be greater than 45 °C.

The results are shown in Fig. 3.

cie-igcse-2019-paper4-2d

Fig. 3

Predict and explain what would happen to the rate of photosynthesis if the investigation is continued at temperatures higher than 45 °C.

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2a
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2 marks

The apparatus shown in Fig. 1 was used to investigate the effects of different conditions on the rate of photosynthesis in an aquatic plant.

Mwh8Idbd_picture10

Fig. 1

A student investigated the effects of light and carbon dioxide on the rate of photosynthesis.

The number of bubbles of oxygen produced in one minute was counted in four different conditions.

Table 1 shows the results.

Table 1

test

conditions

number of bubbles of oxygen per minute

light

carbon dioxide source added to the water

1

present

no

2

2

absent

no

0

3

present

yes

20

4

absent

yes

0

State two conclusions about the conditions needed for photosynthesis using the information in Table 1.

2b
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4 marks

The investigation was carried out at 15 °C. It was repeated at 25 °C.

Suggest and explain the effect this had on the results of test 2 and test 3.

2c
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2 marks

Carbon dioxide enters plant cells by diffusion.

The word diffusion on the left can be joined to two boxes on the right to make two correct statements about diffusion. 

Draw two straight lines from diffusion to the boxes to complete the two statements.  

2018-nov-s1-061031-q2c
2d
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3 marks

Table 2 shows the volume of water absorbed, as well as the water usage by a plant over a period of 24 hours.

Table 2

total volume of water absorbed by the roots / cm3

volume of water lost by transpiration / cm3

volume of water used during photosynthesis / cm3

265

262.4

2.6

(i)

Calculate the percentage of water used during photosynthesis. 

Show your working and give your answer to two decimal places.

[2]

(ii)

Use the information in Table 2 and your answer at part (i) to explain why water is usually not a limiting factor of photosynthesis.

[1]

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3a
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2 marks

An investigation was carried out to test the effect of temperature on the rate of photosynthesis of pondweed.

The volume of oxygen produced per hour was measured. The results can be seen in Table 1.

Table 1

temperature / °C

rate of photosynthesis / cm3 hour-1

test 1

test 2

test 3

mean

20

18.4

19.3

19.6

19.1

25

31.6

35.1

31.9

32.8

30

42.9

44.2

44.9

44.0

35

40.6

39.8

42.0

40.8

40

23.1

20.5

22.4

22.0

45

1.9

14.2

2.2

X

Calculate the mean rate of photosynthesis per hour when the temperature was 45 °C.

3b
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5 marks

Plot the results from Table 1 onto an appropriate graph using the graph paper in Fig. 1.

graph-paper-1

Fig. 1

3c
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4 marks

Describe and explain the results shown in the graph.

3d
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4 marks

A farmer growing strawberries in his greenhouse used the results in Table 1 to decide on the best temperature for his greenhouse. He decided to heat the greenhouse to 30 °C.

When the farmer measured the rate of photosynthesis of his plants, he found the rate to be 11.5% slower than the data suggested.

Calculate the rate of photosynthesis that the farmer actually achieved at 30 °C.

3e
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2 marks

Extended only

Suggest why the farmer may not have achieved a rate of photosynthesis as high as the data in Fig. 1 predicted.

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4a
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4 marks

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Fig. 1 shows the effect of several different factors on the growth of strawberry plants in a greenhouse.

limiting-factors-and-photosynthesis-2

Fig. 1

Describe and explain how temperature and light intensity affected the rate of photosynthesis up until 20°C.

4b
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2 marks

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Identify the limiting factor(s) between point X and Y in Fig. 1.

4c
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2 marks

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Calculate the percentage difference in the rate of photosynthesis at 25°C in the plants grown at low and high light intensity. Show your working and give your answer to one decimal place.

4d
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2 marks

Extended only

Explain why light intensity is no longer limiting the rate of photosynthesis at temperatures higher than 30°C.

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5a
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2 marks

A student carried out an investigation into the effect of soil magnesium on plant growth.

In this investigation, the student set up two different environments as follows:

  1. One plant was grown in sterile soil, provided with distilled water and placed in bright light.

  2. One plant was grown in sterile soil, provided with magnesium dissolved in distilled water and placed in bright light.

Predict what the student will have observed after two weeks of growing in these conditions.

5b
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4 marks

Explain your prediction from part (a).

5c
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3 marks

When selecting the plants for the investigation in part (a), the student made sure that they picked plants with the same number of leaves.

Explain why this was necessary.

5d
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2 marks

One method that can be used to show that photosynthesis has occurred is to test the leaves with iodine.

Explain how this shows that photosynthesis has occurred.

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