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Question 1
Plants are called producers because they make their own food from a process called photosynthesis. |
a) | Write the balanced symbol equation for photosynthesis.
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b) | Plants need energy to produce glucose. Where do plants get this energy from?
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c) | Which part of a plant cell absorbs the energy needed for photosynthesis?
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d) | Explain why photosynthesis is considered an endothermic reaction.
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e) | Give two uses of the glucose produced in photosynthesis.
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Question 2
In an experiment, a student measures the rate of photosynthesis of a pondweed at different light intensities. The results are shown in the following table. |
a) | Using the data in the table, plot a graph of light intensity against rate of photosynthesis.
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b) | Describe the relationship between light intensity and the rate of photosynthesis.
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c) | At light intensities between 0 and 700 lux, light was a limiting factor for photosynthesis. What evidence is there for this in the table?
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d) | Give one factor that could have limited the rate of photosynthesis when the light intensity was between 800 and 1000 lux.
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e) | The lamp gives out heat as well as light. What could the students do to make sure that heat from the lamp did not affect the rate of photosynthesis?
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Question 3
The diagram below represents a section of a leaf under the microscope, where photosynthesis takes place. |
a) | Identify and describe the role of two structures in the leaf that are involved in photosynthesis.
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b) | In a certain plant species, it is observed that the leaves have fewer stomata than a typical plant. Suggest how this could impact the rate of photosynthesis.
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c) | The plant also has a very thick waxy cuticle. Suggest the environment in which the plant lives and why having fewer stomata and a thick waxy cuticle is a useful adaptation.
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Question 4
A commercial greenhouse grower wants to maximise the rate of photosynthesis to increase the yield of a particular crop. The grower is considering changes in temperature, light intensity, and carbon dioxide concentration within the greenhouse. |
a) | Explain the role of carbon dioxide in photosynthesis and how increasing its concentration might affect the rate of photosynthesis.
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b) | Light intensity is a crucial factor in photosynthesis. Using the inverse square law, explain how the distance from the light source can influence the rate of photosynthesis in plants.
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c) | The grower also considers increasing the temperature inside the greenhouse. Explain how temperature can affect the rate of photosynthesis.
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d) | The grower measures the rate of photosynthesis at different temperatures. The results are shown in the table below: Using the data in the table, identify the optimal temperature for photosynthesis in this crop.
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e) | Scientists can collect the volume of oxygen produced by a plant in order to measure the rate of photosynthesis. Why is measuring the amount of oxygen a reliable way to determine the rate of photosynthesis?
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Question 5
A farmer plans to grow strawberries in a large greenhouse. The concentration of carbon dioxide in the atmosphere is approximately 0.04%. The farmer wants to add carbon dioxide to the greenhouse so that its concentration doubles to 0.08%. |
a) | Why does the farmer want to increase the carbon dioxide concentration in the greenhouse? A to increase the rate of growth of the strawberry plants B to increase the rate of respiration of the strawberry plants C to increase water uptake by the strawberry plants D to increase the sunlight energy used by the strawberry plants
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b) | Why does the farmer not use a concentration of carbon dioxide higher than 0.08%? Tick two boxes. A because it would cost more money than using 0.08% B because it would increase water loss from the strawberry plants C because it would not increase the rate of photosynthesis any further D because it would decrease the temperature of the greenhouse
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Scientists investigated the effects of these three factors on the rate of photosynthesis in strawberry plants growing in a greenhouse. The graph below shows the scientists’ results. |
c) | During the growing season for strawberries in the UK, natural daylight has an intensity higher than 30,000 lux. The farmer read about the scientists’ work and analysed their graph. The farmer decided to use the following conditions in his greenhouse during the day: • 20°C • 0.08% CO2 • no extra lighting Suggest why the farmer may have decided to use these conditions for growing the tomatoes. Give reasons for your suggestions.
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Question 6
Photosynthesis takes place in the leaves of plants. The micrograph below shows the underside of a leaf. |
a) | Label the stoma, guard cells, epidermal cells and chloroplasts.
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b) | Name the gases that:
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c) | Are the stomata larger during the day or at night? Explain your answer.
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d) | Suggest what would happen to the rate of photosynthesis if a plant's stomata get covered in dust.
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Question 7
The rate of photosynthesis in a plant depends on several external factors. These factors include light intensity and the availability of water. |
a) | Describe and explain the effects of two other factors that affect the rate of photosynthesis. You should include one or more sketches of graphs in your answer. Model answer
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