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Question 1
Photosynthesis takes place within chloroplasts inside plant cells. |
a) | Name the two parts of a chloroplast in which the light-dependent and light-independent reactions of photosynthesis take place.
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b) | During photosynthesis, water undergoes the process of photolysis. Describe what happens in the photolysis of water.
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c) | The light-dependent reactions of photosynthesis synthesise ATP and reduced NADP. These products are then used in the light-independent reaction of photosynthesis. Describe one function of ATP in the light-independent reaction.
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d) | Describe one function of reduced NADP in the light-independent reaction.
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Question 2
The diagram below shows the reactions in the light-dependent stage of photosynthesis. |
a) | Name substances represented by letters A, B, and C in the diagram above.
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b) | In which part of a chloroplast do these reactions take place?
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c) | Use the diagram above to explain how NADP is reduced in the light-dependent reaction of photosynthesis.
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d) | Products from the light-dependent reactions of photosynthesis are used to make organic substances in the light-independent reactions. Describe how carbon dioxide is converted into organic substances during the light-independent stage of photosynthesis.
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Question 3
The diagram below shows the Calvin cycle. |
a) | Name enzyme A in the diagram above.
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b) | State the number of carbon atoms in each of the following molecules: i) GP ii) TP iii) RuBP
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c) | A decrease in temperature decreases the rate of the light-independent reaction. Use the diagram above to explain why.
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d) | The light-independent reaction relies on products from the light-dependent reaction. Describe how plants use light energy during the light-dependent reaction.
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Question 4
The diagram below shows the structure of a chloroplast. |
a) | Label the parts in which the following events take place: i) Storage of food ii) Light-dependent reactions iii) Light-independent reactions
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b) | In the light-dependent reaction of photosynthesis, light energy is used to generate ATP. Explain how.
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c) | Plants produce ATP in respiration as well as in photosynthesis. Explain why it is important for plants to produce ATP in respiration.
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d) | Explain why the increase in plant biomass is less than the mass of hexose sugars produced by the same plant.
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Question 5
The diagram below shows the effect of increasing carbon dioxide concentration on the rate of photosynthesis. |
a) | What is limiting the rate of photosynthesis between points 1 and 2? Explain your answer.
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b) | What is limiting the rate of photosynthesis between points 2 and 3? Explain your answer.
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c) | When investigating the effect of carbon dioxide on the rate of photosynthesis, the temperature should be kept constant. Explain why.
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d) | A scientist determined the amount of glycerate-3-phosphate (GP) and ribulose bisphosphate (RuBP) at increased carbon dioxide concentrations. He found that there was double the amount of GP compared to the amount of RuBP in high carbon dioxide concentrations. Explain why.
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Question 6
The diagram below shows three different photosynthetic pigments found in a type of red seaweed. Each curve represents the different wavelengths absorbed by each pigment.
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a) | Describe the role of chlorophyll in photosynthesis.
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b) | Describe what the graph above shows about chlorophyll a and phycocyanin.
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c) | Use the graph to identify the range of wavelengths of light that would be green in colour. Explain your answer.
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d) | Red seaweed can live in much deeper water than green seaweed. Use the diagram above to suggest why.
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Question 7
A group of scientists investigated the effect of manganese deficiency on the production of triose phosphate in some plants. They grew the plants in the same conditions with their roots suspended in a growth medium containing all the nutrients they needed to grow. 12 days before the experiment they transferred half of the plants to a growth medium without manganese. They placed both groups of plants in the dark for 8 hours before transferring them to the light where they measured the concentration of triose phosphate every 4 hours. Their results are shown in the table below.
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a) | Explain why the plants were left in the dark for 8 hours before the experiment started.
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b) | Explain why the scientists grew all plants in the same conditions for up to 12 days before the experiment.
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c) | Some scientists believe that manganese deficiency leads to reduced electron transfer. Explain how this reduction would lead to a decrease in triose phosphate production in the manganese-deficient plants.
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d) | Explain why manganese deficiency leads to a decrease in carbon dioxide uptake.
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Question 8
A student investigated the uptake of carbon dioxide by chloroplasts. She used two different test tubes, one containing stroma and grana, the other containing just stroma. She measured carbon dioxide uptake in each test tube. Her results are shown below.
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a) | Predict carbon dioxide uptake if the test tube containing stroma and grana was placed in the dark. Give a reason for your answer.
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b) | Explain why the carbon dioxide uptake is less in the test tube containing only the stroma.
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c) | Another student used a test tube containing stroma and added ATP and reduced NADP. She found that the carbon dioxide uptake was very similar to the test tube containing the stroma and grana. Explain why.
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d) | Some weed killers work by inhibiting the transfer of electrons in photosynthesis. Another student added some weed killer to a test tube containing the stroma and grana. Explain how this would affect the uptake of carbon dioxide.
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Question 9
A scientist investigated how the concentrations of carbon dioxide, glycerate-3-phosphate (GP), and ribulose bisphosphate (RuBP) changed over time. After 800 seconds, the scientist turned off the carbon dioxide supply. The diagram below shows their results.
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a) | Explain why the concentration of GP remained constant between 0 and 800 seconds.
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b) | Explain why the concentration of GP decreased when the carbon dioxide supply was turned off.
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c) | Explain why the concentration of RuBP increased when the carbon dioxide supply was turned off.
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d) | Another scientist carried out a very similar experiment but used a higher concentration of carbon dioxide. The relative concentrations of GP and RuBP remained the same. Suggest two reasons for this.
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Question 10
A scientist investigated the rate of photosynthesis and respiration by a plant throughout the day. His results are shown below.
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a) | Explain the shape of the curve for the rate of photosynthesis.
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b) | Explain the shape of the curve for the rate of respiration.
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c) | Describe what is happening at the points labelled as Z in the diagram above.
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d) | Some scientists suggest that the increase in the rate of photosynthesis causes the increase in the rate of respiration. Suggest how this could happen.
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Question 11
Photosynthetic pigments are arranged into groups known as photosystems I and photosystems II. |
a) | Name the primary photosynthetic pigment in both photosystems.
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b) | Name an example of an accessory pigment.
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c) | Describe the importance of photosynthetic pigments in photosynthesis.
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d) | A student investigated the rate of photosynthesis in two plant species at different light intensities. Their results are shown in the diagram below.
Use the diagram to explain which species is adapted for living in shaded conditions.
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Question 12
A student carried out an experiment to investigate the effect of temperature on the rate of photosynthesis. Their results are shown in the diagram below.
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a) | Calculate the percentage increase in the rate of photosynthesis as temperature is increased from 20°C to 30°C. Give your answer to 2 decimal places.
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b) | Describe the effect of increasing leaf temperature on the rate of photosynthesis.
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c) | Another student repeated this experiment but at a lower carbon dioxide concentration. They did not get any results for temperatures 40°C and 50°C. Suggest why.
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d) | The light-independent reaction of photosynthesis involves the synthesis of triose phosphate. Describe the uses of triose phosphate in the cells of a leaf.
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