6.1. Photosynthesis
A subsection of Biology, 0610, through 6. Plant nutrition
Listing 10 of 307 questions
A student investigated the effect of the concentration of carbon dioxide on the rate of photosynthesis in an aquatic plant. Table 5.1 shows the results of the investigation. Table 5.1 concentration of carbon dioxide / ppm rate of release of oxygen / cm3 per hour 0.0 11.2 26.1 Describe and explain the results shown in Table 5.1. State why the temperature should have been kept constant during this investigation. Carbon dioxide is an example of a greenhouse gas. State the name of one other greenhouse gas. State the name of the chemical used to test for the presence of carbon dioxide and state the result of a positive test. chemical positive result Farmers use fertilisers on crops to improve crop growth. These fertilisers can cause pollution when washed into rivers. State the names of two other substances used to improve crop yield that can cause pollution.
0610_m21_qp_32
THEORY
2021
Paper 3, Variant 2
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For Examiner's Use shows four test-tubes that were set up and left for six hours at a constant warm temperature. water shrimp pond water with indicator D C A B sunlight sunlight lightproof box pond weed Hydrogencarbonate indicator (bicarbonate indicator) changes colour depending on the pH of gases dissolved in it, as shown in . indicator yellow indicator pinky red pH pH indicator purple concentration of carbon dioxide dissolved low high After six hours the colour of the indicator in all four tubes had changed. Complete Table 6.1 to predict the colour of the indicator after six hours. Table 6.1 tube colour of indicator at start colour of indicator after six hours A pinky red B pinky red C pinky red D pinky red For Examiner's Use Suggest the reason for the change in colour of the indicator in each of tubes A and D. tube A tube D shows a fifth tube, E, set up at the same time and in the same conditions as tubes C and D. E sunlight Suggest and explain the possible colour of the indicator in tube E after six hours. colour of indicator explanation
0610_s09_qp_2
THEORY
2009
Paper 2, Variant 0
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For Examiner's Use A student measured the uptake and release of carbon dioxide from a plant during 24 hours. It was a very bright, sunny day between sunrise and sunset. shows the student’s results. time / h uptake of carbon dioxide release of carbon dioxide no net uptake or release Use the information in to state the time that sunrise occurred. Using , state the times when there is no uptake or release of carbon dioxide. 1. 2. State why plants release carbon dioxide at night. Explain why it is important for plants that carbon dioxide uptake during the day is greater than carbon dioxide released at night. For Examiner's Use The yields of tomatoes grown in open fields in India are very low compared with yields of tomatoes grown in glasshouses in Europe. In a study, scientists in India grew tomato plants in glasshouses and in open fields nearby. The growth of the plants and the yields of tomatoes were recorded. The results are shown in Table 2.1. Table 2.1 tomato plants grown in glasshouses open fields mean final height of tomato plants / cm 84.1 69.0 mean number of leaves per tomato plant 123.0 82.0 mean fresh mass of tomato plants / g 988.3 491.7 mass of tomatoes per plant / g 2986.0 818.9 mean fresh mass of tomatoes / g 95.0 84.4 The mean fresh mass of tomatoes grown in glasshouses was greater than the mean fresh mass of tomatoes grown in open fields. Calculate the difference in mean fresh mass as a percentage of the mean fresh mass of tomatoes grown in open fields. Show your working. Answer = % For Examiner's Use Suggest how an increase in the height of the plants and the number of leaves on each plant affects the yield of tomatoes. The scientists made sure that the only differences between the two groups of plants were the result of the protection provided by the glasshouses. Suggest the factors that the scientists should have kept the same for the two groups of plants in this investigation. The growth and final yields of crops grown in open fields are often limited by environmental factors. Describe how these factors are controlled in commercial glasshouses to give high yields of crops such as tomatoes.
0610_s10_qp_31
THEORY
2010
Paper 3, Variant 1
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For Examiner's Use Write a balanced equation for photosynthesis using symbols. Plants that live in water are called hydrophytes. shows a cross-section of a leaf of the hydrophyte, Nuphar lutea. The leaves of N. lutea float on the surface of water. A B D C For Examiner's Use Complete Table 5.1 by describing the function of each feature. The function for feature A has already been completed. Table 5.1 feature function A transparent to allow light to penetrate into the leaf B …………………………………………………………………………… C …………………………………………………………………………… D …………………………………………………………………………… State and explain one way in which the leaves of N. lutea are adapted to their environment. For Examiner's Use A student investigated how magnesium affects the growth of duckweed, Spirodela polyrhiza. He prepared dishes each containing 30 plants of S. polyrhiza. Each dish contained a growth medium with different concentrations of a magnesium salt. shows one of the dishes. single plant of Spirodela polyrhiza After 33 days, the student counted the number of plants in each dish and recorded their appearance. The results are shown in Table 5.2. Table 5.2 concentration of magnesium salt / mg per dm3 number of plants after 33 days appearance of leaves after 33 days 0.05 yellow with some green patches 0.10 green with yellow spots 0.15 green with yellow spots 0.20 green 0.25 green For Examiner's Use Describe the effects of decreasing the concentration of magnesium salt on the growth of S. polyrhiza. Explain how magnesium deficiency affects the growth and appearance of this plant.
0610_s11_qp_31
THEORY
2011
Paper 3, Variant 1
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For Examiner's Use Define the term growth. Some students investigated the responses of tomato seedlings to receiving light from one side (unidirectional light). The students germinated tomato seeds in the dark and then placed the seedlings in test-tubes with water. The seedlings were treated in four different ways, E to H, as shown in . The responses of the seedlings are shown in . E F G H light cover that light cannot get through E F G H light For Examiner's Use Name the response shown by the tomato seedling, F, which has bent 90º towards the light. Using the results shown in , suggest what conclusions may be made about how the tomato seedlings detected the stimulus of unidirectional light. You may refer to the seedlings by the letters E to H. Explain the advantage of the response shown by seedlings to unidirectional light. Responses to light are coordinated by plant growth substances known as auxins. Explain the role of auxins in coordinating the response. For Examiner's Use Research workers in India tested the hypothesis that pigments in tomato seedlings detect blue light. They used a variety of tomato seedling that does not have the ability to make a certain pigment. These seedlings and a control group of seedlings were grown in the dark and then exposed to unidirectional blue light for 360 minutes. The scientists measured the degree of bending of the seedlings at intervals during the 360 minutes. Their results are shown in . time / min control group degree of bending no pigment Describe the results shown in . For Examiner's Use Suggest an explanation for the differences between the responses of the two groups of seedlings.
0610_s12_qp_32
THEORY
2012
Paper 3, Variant 2
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Questions Discovered
307