13.2. Investigation of limiting factors
A subsection of Biology, 9700, through 13. Photosynthesis
Listing 10 of 75 questions
In some ecosystems there are very low concentrations of nitrate ions in the soil. Some species of flowering plants are able to obtain the nitrogen that they need from other sources. Carnivorous plants have modified leaves that trap animals. Leaves of Drosera rotundifolia have hairs around each leaf that secrete a sticky solution. Insects, such as the one shown in , stick to this solution. The leaves curl around the insect and secrete enzymes to digest its body. Explain why D. rotundifolia can be considered to be both an autotroph and a heterotroph. In 1999, Dutch scientists discovered a new reaction, the anammox reaction, to add to the nitrogen cycle. They discovered the bacterium Brocadia anammoxidans that converts ammonia, nitrite ions and nitrate ions to nitrogen gas (N2) in anaerobic environments. The reaction carried out by these bacteria is thought to be responsible for the loss of a large quantity of nitrogen-containing compounds from marine ecosystems, such as the oceans. Suggest and explain the effect that this reaction has on marine ecosystems.
9700_w14_qp_21
THEORY
2014
Paper 2, Variant 1
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One way to estimate the rate of photosynthesis is to measure the rate of uptake of carbon dioxide. shows the relationship between light intensity and relative carbon dioxide uptake and production in a dicotyledonous plant. carbon dioxide uptake State two features of a dicotyledonous leaf that can affect the rate of photosynthesis. Explain the shape of the curve as light intensity increases from 0 to X. The uptake of radioactively-labelled carbon dioxide in chloroplasts was investigated. Three tubes, each containing different components of chloroplasts, were exposed to light. The results of the investigation are shown in Table 7.1. Table 7.1 tube contents uptake of radioactively- labelled carbon dioxide / counts per minute A stroma and grana 96 000 B stroma, ATP and reduced NADP 97 000 C stroma 4 000 Name the substance that combines with carbon dioxide in a chloroplast. Explain why the results in tube B are similar to those in tube A. Explain why the uptake in tube C was less than the uptake in tube B. Complete the following paragraph by using the most suitable words to fill in the gaps. In a photosystem, several hundred accessory pigment molecules surround a primary pigment molecule, called , in the membrane. The position of the primary pigment is also called the . Light energy is absorbed by the accessory pigments and passed on to the primary pigment. Electrons are excited to a higher energy level. They are emitted from the primary pigment and are captured by electron acceptors and eventually pass along the , producing ATP.
9700_w15_qp_41
THEORY
2015
Paper 4, Variant 1
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One way to estimate the rate of photosynthesis is to measure the rate of uptake of carbon dioxide. shows the relationship between light intensity and relative carbon dioxide uptake and production in a dicotyledonous plant. carbon dioxide uptake State two features of a dicotyledonous leaf that can affect the rate of photosynthesis. Explain the shape of the curve as light intensity increases from 0 to X. The uptake of radioactively-labelled carbon dioxide in chloroplasts was investigated. Three tubes, each containing different components of chloroplasts, were exposed to light. The results of the investigation are shown in Table 7.1. Table 7.1 tube contents uptake of radioactively- labelled carbon dioxide / counts per minute A stroma and grana 96 000 B stroma, ATP and reduced NADP 97 000 C stroma 4 000 Name the substance that combines with carbon dioxide in a chloroplast. Explain why the results in tube B are similar to those in tube A. Explain why the uptake in tube C was less than the uptake in tube B. Complete the following paragraph by using the most suitable words to fill in the gaps. In a photosystem, several hundred accessory pigment molecules surround a primary pigment molecule, called , in the membrane. The position of the primary pigment is also called the . Light energy is absorbed by the accessory pigments and passed on to the primary pigment. Electrons are excited to a higher energy level. They are emitted from the primary pigment and are captured by electron acceptors and eventually pass along the , producing ATP.
9700_w15_qp_42
THEORY
2015
Paper 4, Variant 2
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The light dependent stage of photosynthesis in a suspension of isolated chloroplasts can be investigated using the Hill reaction. Dichlorophenolindophenol (DCPIP) can be used to follow the process. DCPIP is a blue dye which turns colourless when it is reduced by accepting hydrogen and electrons. oxidised DCPIP reduced DCPIP blue colourless The natural hydrogen acceptor in chloroplasts that is replaced by DCPIP in the Hill reaction is NADP. Reduced NADP is then used in the light independent stage of photosynthesis. State the role of reduced NADP in the light independent stage. Predict and explain the effect on the concentration of RuBP in the chloroplasts if DCPIP becomes reduced instead of NADP. Explain the reasons for: the colour standard tube A covering the beaker containing the chloroplast-DCPIP mixture with foil. Table 2.1 shows the results of the experiment. Table 2.1 colour of filter wavelength of light / nm time taken to decolourise DCPIP / s rate of light dependent stage of photosynthesis / s–1 purple 27.0 blue 11.9 green 2.1 orange red 20.0 Complete Table 2.1 by calculating the rate of the light dependent stage of photosynthesis for the orange wavelength, using the formula: rate = 1000 t where t = time in seconds. With reference to Table 2.1, describe and explain the effect of light wavelength on the rate of the light dependent stage of photosynthesis.
9700_w17_qp_41
THEORY
2017
Paper 4, Variant 1
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The light dependent stage of photosynthesis in a suspension of isolated chloroplasts can be investigated using the Hill reaction. Dichlorophenolindophenol (DCPIP) can be used to follow the process. DCPIP is a blue dye which turns colourless when it is reduced by accepting hydrogen and electrons. oxidised DCPIP reduced DCPIP blue colourless The natural hydrogen acceptor in chloroplasts that is replaced by DCPIP in the Hill reaction is NADP. Reduced NADP is then used in the light independent stage of photosynthesis. State the role of reduced NADP in the light independent stage. Predict and explain the effect on the concentration of RuBP in the chloroplasts if DCPIP becomes reduced instead of NADP. Explain the reasons for: the colour standard tube A covering the beaker containing the chloroplast-DCPIP mixture with foil. Table 2.1 shows the results of the experiment. Table 2.1 colour of filter wavelength of light / nm time taken to decolourise DCPIP / s rate of light dependent stage of photosynthesis / s–1 purple 27.0 blue 11.9 green 2.1 orange red 20.0 Complete Table 2.1 by calculating the rate of the light dependent stage of photosynthesis for the orange wavelength, using the formula: rate = 1000 t where t = time in seconds. With reference to Table 2.1, describe and explain the effect of light wavelength on the rate of the light dependent stage of photosynthesis.
9700_w17_qp_43
THEORY
2017
Paper 4, Variant 3
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is a transverse section through a leaf from the maize plant, Zea mays. Maize is a C4 plant. C On , use label lines and letters to show: A – a cell in the epidermal layer B – a cell that contains PEP carboxylase. Identify the cell type labelled C in . C Explain how the leaf anatomy shown in adapts the C4 plant to maintain a high rate of photosynthesis at high temperatures. shows the results of an experiment comparing the rate of carbon dioxide uptake in a C3 plant (Chenopodium album) and a C4 plant (Amaranthus retroflexus) in high and low carbon dioxide (CO2) conditions. The rate of CO2 uptake is used to measure the rate of photosynthesis. temperature / °C rate of CO2 uptake / μmol m–2 s–1 Key C4 plant in high CO2 conditions C4 plant in low CO2 conditions C3 plant in high CO2 conditions C3 plant in low CO2 conditions Using , compare the rates of photosynthesis in high CO2 conditions in the C3 and C4 plants. Using , compare the rates of photosynthesis in low and high CO2 conditions in the C4 plant between 30 °C and 35 °C and suggest an explanation for this difference.
9700_w20_qp_41
THEORY
2020
Paper 4, Variant 1
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is a transverse section through a leaf from the maize plant, Zea mays. Maize is a C4 plant. C On , use label lines and letters to show: A – a cell in the epidermal layer B – a cell that contains PEP carboxylase. Identify the cell type labelled C in . C Explain how the leaf anatomy shown in adapts the C4 plant to maintain a high rate of photosynthesis at high temperatures. shows the results of an experiment comparing the rate of carbon dioxide uptake in a C3 plant (Chenopodium album) and a C4 plant (Amaranthus retroflexus) in high and low carbon dioxide (CO2) conditions. The rate of CO2 uptake is used to measure the rate of photosynthesis. temperature / °C rate of CO2 uptake / μmol m–2 s–1 Key C4 plant in high CO2 conditions C4 plant in low CO2 conditions C3 plant in high CO2 conditions C3 plant in low CO2 conditions Using , compare the rates of photosynthesis in high CO2 conditions in the C3 and C4 plants. Using , compare the rates of photosynthesis in low and high CO2 conditions in the C4 plant between 30 °C and 35 °C and suggest an explanation for this difference.
9700_w20_qp_43
THEORY
2020
Paper 4, Variant 3
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Questions Discovered
75