12. Energy and respiration
A section of Biology, 9700
Listing 10 of 192 questions
Outline the process of glycolysis in a mammalian cell. Within a mammalian cell, ATP can be produced in a number of ways, including: • substrate level phosphorylation during the Krebs cycle • oxidative phosphorylation. Table 7.1 compares both processes. Complete Table 7.1. Use a tick () if the statement is correct or a cross () if the statement is incorrect. The first row has been done for you. Table 7.1 statement substrate level phosphorylation oxidative phosphorylation enzymes are involved   occurs in cytoplasm occurs in mitochondria channel proteins are involved An investigation into the RQ values of germinating maize seeds was carried out. • A sample of maize seeds was soaked in water for one hour. • The mean RQ value of some of the seeds was then calculated and the remaining seeds were then planted in soil. • After 12 hours, the mean RQ value of some of the planted seeds was calculated. • The remaining seeds were allowed to germinate and grow into seedlings. • After 21 days, the mean RQ value of some of the seedlings was calculated. Table 7.2 shows the results of the investigation. Table 7.2 stage of germination and growth mean RQ seeds soaked in water 5.6 seeds after 12 hours in the soil 0.8 seedlings after 21 days 1.0 Suggest an explanation for each of the RQ values shown in Table 7.2. seeds soaked in water seeds after 12 hours in the soil seedlings after 21 days
9700_s15_qp_43
THEORY
2015
Paper 4, Variant 3
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When a dormant seed absorbs water it will start to germinate and its rate of respiration will increase. Name the plant growth regulator involved in the initiation of germination of seeds. A respirometer can be used to measure the rate of respiration of germinating seeds. shows a respirometer. coloured liquid graduated tube mesh potassium hydroxide solution pea seed State the role of potassium hydroxide solution in the use of a respirometer. As respiration takes place, oxygen is used by the seeds and the coloured liquid moves down the tube. Describe the role of oxygen in aerobic respiration. Respirometers, as shown in , were used to investigate the effect of temperature on the rate of respiration of germinating pea seeds. Four respirometers, A, B, C and D were set up: • A and B in a water-bath maintained at 10 °C. • C and D in a water-bath maintained at 25 °C. • A and C each contained 30 germinating pea seeds. • B and D each contained glass beads with a total volume equivalent to 30 pea seeds. • The respirometers were left in the water-baths for 10 minutes. • In each respirometer the position of the coloured liquid in the graduated tube was then marked (time 0 minutes). • After 5 minutes the distance moved by the coloured liquid was measured. • The volume of oxygen taken up was calculated for each respirometer. • This was repeated after 10, 15 and 20 minutes. shows the results of the experiment. 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 C A B and D time / minutes volume of oxygen taken up / cm3 Suggest why the respirometers were left for 10 minutes before measurements were made. Suggest why respirometers B and D were used in this investigation. Calculate the rate of oxygen uptake in cm3 per minute for respirometer C between 5 and 20 minutes. Give your answer to two significant figures. Show your working. answer cm3 min–1 Explain why there is an increased rate of respiration of germinating pea seeds between 10 °C and 25 °C. Suggest why carrying out the experiment with germinating seeds at 50 °C could result in a lower rate of respiration than at 25 °C.
9700_w16_qp_41
THEORY
2016
Paper 4, Variant 1
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When a dormant seed absorbs water it will start to germinate and its rate of respiration will increase. Name the plant growth regulator involved in the initiation of germination of seeds. A respirometer can be used to measure the rate of respiration of germinating seeds. shows a respirometer. coloured liquid graduated tube mesh potassium hydroxide solution pea seed State the role of potassium hydroxide solution in the use of a respirometer. As respiration takes place, oxygen is used by the seeds and the coloured liquid moves down the tube. Describe the role of oxygen in aerobic respiration. Respirometers, as shown in , were used to investigate the effect of temperature on the rate of respiration of germinating pea seeds. Four respirometers, A, B, C and D were set up: • A and B in a water-bath maintained at 10 °C. • C and D in a water-bath maintained at 25 °C. • A and C each contained 30 germinating pea seeds. • B and D each contained glass beads with a total volume equivalent to 30 pea seeds. • The respirometers were left in the water-baths for 10 minutes. • In each respirometer the position of the coloured liquid in the graduated tube was then marked (time 0 minutes). • After 5 minutes the distance moved by the coloured liquid was measured. • The volume of oxygen taken up was calculated for each respirometer. • This was repeated after 10, 15 and 20 minutes. shows the results of the experiment. 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 C A B and D time / minutes volume of oxygen taken up / cm3 Suggest why the respirometers were left for 10 minutes before measurements were made. Suggest why respirometers B and D were used in this investigation. Calculate the rate of oxygen uptake in cm3 per minute for respirometer C between 5 and 20 minutes. Give your answer to two significant figures. Show your working. answer cm3 min–1 Explain why there is an increased rate of respiration of germinating pea seeds between 10 °C and 25 °C. Suggest why carrying out the experiment with germinating seeds at 50 °C could result in a lower rate of respiration than at 25 °C.
9700_w16_qp_42
THEORY
2016
Paper 4, Variant 2
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A respirometer can be used to measure the respiration rate of small invertebrates such as the common woodlouse, Oniscus asellus. shows a common woodlouse. shows a respirometer. coloured liquid graduated tube mesh solution X position of woodlice Name solution X. The respirometer can be used to measure the effect of temperature on the rate of respiration of organisms. Suggest one factor that would need to be taken into account when using woodlice rather than germinating seeds. As respiration takes place, oxygen is used by the woodlice and the coloured liquid moves down the graduated tube. Name the stage of aerobic respiration where oxygen is used. A respirometer as shown in was used to investigate the effect of temperature on the rate of respiration of woodlice. • A student set up a respirometer containing 5 woodlice. • The respirometer was placed in a water-bath maintained at 15 °C. • The respirometer was left for 10 minutes to equilibrate. • After a further 15 minutes the distance moved by the coloured liquid was measured. • The volume of oxygen used by the woodlice was then calculated. • The experiment was repeated, using the same woodlice and respirometer, at 25 °C. The results are shown in Table 8.1. Table 8.1 temperature / °C volume of oxygen used / cm3 rate of oxygen uptake / cm3 min–1 0.18 0.42 Complete Table 8.1 by calculating the rates of oxygen uptake at 15 °C and 25 °C. Explain the difference in the rates of oxygen uptake at 15 °C and 25 °C. In anaerobic conditions, the pyruvate formed in glycolysis is converted to ethanol in yeast cells and to lactate in mammalian tissue. Compare the pathways by which pyruvate is converted to ethanol or to lactate.
9700_w16_qp_43
THEORY
2016
Paper 4, Variant 3
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During a sporting event, an athlete carries out respiration in aerobic conditions. Complete Table 2.1 to state the precise locations within a muscle cell of glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation. Table 2.1 process precise location glycolysis link reaction Krebs cycle oxidative phosphorylation In a muscle cell, molecules of glucose are phosphorylated at the start of glycolysis. Suggest why the phosphorylated glucose molecules cannot diffuse out of the cell. Sometimes an athlete will need to carry out respiration in anaerobic conditions to produce ATP. Explain why the respiration of glucose in anaerobic conditions produces less ATP than in aerobic conditions. For a short time after exercise, a person continues to breathe more heavily than at rest to take in more oxygen than normal. Explain the use of this extra oxygen.
9700_m17_qp_42
THEORY
2017
Paper 4, Variant 2
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The initial stages of respiration convert one molecule of glucose into two molecules of a 3C compound. State the name given to these initial stages where these stages occur in cells the total number of ATP molecules formed during these stages. Most of the ATP formed in respiration is produced within the mitochondria by oxidative phosphorylation. State the location, in the mitochondrion, of oxidative phosphorylation. Outline the process of oxidative phosphorylation. In an investigation, mammalian liver cells were homogenised (broken up) and the resulting homogenate centrifuged. Samples of the complete homogenate and samples containing only nuclei, only ribosomes, only mitochondria or only the remaining cytosol were incubated with: glucose pyruvate glucose and cyanide pyruvate and cyanide Cyanide inhibits oxidative phosphorylation. After incubation the presence or absence of carbon dioxide and lactate in each sample was determined. The results are summarised in Table 7.1. Table 7.1 samples of homogenate complete only nuclei only ribosomes only mitochondria only cytosol carbon dioxide lactate carbon dioxide lactate carbon dioxide lactate carbon dioxide lactate carbon dioxide lactate 1 glucose ✓ ✓ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✓ 2 pyruvate ✓ ✓ ✘ ✘ ✘ ✘ ✓ ✘ ✘ ✓ 3 glucose and cyanide ✘ ✓ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✓ 4 pyruvate and cyanide ✘ ✓ ✘ ✘ ✘ ✘ ✘ ✘ ✘ ✓ ✘ = absent ✓ = present With reference to Table 7.1, name the two organelles not involved in respiration. 1. 2. Explain why carbon dioxide is produced when mitochondria are incubated with pyruvate but not when they are incubated with glucose. Explain why, in the presence of cyanide, lactate is produced but carbon dioxide is not.
9700_s10_qp_41
THEORY
2010
Paper 4, Variant 1
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The Krebs cycle occurs in the matrix of the mitochondrion. outlines the steps of the Krebs cycle. acetyl CoA ( 2C ) CO2 CO2 2H 2H K K intermediates ( 5C ) K reduced FAD ATP 2H 2H citrate ( 6C ) L ( 4C ) With reference to name the process occurring at: 1 and 3 2, 4, 6 and 7 Name the compounds K and L. K L Most of the hydrogen atoms that are released by the Krebs cycle will take part in oxidative phosphorylation on the cristae of the mitochondria. Outline the process of oxidative phosphorylation.
9700_s11_qp_42
THEORY
2011
Paper 4, Variant 2
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Questions Discovered
192