12.2. Respiration
A subsection of Biology, 9700, through 12. Energy and respiration
Listing 10 of 158 questions
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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In aerobic respiration, ATP is synthesised by substrate-linked reactions and by oxidative phosphorylation. Outline the process of oxidative phosphorylation. In an experiment on respiration, two different populations of yeast cells were used: A and B. • Yeast cells in population A had no mitochondria in their cells. • Yeast cells in population B did have mitochondria in their cells. Both populations were provided with glucose in solution and the concentration of ATP was measured every minute for seven minutes. shows the results of the experiment. time / min population A population B ATP concentration / μmol dm–3 Describe and explain the difference in results between population A and population B, as shown in .
9700_m22_qp_42
THEORY
2022
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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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_43
THEORY
2011
Paper 4, Variant 3
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A mitochondrion contains DNA and ribosomes and is the organelle in which aerobic respiration takes place. Suggest the functions of the DNA and ribosomes in a mitochondrion. Oxidative phosphorylation takes place in the mitochondrion. Different stages of oxidative phosphorylation are listed below. They are not listed in the correct order. stage description of stage Q protons diffuse through the channel protein into the matrix R a proton gradient is set up across the crista S hydrogen atoms split into protons and electrons T protons combine with electrons and oxygen atoms to form water U electrons are passed from carrier to carrier V reduced NAD releases hydrogen atoms to cytochrome carriers W energy from electron transfer is used to pump protons into the intermembrane space X ATP synthase produces ATP Complete Table 8.1 to show the correct order of the stages. Two of the stages have been done for you. Table 8.1 correct order letter of stage V R ATP can be converted to ADP and inorganic phosphate by the enzyme ATPase. State the type of reaction taking place. Some parasitic worms, such as tapeworms, live in a mammalian gut where there is no oxygen. Suggest how a tapeworm produces ATP in this environment.
9700_s14_qp_41
THEORY
2014
Paper 4, Variant 1
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Questions Discovered
158