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12. Energy and respiration
A section of Biology, 9700
Listing 10 of 192 questions
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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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_43
THEORY
2014
Paper 4, Variant 3
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is an outline diagram showing two stages of aerobic respiration. pyruvate (3C) acetyl coenzyme A (2C) oxaloacetate (4C) ATP ADP + Pi intermediate compounds (5C) stage Y reduced Q reduced Q reduced R step 1 step 2 step 3 Q Q reduced Q Q R citrate (6C) stage X With reference to : name stage X state the precise location of stage Y state the numbered steps in stage Y in which decarboxylation occurs name the type of reaction by which ATP is made during step 3 name substances Q and R. Uncontrolled cell division can lead to a cancerous tumour. Many cancer cells break down the amino acid glutamine and convert it to a 5-carbon intermediate compound, which is shown in . Suggest how the breakdown of glutamine can lead to the production of ATP in a cancer cell, other than that directly produced during step 3.
9700_s18_qp_42
THEORY
2018
Paper 4, Variant 2
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The link reaction and Krebs cycle take place in the mitochondrion. The main stages of the link reaction and Krebs cycle are listed in Table 4.1. They are not listed in the correct order. Table 4.1 stage description of stage A acetyl group combines with coenzyme A to form acetyl CoA B citrate is formed C hydrogen atoms are accepted by NAD and FAD D oxaloacetate is regenerated E pyruvate enters the mitochondrial matrix F acetyl group is formed G acetyl CoA enters Krebs cycle H ATP is made by substrate-linked phosphorylation I pyruvate is decarboxylated and dehydrogenated J acetyl CoA combines with oxaloacetate K citrate is decarboxylated and dehydrogenated Complete Table 4.2 to show the correct order of the stages. Three of the stages have been done for you. Table 4.2 correct order letter of stage E J D Outline the role of NAD in respiration in aerobic conditions. Carbon dioxide is removed from compounds in the link reaction and Krebs cycle by decarboxylation. State the total number of molecules of carbon dioxide removed in the link reaction and Krebs cycle for each molecule of glucose respired. In a mammal, carbon dioxide diffuses from cells into the blood to be transported to the lungs. Suggest why carbon dioxide is transported in the blood mainly as hydrogen carbonate ions and not as carbonic acid.
9700_s19_qp_41
THEORY
2019
Paper 4, Variant 1
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Oxidative phosphorylation takes place in the mitochondrion. Table 8.1 shows the different stages of oxidative phosphorylation. The stages are not listed in the correct order. Table 8.1 stage description of stage Q protons diffuse through the membrane proteins into the matrix R a proton gradient is set up across the crista membrane 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 8.2 to show the correct order of the stages. Two of the stages have been completed for you. Table 8.2 correct order letter of stage V R State the precise location in a mitochondrion of each of the following. ATP synthase Krebs cycle electron transport chain coenzyme A pyruvate
9700_s19_qp_42
THEORY
2019
Paper 4, Variant 2
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Table 8.1 shows some of the stages of glycolysis and respiration in anaerobic conditions in yeast. The stages are not listed in the correct order. Table 8.1 stage description of stage A triose phosphate is dehydrogenated by NAD B pyruvate is decarboxylated C ethanal is formed D ethanol is formed E glucose is phosphorylated by ATP F pyruvate is formed G ethanal is reduced by alcohol dehydrogenase H fructose bisphosphate is formed I ATP is made by substrate-linked phosphorylation Complete Table 8.2 to show the correct order of the stages. One stage has been completed for you. Table 8.2 correct order letter of stage F Yeast respires glucose in aerobic and anaerobic conditions. Explain why less ATP is produced when yeast respires in anaerobic conditions compared to when yeast respires in aerobic conditions.
9700_s19_qp_43
THEORY
2019
Paper 4, Variant 3
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Respiration is a process that results in the synthesis of ATP. The ATP can be used within the cell for energy-requiring reactions and processes. There are four stages in aerobic respiration: glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation. The ATP synthesised in respiration can be used to make larger and more complex biological molecules from smaller molecules. Name the type of reaction that occurs when larger more complex biological molecules are made from smaller molecules. The first part of glycolysis uses ATP. Explain why ATP is needed in the first part of glycolysis. State the precise locations of substrate-linked phosphorylation reactions in aerobic respiration. Explain what happens to pyruvate in the link reaction in aerobic respiration. Chemiosmosis is a process that occurs in mitochondria during aerobic respiration and in chloroplasts during photosynthesis. Describe the differences between the process of chemiosmosis in mitochondria and the process of chemiosmosis in chloroplasts.
9700_s22_qp_41
THEORY
2022
Paper 4, Variant 1
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Questions Discovered
192