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12.2. Respiration
A subsection of Biology, 9700, through 12. Energy and respiration
Listing 10 of 158 questions
outlines some of the steps of glycolysis. glucose step 1 step 2 glucose 6–phosphate fructose 6–phosphate fructose 1, 6–bisphosphate triose phosphate triose phosphate pyruvate pyruvate step 3 step 4 step 5 State the precise location of glycolysis in the cell. With reference to : state the steps where phosphorylation occurs state the step where oxidation occurs name the type of reaction by which ATP is made during step 5. Some cancer cells have different metabolic requirements from normal cells. These cancer cells obtain most of their ATP from glycolysis, even if oxygen is available. State how the glucose and oxygen requirements of these cancer cells differ from normal cells.
9700_w18_qp_41
THEORY
2018
Paper 4, Variant 1
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outlines some of the steps of glycolysis. glucose step 1 step 2 glucose 6–phosphate fructose 6–phosphate fructose 1, 6–bisphosphate triose phosphate triose phosphate pyruvate pyruvate step 3 step 4 step 5 State the precise location of glycolysis in the cell. With reference to : state the steps where phosphorylation occurs state the step where oxidation occurs name the type of reaction by which ATP is made during step 5. Some cancer cells have different metabolic requirements from normal cells. These cancer cells obtain most of their ATP from glycolysis, even if oxygen is available. State how the glucose and oxygen requirements of these cancer cells differ from normal cells.
9700_w18_qp_43
THEORY
2018
Paper 4, Variant 3
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The results of investigations carried out on mitochondria show how the structure of a mitochondrion is related to its role in aerobic respiration. • Intact mitochondria (not damaged) were removed from cells. • A technique was used to remove the outer mitochondrial membrane, leaving the inner membrane intact. • The inner mitochondrial membrane was separated from the contents of the matrix so that both could be analysed. The removal of the outer membranes of mitochondria involves placing the organelles in pure water. This results in the rupture of the outer membrane. The inner mitochondrial membrane does not rupture and remains intact. Suggest and explain why the inner membrane of a mitochondrion remains intact when the organelle is placed in pure water. Name three molecules, other than coenzymes, that are found in the mitochondrial matrix and explain their role in aerobic respiration. The inner membrane contains a very high proportion of the molecule cardiolipin. Cardiolipin makes the membrane impermeable to some ions. Suggest why the inner membrane contains a very high proportion of cardiolipin. In further experiments it was found that, in an intact mitochondrion: • there is a membrane potential across the inner mitochondrial membrane, with the matrix having a negative charge • the transport of ATP, ADP and inorganic phosphate (Pis driven by the membrane potential across the inner membrane. shows the location of some inner membrane carrier proteins. + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – – – – – – – – – – – – ADP ADP ATP H+ intermembrane space carrier protein matrix outer membrane (freely permeable to ATP, ADP + Pinner membrane Pi Pi H+ ATP Reduced NAD and reduced FAD transfer hydrogen atoms to carriers located in the inner mitochondrial membrane. Explain how hydrogen atoms from reduced NAD and reduced FAD lead to a membrane potential forming across the inner mitochondrial membrane during oxidative phosphorylation. Suggest and explain how Pi is transported across the inner membrane of the mitochondrion into the matrix. Suggest the advantages of linking ATP transport to ADP transport across the inner membrane of the mitochondrion.
9700_w22_qp_41
THEORY
2022
Paper 4, Variant 1
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The results of investigations carried out on mitochondria show how the structure of a mitochondrion is related to its role in aerobic respiration. • Intact mitochondria (not damaged) were removed from cells. • A technique was used to remove the outer mitochondrial membrane, leaving the inner membrane intact. • The inner mitochondrial membrane was separated from the contents of the matrix so that both could be analysed. The removal of the outer membranes of mitochondria involves placing the organelles in pure water. This results in the rupture of the outer membrane. The inner mitochondrial membrane does not rupture and remains intact. Suggest and explain why the inner membrane of a mitochondrion remains intact when the organelle is placed in pure water. Name three molecules, other than coenzymes, that are found in the mitochondrial matrix and explain their role in aerobic respiration. The inner membrane contains a very high proportion of the molecule cardiolipin. Cardiolipin makes the membrane impermeable to some ions. Suggest why the inner membrane contains a very high proportion of cardiolipin. In further experiments it was found that, in an intact mitochondrion: • there is a membrane potential across the inner mitochondrial membrane, with the matrix having a negative charge • the transport of ATP, ADP and inorganic phosphate (Pis driven by the membrane potential across the inner membrane. shows the location of some inner membrane carrier proteins. + + + + + + + + + + + + + + + + + + + + + + + + – – – – – – – – – – – – – – – – – – – – – – ADP ADP ATP H+ intermembrane space carrier protein matrix outer membrane (freely permeable to ATP, ADP + Pinner membrane Pi Pi H+ ATP Reduced NAD and reduced FAD transfer hydrogen atoms to carriers located in the inner mitochondrial membrane. Explain how hydrogen atoms from reduced NAD and reduced FAD lead to a membrane potential forming across the inner mitochondrial membrane during oxidative phosphorylation. Suggest and explain how Pi is transported across the inner membrane of the mitochondrion into the matrix. Suggest the advantages of linking ATP transport to ADP transport across the inner membrane of the mitochondrion.
9700_w22_qp_43
THEORY
2022
Paper 4, Variant 3
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During aerobic respiration, cells respire substrates such as glucose to produce ATP. Some events that occur during aerobic respiration are: • The respiratory substrate breaks down into smaller and smaller molecules. These series of reactions are described as catabolism. • Coenzymes take part in various reactions. In some reactions, coenzymes are reduced or oxidised. • Carbon dioxide is released. Aerobic respiration occurs in four successive stages: glycolysis (G), link reaction (LR), Krebs cycle (KC) and oxidative phosphorylation (OP). Complete Table 3.1 to show which events occur in each stage of aerobic respiration. Use a tick (✓) to show that the event does occur or a cross (✗) to show that the event does not occur. Table 3.1 event stage G LR KC OP catabolism coenzyme is reduced or oxidised a coenzyme forms a covalent bond with a respiratory intermediate carbon dioxide is released A new hand‑held technological device shows the main type of respiratory substrate being used in the cells of a person. The device consists of a carbon dioxide sensor and air‑flow meter. The person inhales through the device for a fixed time and then exhales into it. The device calculates the respiratory quotient (RQ) value to show whether the cells are mainly respiring carbohydrates or lipids. Explain how the device calculates the RQ value and how this shows whether the cells are mainly respiring carbohydrates or lipids. … … … … … … State the difference in the relative energy values of carbohydrates and lipids as respiratory substrates, and explain the reasons for the difference. … … … … … …
9700_w24_qp_41
THEORY
2024
Paper 4, Variant 1
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During aerobic respiration, cells respire substrates such as glucose to produce ATP. Some events that occur during aerobic respiration are: • The respiratory substrate breaks down into smaller and smaller molecules. These series of reactions are described as catabolism. • Coenzymes take part in various reactions. In some reactions, coenzymes are reduced or oxidised. • Carbon dioxide is released. Aerobic respiration occurs in four successive stages: glycolysis (G), link reaction (LR), Krebs cycle (KC) and oxidative phosphorylation (OP). Complete Table 3.1 to show which events occur in each stage of aerobic respiration. Use a tick (✓) to show that the event does occur or a cross (✗) to show that the event does not occur. Table 3.1 event stage G LR KC OP catabolism coenzyme is reduced or oxidised a coenzyme forms a covalent bond with a respiratory intermediate carbon dioxide is released A new hand‑held technological device shows the main type of respiratory substrate being used in the cells of a person. The device consists of a carbon dioxide sensor and air‑flow meter. The person inhales through the device for a fixed time and then exhales into it. The device calculates the respiratory quotient (RQ) value to show whether the cells are mainly respiring carbohydrates or lipids. Explain how the device calculates the RQ value and how this shows whether the cells are mainly respiring carbohydrates or lipids. … … … … … … State the difference in the relative energy values of carbohydrates and lipids as respiratory substrates, and explain the reasons for the difference. … … … … … …
9700_w24_qp_43
THEORY
2024
Paper 4, Variant 3
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Isolated mitochondria were used to investigate respiration. • Mitochondria were extracted from respiring mammalian cells and incubated in a buffer solution. • Pyruvate and inorganic phosphate (Pwere added at time zero. • ADP was added one minute later. • The oxygen concentration of the buffer solution containing mitochondria was monitored throughout the investigation. The results of the investigation are shown in . time / min phase A phase B phase C pyruvate and Pi added ADP added oxygen concentration of buffer solution containing mitochondria Suggest why the line of the graph in is steeper during phase B than during phase A. Suggest why the line of the graph starts to level out in phase C. Some plants, such as rice, grow with their roots submerged in water. shows a group of rice plants. Explain how rice is adapted to grow with its roots submerged in water.
9700_m19_qp_42
THEORY
2019
Paper 4, Variant 2
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Questions Discovered
158