12.2. Respiration
A subsection of Biology, 9700, through 12. Energy and respiration
Listing 10 of 158 questions
ATP is used or produced at different stages in the respiration of glucose in aerobic conditions. Complete the table to show whether ATP is used or produced at each stage of respiration. Write either YES or NO in each box. stage of respiration ATP used ATP produced glycolysis link reaction Krebs cycle oxidative phosphorylation An experiment was carried out to investigate the effect of epicatechin on mitochondrial respiration in mice. Epicatechin is a naturally occurring compound in cocoa beans and so is present in chocolate. Two groups of mice, group A and group B, were used in this experiment. • Group A was given water containing epicatechin, twice a day for 15 days. • Group B was given water without epicatechin, twice a day for 15 days. After 15 days, the structure of mitochondria from striated muscle cells in both groups of mice was examined. The surface area of the inner membrane of the mitochondria was divided by the surface area of the outer membrane to obtain a ratio for each mouse. Table 4.1 shows the mean ratios for the two groups of mice. Table 4.1 group mean ratio A 2.0 : 1 B 1.7 : 1 The mice in group A were able to exercise longer than the mice in group B.
9700_s17_qp_41
THEORY
2017
Paper 4, Variant 1
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ATP is used or produced at different stages in the respiration of glucose in aerobic conditions. Complete the table to show whether ATP is used or produced at each stage of respiration. Write either YES or NO in each box. stage of respiration ATP used ATP produced glycolysis link reaction Krebs cycle oxidative phosphorylation An experiment was carried out to investigate the effect of epicatechin on mitochondrial respiration in mice. Epicatechin is a naturally occurring compound in cocoa beans and so is present in chocolate. Two groups of mice, group A and group B, were used in this experiment. • Group A was given water containing epicatechin, twice a day for 15 days. • Group B was given water without epicatechin, twice a day for 15 days. After 15 days, the structure of mitochondria from striated muscle cells in both groups of mice was examined. The surface area of the inner membrane of the mitochondria was divided by the surface area of the outer membrane to obtain a ratio for each mouse. Table 4.1 shows the mean ratios for the two groups of mice. Table 4.1 group mean ratio A 2.0 : 1 B 1.7 : 1 The mice in group A were able to exercise longer than the mice in group B.
9700_s17_qp_43
THEORY
2017
Paper 4, Variant 3
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At the end of glycolysis in mammalian muscle tissue, pyruvate is formed. Pyruvate can be further metabolised along two different pathways, pathway 1 and pathway 2. outlines the two pathways. pyruvate acetyl CoA lactate pathway 1 pathway 2 NAD reduced NAD reduced NAD NAD X State the condition under which pyruvate would be metabolised along pathway 2. Name compound X. Name the two types of reaction that are involved in pathway 1. Suggest a cell in a mammal that cannot carry out pathway 1. Give a reason for your answer. ATP is synthesised during glycolysis. Name the process by which ATP is synthesised. The rufous hummingbird, Selasphorus rufus, feeds on the nectar produced by flowers. Nectar is a liquid containing sugars. Hummingbirds hover to maintain a position next to a flower while they feed. This requires a lot of energy. is a rufous hummingbird. Hummingbirds that have not fed for some time have a respiratory quotient (RQ) value of 0.7. After feeding their RQ value is 1.0. Define the term respiratory quotient. Explain why a hummingbird that has not fed for some time has an RQ value of 0.7, while a hummingbird that has fed has an RQ value of 1.0. When animals exercise they can respire substrates obtained directly from their diet, as well as respiring substrates from energy stores. An investigation worked out the percentage of respiration that used substrates obtained directly from the diet of humans and hummingbirds as they exercised. shows the results of this investigation. human hummingbird percentage of respiration that used substrates obtained directly from the diet animal shows that hummingbirds have a higher percentage of respiration that uses substrates obtained directly from the diet. Calculate how many times greater this figure is for hummingbirds compared to humans. Show your working and write your answer to two decimal places. answer = Suggest the benefits to a hummingbird of obtaining most of its respiratory substrates from its diet while exercising.
9700_s20_qp_41
THEORY
2020
Paper 4, Variant 1
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All organisms respire to release energy from energy-rich molecules such as glucose. Anabolic reactions use energy. State two examples of anabolic reactions occurring in living organisms. Describe and explain the use of ATP in glycolysis. Some factory workers in the early 20th century were exposed to chemical X and experienced serious side-effects. Some of the effects of exposure to chemical X are: • decreased production of ATP • increased lipid metabolism, with weight loss • increased production of pyruvate and lactate • excess heat energy release, causing an increase in body temperature, which can be fatal. Chemical X increases the permeability of the inner mitochondrial membrane to protons (hydrogen ions), causing some protons to leak out into the matrix. Explain why people exposed to chemical X show: • decreased production of ATP • increased lipid metabolism. Suggest and explain why chemical X causes increased production of pyruvate and lactate. Suggest why excess heat energy is released.
9700_s21_qp_41
THEORY
2021
Paper 4, Variant 1
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shows the Krebs cycle and the reactions preceding it. State precisely where the Krebs cycle occurs in cells. Label on all the stages where decarboxylation reactions occur with a letter X. dehydrogenation reactions occur with a letter H. oxaloacetate(4C) acetyl CoA (2C) pyruvate (3C) 4C 4C 4C 4C 5C 6C citrate (6C) NAD reduced NAD NAD reduced NAD NAD reduced NAD NAD reduced NAD FAD reduced FAD ATP ADP Pi [T Explain how NAD is regenerated. State how the formation of ATP in the Krebs cycle differs from the formation of ATP in oxidative phosphorylation. [Total : 9]
9700_w05_qp_4
THEORY
2005
Paper 4, Variant 0
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During the process of glycolysis, glucose is converted by a series of steps into two molecules of pyruvate. outlines glycolysis. glucose (6C) hexose phosphate (6C) hexose bisphosphate (6C) triose phosphate (3C) intermediate (3C) pyruvate (3C) pyruvate (3C) intermediate (3C) triose phosphate (3C) step 1 step 2 step 3 step 4 step 5 NAD NAD reduced NAD reduced NAD 2ADP + 2Pi 2ADP + 2Pi 2ATP 2ATP With reference to , state the process occurring at: steps 1 and 2 step 3 step 4. Explain why glucose needs to be converted to hexose bisphosphate. Pyruvate can enter a mitochondrion when oxygen is present. Describe what happens to pyruvate in a yeast cell when oxygen is not present.
9700_w11_qp_41
THEORY
2011
Paper 4, Variant 1
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Questions Discovered
158