12. Energy and respiration
A section of Biology, 9700
Listing 10 of 192 questions
An experiment was carried out to investigate the effect of temperature on the rate of oxygen consumption of the lizard, Sauromalus hispidus. The body temperature of a lizard varies with environmental temperature. Several lizards were fitted with small, airtight masks that covered their heads. Air was supplied inside the mask through one tube, and collected through another. The differences between oxygen concentrations in the air supplied for inhalation and the exhaled air enabled the researchers to measure the rate of oxygen consumption of the lizards. The rate of oxygen consumption of each lizard was measured when it was at rest and when it was running. Measurements were made at different temperatures ranging from 15 °C to 40 °C. shows the results. 0.01 0.10 1.00 temperature / °C O2 consumption / cm3 g–1 hour–1 (log scale) at rest running Running requires rapid use of ATP by muscle cells in the legs and heart of a lizard. With reference to the events occurring inside a mitochondrion, explain why a faster use of ATP requires a greater rate of oxygen consumption. Explain the effect of temperature on the rate of oxygen consumption in Sauromalus when at rest. The researchers also measured the oxygen debt that was built up when a lizard was running. They measured this for two species of lizard, Sauromalus hispidus and Varanus gouldi, at six different temperatures. The results are shown in Table 4.1. Table 4.1 temperature / °C Sauromalus oxygen debt / cm3 O2 kg−1 70.3 81.3 93.0 102.0 118.0 154.0 Varanus oxygen debt / cm3 O2 kg−1 62.0 72.2 78.5 87.9 96.7 102.0 The oxygen debts were found by using the masks described in . Suggest what measurements were taken, and how these measurements were used to calculate the oxygen debt. Compare the oxygen debt built up by a running Varanus with that of a running Sauromalus. Varanus is a fast-moving carnivore. Sauromalus is a slow-moving herbivore. Explain how the results in Table 4.1 indicate that Varanus is well-adapted for its mode of life. Most lizards, including Sauromalus, have very simple lungs with no alveoli. Varanus, however, has lungs that are more like those of mammals, containing large numbers of air sacs similar to the alveoli of human lungs. Suggest how this difference could account for the differences in the oxygen debts of Sauromalus and Varanus shown in Table 4.1.
9700_s13_qp_41
THEORY
2013
Paper 4, Variant 1
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An experiment was carried out to investigate the effect of temperature on the rate of oxygen consumption of the lizard, Sauromalus hispidus. The body temperature of a lizard varies with environmental temperature. Several lizards were fitted with small, airtight masks that covered their heads. Air was supplied inside the mask through one tube, and collected through another. The differences between oxygen concentrations in the air supplied for inhalation and the exhaled air enabled the researchers to measure the rate of oxygen consumption of the lizards. The rate of oxygen consumption of each lizard was measured when it was at rest and when it was running. Measurements were made at different temperatures ranging from 15 °C to 40 °C. shows the results. 0.01 0.10 1.00 temperature / °C O2 consumption / cm3 g–1 hour–1 (log scale) at rest running Running requires rapid use of ATP by muscle cells in the legs and heart of a lizard. With reference to the events occurring inside a mitochondrion, explain why a faster use of ATP requires a greater rate of oxygen consumption. Explain the effect of temperature on the rate of oxygen consumption in Sauromalus when at rest. The researchers also measured the oxygen debt that was built up when a lizard was running. They measured this for two species of lizard, Sauromalus hispidus and Varanus gouldi, at six different temperatures. The results are shown in Table 4.1. Table 4.1 temperature / °C Sauromalus oxygen debt / cm3 O2 kg−1 70.3 81.3 93.0 102.0 118.0 154.0 Varanus oxygen debt / cm3 O2 kg−1 62.0 72.2 78.5 87.9 96.7 102.0 The oxygen debts were found by using the masks described in . Suggest what measurements were taken, and how these measurements were used to calculate the oxygen debt. Compare the oxygen debt built up by a running Varanus with that of a running Sauromalus. Varanus is a fast-moving carnivore. Sauromalus is a slow-moving herbivore. Explain how the results in Table 4.1 indicate that Varanus is well-adapted for its mode of life. Most lizards, including Sauromalus, have very simple lungs with no alveoli. Varanus, however, has lungs that are more like those of mammals, containing large numbers of air sacs similar to the alveoli of human lungs. Suggest how this difference could account for the differences in the oxygen debts of Sauromalus and Varanus shown in Table 4.1.
9700_s13_qp_43
THEORY
2013
Paper 4, Variant 3
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Yeast cells sometimes carry out anaerobic respiration. outlines the process of anaerobic respiration in yeast cells. S\UXYDWH FRPSRXQG; FRPSRXQG: FRPSRXQG X Y State two differences between anaerobic respiration in yeast cells and anaerobic respiration in human muscle cells. Dinitrophenol (DNP) is a compound used as a herbicide. DNP inhibits respiration by interfering with the formation of the proton gradient between mitochondrial membranes. When DNP was added to isolated mitochondria the following observations were made: • fewer ATP molecules were produced • more heat energy was released • the uptake of oxygen remained constant. Suggest explanations for these observations. fewer ATP molecules produced more heat energy released constant oxygen uptake
9700_w15_qp_43
THEORY
2015
Paper 4, Variant 3
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is an electron micrograph of part of a eukaryotic cell. X Y G mitochondrion ×47 000 State how it is possible to deduce that is a transmission electron micrograph and not a scanning electron micrograph. Both the Golgi body and the rough endoplasmic reticulum are part of the internal network of membranes in cells. Outline structural features shown in that identify G as the Golgi body and not the rough endoplasmic reticulum. Calculate the actual diameter, X–Y, of the mitochondrion labelled in . Write down the formula that you will use to make your calculation. Give your answer to the nearest whole nanometre . formula actual diameter nm The inner and outer membranes of the mitochondrion have a fluid mosaic structure similar to other cell membranes. They are both approximately 6 to 7 nanometres thick. Outline the fluid mosaic model of membrane structure. There is space below for a diagram. The inner and outer membranes of the mitochondrion differ in the detail of their membrane components. The inner membrane is also much less permeable than the outer membrane. Suggest one way in which the structure of the inner membrane may differ from that of the outer membrane to produce a less permeable inner membrane.
9700_m18_qp_22
THEORY
2018
Paper 2, Variant 2
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is an electron micrograph of a mitochondrion. 0.7 +m A State the function of mitochondria. Name structure A. Calculate the magnification of the image in . Show your working. magnification × Explain why the light microscope could not be used to produce the image in . Scientists think that mitochondria were once prokaryotes. The evidence for this is that mitochondria have features in common with prokaryotes. State two features that mitochondria have in common with prokaryotes. 1. 2.
9700_w15_qp_21
THEORY
2015
Paper 2, Variant 1
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Questions Discovered
192