12.1. Energy
A subsection of Biology, 9700, through 12. Energy and respiration
Listing 10 of 34 questions
ATP and NAD both play important roles in respiration. Both compounds are nucleotides. represents the molecular structures of ATP and NAD. ATP NAD Using , compare the structures of ATP and NAD. ATP provides an immediate energy source for metabolic processes such as anabolic reactions. State two examples of anabolic reactions in a mammal that require ATP as an energy source. Name the type of chemical reaction by which ATP is made during the Krebs cycle. Outline the roles of NAD in the cytoplasm of a cell. Carbohydrates and lipids are used as respiratory substrates. Table 1.1 shows the energy values of carbohydrates and lipids. Table 1.1 respiratory substrate energy value / kJ g−1 carbohydrate 15.8 lipid 39.4 Explain why lipids have a higher energy value than carbohydrates.
9700_s16_qp_41
THEORY
2016
Paper 4, Variant 1
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ATP and NAD both play important roles in respiration. Both compounds are nucleotides. represents the molecular structures of ATP and NAD. ATP NAD Using , compare the structures of ATP and NAD. ATP provides an immediate energy source for metabolic processes such as anabolic reactions. State two examples of anabolic reactions in a mammal that require ATP as an energy source. Name the type of chemical reaction by which ATP is made during the Krebs cycle. Outline the roles of NAD in the cytoplasm of a cell. Carbohydrates and lipids are used as respiratory substrates. Table 1.1 shows the energy values of carbohydrates and lipids. Table 1.1 respiratory substrate energy value / kJ g−1 carbohydrate 15.8 lipid 39.4 Explain why lipids have a higher energy value than carbohydrates.
9700_s16_qp_43
THEORY
2016
Paper 4, Variant 3
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The respiratory quotient (RQ) is used to show what substrates are being metabolised in respiration. The RQ of a substrate may be calculated using the formula below: RQ = molecules of CO2 given out molecules of O2 taken in When the unsaturated fatty acid linoleic acid is respired aerobically the equation is: C18H32O2 + 25O2 ……… CO2 + 16H2O + energy Calculate how many molecules of carbon dioxide are produced when one molecule of linoleic acid is respired aerobically. answer Calculate the RQ for linoleic acid. answer Hummingbirds feed on nectar from flowers only during daylight hours. Nectar is rich in sugars. shows a hummingbird. Hummingbirds regulate their body temperature whereas butterflies do not regulate their body temperature. Explain briefly the effect of an increase in temperature on the rate of respiration of a butterfly.
9700_s09_qp_4
THEORY
2009
Paper 4, Variant 0
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All cells need ATP for energy-requiring processes in the body. shows the molecular structure of ATP. O– O O– P O O O– P O O O O O– P OH OH Y X N N N N H2N Name the base labelled X. Name the sugar labelled Y. State three reasons why ATP is ideal as an energy currency in all living organisms. ATP is produced in three stages of aerobic respiration. Complete the table below to show two products of each stage, other than ATP. stage products glycolysis 1. 2. Krebs cycle 1. 2. oxidative phosphorylation 1. 2. Carbohydrates and lipids are both used as respiratory substrates. Table 7.1 shows the energy values of carbohydrates and lipids. Table 7.1 respiratory substrate energy value / kJ g−1 carbohydrate 15.8 lipid 39.4 Explain why lipids have a higher energy value than carbohydrates. Respiration can be investigated by calculating the respiratory quotient (RQ). State how the RQ is calculated. Give the typical RQ values obtained from the respiration of carbohydrates and lipids. carbohydrate lipid Suggest what happens to the RQ value when respiration in yeast becomes anaerobic.
9700_s15_qp_42
THEORY
2015
Paper 4, Variant 2
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Outline the role of oxygen in aerobic respiration. Table 3.1 shows the results of some measurements of the energy released by different respiratory substrates and the water produced in the process. Table 3.1 respiratory substrate energy released / kJ mass of water produced / g per g of substrate per dm3 of oxygen consumed per g of substrate carbohydrate 17.4 20.9 0.56 lipid 39.3 19.6 1.07 protein 17.8 18.6 0.45 Describe and explain the differences in energy released by the three respiratory substrates. Suggest why more water is produced from the metabolism of lipid than from the other two substrates.
9700_w13_qp_43
THEORY
2013
Paper 4, Variant 3
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Questions Discovered
34