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A2 Respiration test. Total marks [40]. Glucose. X. Hexose phosphate. X. Hexose biphosphate. Triose phosphate. Z. Y. Pyruvate. Reduced Z. The diagram below shows some of the stages in glycolysis:. State precisely where this process occurs ……………………………………… [1]
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A2 Respiration test Total marks [40]
Glucose X Hexose phosphate X Hexose biphosphate Triose phosphate Z Y Pyruvate Reduced Z The diagram below shows some of the stages in glycolysis: • State precisely where this process occurs ………………………………………[1] • Identify substance X ……………………………………………..…………………[1] • Identify substance Y ………………………………………………………………..[1] • Briefly outline the fate of substance ‘reduced Z’ ………………………………… • ………………………………………………………………………………….. …… • ………………………………………………………………………………………..[2] in the cytoplasm ATP/phosphate group from ATP hydrogen Enters mitochondria; is (re-)oxidised; in the electron transport chain;
Carefully read the following account of aerobic respiration and then fill in the blanks: cytoplasm In the first stages of respiration which occurs in the ……………………………………….. of the cell, glucose is ……………………………….. to pyruvic acid. Glycolysis yields …………………………. and a reduced coenzyme. The pyruvic acid then combines with coenzyme A to form …………………………………….. which enters the Kreb’s cycle which occurs in the …………………………………………. of the ……………………………………………….. During these reactions hydrogen atoms are removed from a series of intermediate compounds by enzymes called …………………………………… . The hydrogen atoms are passed to carriers such as ……………………………………… . In the third stage of aerobic respiration, the carriers are alternately reduced and ……………………. as they gain and lose …………………………. . Energy is released and used to phosphorylate ADP, forming ………………………. . The hydrogen atoms finally combine with……………………….. to form ……………………………. . [13] oxidised ATP acetyl CoA matrix mitochondria dehydrogenases NAD/FAD oxidised electrons ATP oxygen water
Below is a diagram of a mitochondrion • Add labels where indicated. [5] matrix cristae b) any point on the inner membrane inner membrane outer membrane intermembrane space • Indicate on the diagram the precise site of the electron transport chain [1]
An experiment was carried out to measure the rate at which a sample of mitochondria used oxygen under different conditions. The mitochondria were placed in a well oxygenated liquid with a water potential equal to the water potential of their contents. At time A, an end-product of glycolysis was added to the liquid. At times B, C and D, ADP was added. The same amount of ADP was added each time. The results of this experiment are shown in the graph below: A B Oxygen concentration in the liquid C D 0 2 4 6 8 Time (mins)
a) Explain why the liquid used in the experiment should have the same water potential as the contents of the mitochondria ……………………………………………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………… [2] • to ensure there is no net movement of water/osmosis • that would cause a dilution/concentration of the matrix contents • or damage to mitochondria/bursting of organelle
pyruvate/pyruvic acid b) (i) State the name of the substance that was added at A ……………………………………………………………… [1] (ii) Name the two stages of the respiratory process that take place in the mitochondria …………………………………………………………… …………………………………………………………. [2] (iii) State the role of oxygen in these respiratory processes ……………………………………………………………… ……………………………………………………..………. [1] link reaction; Kreb’s cycle; ETC; oxidative phosphorylation to reoxidise the last substance/last cytochrome in the ETC
A B Oxygen concentration in the liquid C D 0 2 4 6 8 Time (mins) • oxidative phosphorylation can occur/ADP converted to ATP • which requires oxygen • to react with hydrogen to form water • less occurs at C than B because amount of reduced coenzymes is less/ORA c) Explain the result of adding ADP at the following points on the graph; • B and C …………………………………………………………………………… …………………………………………………………………………… …………………………………………………………………………… ………………………………………………………………………..… [3]
A B Oxygen concentration in the liquid C D 0 2 4 6 8 Time (mins) • no reaction occurs • due to lack of reduced NAD/FAD • which means lack of hydrogen ions/electrons for ETC (ii) D .............................................................................................................. ……………………………………………………………………..……… [2]
ethanol/ethanal • carbon dioxide Yeast cells can respire anaerobically using glucose as a substrate. (i) State the end products formed from the glucose if oxygen is not available to the yeast cells ……………………………………………………………………………………………… ……………………………………………………………………………………………… [2] (ii) Explain why ADP is required in anaerobic conditions ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… [3] • to form ATP • because glycolysis occurs • that requires additional ADP • to give a net gain of 2 ATP molecules