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A2 Respiration test Total marks [40]. The diagram below shows some of the stages in glycolysis: Glucose Hexose phosphate Hexose biphosphate Triose phosphate.

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Presentation on theme: "A2 Respiration test Total marks [40]. The diagram below shows some of the stages in glycolysis: Glucose Hexose phosphate Hexose biphosphate Triose phosphate."— Presentation transcript:

1 A2 Respiration test Total marks [40]

2 The diagram below shows some of the stages in glycolysis: Glucose Hexose phosphate Hexose biphosphate Triose phosphate Pyruvate X X Y Z Reduced Z 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;

3 Carefully read the following account of aerobic respiration and then fill in the blanks: 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] cytoplasm oxidisedATP acetyl CoA matrix mitochondria dehydrogenases NAD/FAD oxidised electrons ATP oxygen water

4 Below is a diagram of a mitochondrion a)Add labels where indicated.[5] b)Indicate on the diagram the precise site of the electron transport chain [1] cristae matrix inner membrane intermembrane space outer membrane b) any point on the inner membrane

5 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: Time (mins) Oxygen concentration in the liquid A B D C

6 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

7 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] pyruvate/pyruvic acid link reaction; Kreb’s cycle; ETC; oxidative phosphorylation to reoxidise the last substance/last cytochrome in the ETC

8 c) Explain the result of adding ADP at the following points on the graph; (i)B and C …………………………………………………………………………… ………………………………………………………………………..… [3] Time (mins) Oxygen concentration in the liquid A B D C 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

9 (ii) D ……………………………………………………………………..……… [2] no reaction occurs due to lack of reduced NAD/FAD which means lack of hydrogen ions/electrons for ETC Time (mins) Oxygen concentration in the liquid A B D C

10 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] ethanol/ethanal carbon dioxide to form ATP because glycolysis occurs that requires additional ADP to give a net gain of 2 ATP molecules


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