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 | |

1. (a)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 | | [2]
2. (b)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. With reference to Table 4.1, explain why the mice in group A were able to exercise for longer than the mice in group B.[5]