page 04 4. Shrews are small mammals. The graph shows the relationship between body mass and oxygen consumption of shrews at two environmental temperatures. Oxygen consumption (cm³/g of body mass/hour) Body mass (g) Key 10 °C 20 °C 0 4 8 12 16 20 0 4 8 12 16 Which of the following statements about this graph is correct? A Shrews of greater mass consumed less oxygen. B The optimum temperature for oxygen consumption was 10 °C. C As environmental temperature increased oxygen consumption decreased. D At 10 °C a 16 g shrew consumed 6·2 cm3 of oxygen/g of body mass/hour. 5. Yeast cells contain the enzyme catalase which breaks down hydrogen peroxide to produce oxygen. An experiment was carried out into the effect of lead nitrate concentration on the activity of catalase. Six flasks were set up. Each contained 25 cm3 of hydrogen peroxide and 10 cm3 of yeast suspension. 10 cm3 of a different concentration of lead nitrate was then added to each flask. The volume of oxygen produced after 15 minutes was measured. Identify the independent variable in this experiment. A Volume of lead nitrate B Volume of oxygen produced C Activity of catalase D Concentration of lead nitrate