A Sports Scientist was investigating aerobic respiration in an athlete. The equation below summarises how ATP is produced, using energy from the oxidation of glucose, for this particular athlete.
glucose + oxygen + (ADP + Pi) → carbon dioxide + water + ATP
170 g 124.4 dm3 17.25 kg 124.4 dm3 107 g 17.25 kg
Calculate the mass of ATP produced per dm3 of oxygen for the athlete.
The Sports Scientist then decided to measure the volume of oxygen consumed and the mass of ATP produced by the athlete when they ran different length races.
Some of the results for the athlete are shown in the table below.
Length of race/m
Volume of oxygen consumed in cell respiration during race/dm3
Mass of ATP produced/kg
1 500
40
10 000
160
25 000
48.545
42 000
95.703
Complete the table by calculating the missing values.
Mitochondrial diseases in humans cause their mitochondria to malfunction. Individuals that suffer from mitochondrial diseases are only able to endure an intense exercise for a short period of time.
A group of researchers wanted to investigate ATP production in the preparation of isolated mitochondria taken from a person with mitochondrial disease. They suspended the mitochondria in an isotonic solution and added ADP, phosphate and a respiratory substrate. Oxygen was supplied throughout the preparation.
Researchers measured the rate of CO2 production by three groups of insects of the same species at 15 °C, 25 °C and 35 °C. The mean mass of each group of insects was also recorded. Their results can be seen in the table below.
Temperature / °C
Mean mass / g
Rate of CO2 release
/ µdm3 min-1
Rate of CO2 release per gram
/ µdm3 g-1 min-1
15
0.051
0.15
25
0.050
0.39
35
0.052
0.61
i)
Calculate the rate of carbon dioxide release per gram for each temperature in the table. Give your answer to two decimal places.
[1 mark]
ii)
Sketch a graph of your values against temperature.
A researcher used the apparatus shown below to measure the rate of respiration in yeast. The researcher placed the flask in a water bath with the bung open (so that the yeast culture reached a constant temperature), before adding the alkaline pyrogallol, inserting the bung and starting the investigation. In an alkaline solution, pyrogallol absorbs oxygen from the air.
When the researcher inserted the bung and began the experiment, the coloured liquid initially moved to the right. After a period of time, the coloured liquid slowed, stopped and reversed its direction, moving to the left.
Use the diagram above and your knowledge of respiration to explain these observations.
When the coloured liquid in part (a) moved to the left, the researcher measured that the coloured liquid moved 1.8 cm in 16 hours. The internal diameter of the capillary tubing was 1.3 mm. The volume of the capillary tubing is given by πr2l, where l = length.
Calculate the volume of gas produced and from this, the rate of gas production in mm3 hr–1. Show your working and give your answer to an appropriate number of significant figures.
The researcher then wanted to measure and compare the rate of aerobic respiration in different species of beetle (with different masses) using the experimental set-up shown below.
i)
Outline the different measurements that the researcher would need to take in order to calculate the aerobic respiration rate and to accurately compare these respiration rates between different beetle species.
[4 marks]
ii)
Suggest suitable units of respiration rate, based on the different measurements that the researcher would need to take.
The diagram below shows the process of glycolysis. Glycolysis is the first stage of respiration. It takes place in the cytoplasm of the cell and involves trapping glucose in the cell by phosphorylating the molecule and then splitting the glucose molecule in two.
One mark is available for clarity of communication throughout this question.
a)
Scientists investigated the effect of exercise on muscle fibres in mice. The mice were split into two groups. Group A undertook regular exercise for 8 weeks, Group B was not exercised. After 8 weeks the scientists compared how long each group of mice could carry out prolonged exercise.
i)
Identify which group was able to exercise for longer periods
[1 mark]
ii)
Using the idea of respiration, explain the scientists' findings.
The scientists then investigated the effect of cyanide on the uptake of oxygen in mitochondria isolated from mice cells. Cyanide acts as an inhibitor of several enzymes involved in respiration. The scientists compared the mice's mitochondria with mitochondria isolated from plant cells. They prepared a flask of suspension of each type of mitochondria and recorded the oxygen concentration in each flask over time.
After 10 minutes they added ADP and a respiratory substrate to each suspension.
After 20 minutes they added cyanide to each suspension.
Their results are shown in the graph below. During time A to C the results of the two flasks overlap.
i)
Describe the differences in results between lines C to D (mice mitochondria) and C to E (plant mitochondria).
