Question 1
Unit 5 style
Which RQ would you expect from an organism respiring only glucose aerobically?
- 0.5
- 0.7
- 0.9
- 1.0
Show mark scheme for question 1
Question 2
Unit 5 style
A student measured the gas exchange of germinating sunflower seeds. In 20 minutes the seeds used 52 cm³ of oxygen and produced 38 cm³ of carbon dioxide. Calculate the respiratory quotient.
Show mark scheme for question 2
Question 3
Unit 5 style
Explain why the RQ for the respiration of lipid is lower than the RQ for the respiration of carbohydrate.
Show mark scheme for question 3
Question 4
Unit 5 style
Describe how a redox indicator can be used to compare the rate of respiration of yeast at different temperatures.
Show mark scheme for question 4
Question 5
Unit 6 style
In a yeast and methylene blue experiment, a student added a layer of oil to the surface of each tube. Explain why this improves the results, and suggest a suitable control.
Show mark scheme for question 5
Question 6
Unit 5 style
A respirometer containing germinating peas has a capillary tube of internal radius 0.4 mm. With potassium hydroxide in the apparatus, the fluid moved 30 mm in 10 minutes. Without potassium hydroxide, it moved 10 mm in 10 minutes. Calculate (a) the rate of oxygen uptake in mm³ min⁻¹ and (b) the RQ.
Show mark scheme for question 6
Question 7
Unit 6 style
In a respirometer experiment using woodlice, a control tube containing glass beads of the same volume was used. Explain the purpose of the control tube and give one safety precaution.