Oxidative phosphorylation and respiratory quotientEdexcel International A Level Biology: Mind map

Exam questions on Oxidative phosphorylation and respiratory quotient

1. Skeletal muscle cells make most of their ATP in mitochondria by oxidative phosphorylation. Electron micrographs show that the mitochondria of muscle cells have many more cristae than those of cells that are less active.
   Explain why the mitochondria in muscle cells have many cristae.2 marks
2. A volunteer who had not eaten for three days breathed through a respirometer. The volunteer used 250 cm³ of oxygen and produced 190 cm³ of carbon dioxide each minute at rest.
   Explain why the respiratory quotient for lipids is lower than that for carbohydrates.2 marks
3. A student investigates the respiration of 5 g of germinating pea seeds at 20 °C in two simple respirometers. In tube A the carbon dioxide is absorbed by potassium hydroxide solution. Tube B has no potassium hydroxide solution. The cross-sectional area of the capillary tube is 0.80 mm². In 10 minutes the coloured liquid in tube A moved 30 mm towards the seeds, and in tube B it moved 6 mm towards the seeds.
   Explain what the movement of the liquid in tube A measures and calculate the rate of this process in mm³ per minute.3 marks