Anaerobic respirationEdexcel A-Level Biology B: Mind map

Exam questions on Anaerobic respiration

1. A 400 m sprinter runs a race lasting about 50 seconds. Oxygen cannot be delivered to her leg muscles quickly enough to meet demand, so much of the ATP for the final stretch is made without oxygen.
   Explain why the conversion of pyruvate to lactate allows glycolysis to continue in her muscles.2 marks
2. Rice plants grown in flooded paddy fields have roots surrounded by waterlogged soil that contains very little oxygen. Root cells of these plants can keep respiring for a time without oxygen.
   State two differences between anaerobic respiration in these root cells and in mammalian muscle cells.2 marks
3. A student used a respirometer to measure the rate of oxygen uptake by 5 g of germinating pea seeds at 20 °C. Carbon dioxide produced was absorbed by potassium hydroxide solution. A coloured liquid droplet in a capillary tube of internal radius 0.50 mm moved 24 mm towards the seeds in 6.0 minutes. A second, control tube contained glass beads with the same volume as the peas.
   Calculate the rate of oxygen uptake of the seeds in mm³ min⁻¹. Give your answer to three significant figures and show your working.3 marks