Topic 7: Run For Your Life

Question 1

Answer 1

• decrease in {pressure/volume} (in the tube) (1)
• as oxygen {used / taken out of tube / taken up
  by maggots} (1)
• as carbon dioxide released is absorbed by
  potassium hydroxide (1

Question 2

(c) Devise an investigation, using a respirometer, to find the optimum temperature
for respiration in maggots.
(5

Answer 2

• suitable range of temperatures (1)
• control of a relevant biotic variable (1)
• record distance bubble travels in a set
  time / record time taken to travel a set
  distance (1)
• judgement of optimum (1)
• details of respirometer set up (1)
• repeats at each temperature to calculate
  a mean value (1)
  e.g. 5- 50° C Range to be at least 3 temperatures.
  e.g. age, species, mass or size of maggots
  IGNORE number of maggots
  e.g. note first temperature where distance bubble
  moves is less, so previous highest temperature to
  this is the optimum
  ALLOW temperature at which rate is highest
  e.g. use water baths, soda lime, time for
  organisms to acclimatise
  ALLOW average for mean

Question 3

Answer 3

• predominance of {type I / slow twitch} muscle fibres (1)
• (long duration activity so) require muscle fibres that are slow to
  fatigue (1)
• low level of anaerobic respiration reduces lactic acid build up (1)
• {ATP needed over a longer time frame / (overall) more ATP
  needed} so provided by (more efficient process) {aerobic
  respiration / oxidative phosphorylation / chemiosmosis} (1)
• high mitochondria concentration for (more) aerobic respiration
  (1)
• {type II / fast twitch} muscle fibre allows runner to run faster
  (towards the end) (1