Required Practical 9

Question 1

Describe how a respirometer can be used to measure rate of aerobic respiration

Answer 1

• add set mass of yeast to set volume of substrate
• add buffer to keep pH constant
• add set volume of chemical that absorbs CO2
• place in water bath to allow to equilibrate
• measure distance moved by coloured liquid in set time

Question 2

Describe how a respirometer can be used to measure rate of anaerobic respiration

Answer 2

• same but no chemical that absorbs CO2
• make sure conditions are anaerobic (eg. Layer of oil, chemical that absorbs O2)

Question 3

Describe how rate of respiration can be calculated

Answer 3

• calculate volume of O2 consumed / CO2 released (cross sectional area of capillary tube x distance liquid moved)
• divide by mass of organism and time taken