5.7.9(measuring the rate of respiration)

State the name of the apparatus used to investiagte the rate of respiration

• Respirometer

Describe how a respirometer can be used to measure the rate of respiratopm

• Soda lime solution in the respirometer tube absorbs the CO2 produced by the organisms.

• This leads to a decrease in the volume of gas in the respirometer tube which leads to a decrease in pressure.

• This causes the coloured liequid in the manometer tube to rsie up towards the side with the living organisms in it

Describe how to calculate the volume of oxygen absorbed and therefore the rate of respiration

• Mark the original level of liquid

• The volume of oxygen is the difference between the volume of the original level and the volume of the coloured liquid at the end of the time period

• The rate of respiration can be calculated using by dividing the volume by the known amount of time

Describe how to reset the apparatus

• The syringe is pushed down to inject air into the system to reset the liquid in the manometer tube back to its original position

Describe how you can measure the effect of temperature on rate of respiration

• You can use a respirometer at multiple different temperatures

• In between changing each temperature, the apparatus and organisms should be allowed to acclimatise

• Then control the time for each temperature and then collect 3 readings at each temperature

What is meant by a facultative anaerobe and give an example of one

• It is an organism which can respire aerobically if oxygen is present and anaerobically if it isnt