Core Prac 16

Question 1

State the role of soda lime in this experiment, explain why it is needed

Answer 1

Soda lime absorbs the CO2 being produced, so the difference in oxygen concentration is observed as a difference in pressure

Question 2

State the role of the syringe in this experiment, explain why it is needed

Answer 2

Allows for movement of liquid to be seen due to changes in pressure in a closed system

Question 3

Devise a valid and reliable method for investigating then rate of respiration at different temperatures

Answer 3

IV: temperature (at least 5 diff)
DV: rate of respiration, mm3/s
CV: type/number of mung beans, time spent respiring (3 mins)
Using a u shaped respirometer, set up live mung beans in one test tube and glass beads of the same weight, connected by the respirometer
Place the test tubes in a hot water bath and set to desired temp, allowing for acclimatisation (at least 5 diff temps)
Close valves and weight for 3 mins, at end measure how far liquid in u-tube has moved in mm
Repeat for more reliable results

Question 4

Describe how you would calculate the rate of respiration of organism in a given time period

Answer 4

Distance liquid moved (mm) / time took to move (s)