respirometer Flashcards
what is a respirometer used for
-used to measure and investigate the rate of oxygen consumption during aerobic respiration
what are the different parts of a respirometer and their use
syringe= to reset manometer fluid to zero
airtight bung
-two test tubes : one as control one experimental with seeds or invertebrates
-soda lime pellets in each test tube to absorb CO2
-U-tube manometer and scale to measure rate of o2 uptake = fluid moves towards respiring material as o2 is used up
-temp controlled water bath
why does the manometer fluid move
-moves towards respiring material due to the decrease of pressure inside the tube when oxygen is used up
why is a thermobarometer used
-it is essential to eliminate volume changes that could be caused by anything other than exchange of carbon dioxide and oxygen
-small changes in temperature or pressure cause air in this vessel to expand or contract, compensating for similar changes in the first vessel
describe the method of carrying out the respirometer practical
Measure oxygen consumption: set up the respirometer and run the experiment with both tubes in a controlled temperature water bath. Use the manometer reading to calculate the change in gas volume within a given time, x cm3 min-1
Reset the apparatus: Allow air to reenter the tubes via the screw cap and reset the manometer fluid using the syringe. Change the temperature of the water bath and allow the tubes to acclimate, then close the screw clip to begin the experiment
Run the experiment again: use the manometer reading to calculate the change in gas volume in a given time, y cm3 min-1
Repeat experiment several times at different temperatures
how do you calculate the volume of o2 uptake using a respirometer
-measure distance liquid has moved in a fixed time period
-known diameter of capillary tube
- use πr2h where h is the distance traveled by liquid
-if time interval was e.g 10 mins divide answer by 10 for distance per min etc
