Core Practical: Investigating Respiration Flashcards
All 6 cards in this deck
What are the steps to investigate the rate of respiration using hydrogencarbonate indicator?
e.g. comparing germinating peas with dried peas- Put equal masses of organisms on gauze above the same volume of indicator in sealed tubes: germinating peas, dried peas.
- Leave for a set time at the same temperature.
- Record the colour: red → yellow shows carbon dioxide released, so the germinating peas are respiring.
How is the rate of respiration worked out from a respirometer?
rate of respiration = distance moved by the coloured drop ÷ time taken (e.g. mm per minute)
What happens to the rate of respiration measured in a respirometer as the temperature is increased (up to about 40 °C)?
It increases — the enzyme-controlled reactions happen faster, so oxygen is used up more quickly.
In a respirometer or indicator investigation into respiration, what should the control contain?
The same apparatus set up with no living organisms — e.g. an equal mass of glass beads instead of the organisms.
What piece of equipment should be used to keep all tubes at the same temperature in a respiration investigation?
A water bath, so temperature is kept the same and results are comparable.
In a respirometer, what is the soda lime for?
It absorbs the carbon dioxide the organisms give out, so any change in gas volume is caused only by the oxygen they take in.