Core Practical: Investigating Respiration Flashcards
All 4 cards in this deck
What are the steps to measure the rate of respiration of small living organisms with a respirometer?
e.g. maggots in a sealed test tube- Seal the maggots in a tube with soda lime (absorbs carbon dioxide), joined to a capillary tube holding a drop of coloured liquid.
- Keep at a constant temperature and record the starting position of the drop.
- After a set time, measure how far the drop has moved towards the tube (oxygen used).
Describe a suitable control for an investigation of respiration using hydrogencarbonate indicator.
The same test tube, gauze and bung with the same indicator, but containing no living organisms (or an inert object, e.g. glass beads or dried peas).
When comparing the respiration rates of different organisms using hydrogencarbonate indicator, give three variables that must be controlled.
Same mass of organisms; same volume and concentration of indicator; same temperature (and same size of test tube).
What colour change in hydrogencarbonate indicator shows that more carbon dioxide is present?
Red to yellow.