pag respirometer Flashcards
what does respirometer measure
rate of oxygen consumption in aerobic respiration
what is the purpose of the soda lime
to absorb CO2 produced so volume of O2 absorbed can be measured
why does the apparatus need to be airtight
prevent air entering or leaving as this would affect volume and therefore pressure, which would affect movement of coloured liquid
which way does the liquid move and why
- towards experimental tube containing organism
- organism takes in oxygen for respiration
- volume decreases in test tube so pressure decreases in test tube
- pressure in control tube/syringe is comparatively higher
- liquid moves towards experimental tube
units for respiration rate
volume per time
eg cm3 min-1
what is in the control test tube
glass beads of same mass as organism in other test tube
limitations
- oxygen uptake may not be a good representation of respiration rate
- oxygen could leak
- difficult to read meniscus
control variables
- mass of organisms
- temperature (use water bath/thermometer)
- mass of soda lime
- syringe size if used
describe how you would add the red fluid to the capillary tube at the start of the experiment
capillary tube dipped into a small beaker of red fluid and allowed to
run
what info is needed to compare oxygen uptake between organisms
mass used
how would the experiment differ using a seed and a small animal
- ethical use of animal eg screen so it cannot touch soda lime
- bigger syringe needed for animal
what is measured and why
- distance moved by fluid in capillary tube
- gives rate of oxygen uptake
- to estimate rate of aerobic respiration