important

Question 1

Respirometers why would the coloured liquid move towards the left

Answer 1

as the right has an increased vol and pressure however the left absorbs o2 and co2 therefore has a lower vol and co2 due to it respiring aerobically to measure the o2 production and the coloured liquid then moves towards the left

Question 2

why would it move towards the right away from the experimental

Answer 2

absorbing the oxygen on the left whilst producing co2 due to anaerobic respiraiton and therefore this increases the pressure and vol of the left so it moves towards the right where there is a lower pressure this time.

Question 3

why the apparatus was left for 10 mins, 3 points

Answer 3

to allow it to reach equilibrium
to allow for expansion for pressure changes
to allow the respiration rates of the seefds to stabilise

Question 4

why was it set to 20 degrees

Answer 4

optimum temp for normal growth of seeds

optimum temp for enzymes involved in resp

Question 5

practical 9

Answer 5

yeast and glucose mixed together along with a redox indicator. this is to see the rate of resp due to chances in temp.

the methylene blue or the ttc gains protons or electrons, dehydrogenase enzymes that occur in the yeast removes H from nadh and then the redox indicators pick them reducing them= colour change

Question 6

what do you do before the experiment

Answer 6

first allow the test tubes to equilibrate so that their all at the same temps before you start the experiment.

they are subjective, ttc forms a red ppt and the yeast is cream so it would form pink, methylene blue goes from blue to colourless. this end point subjective.

Question 7

why glucose added

Answer 7

as it is the respiratory substrate.

dehydrogenase removes during glycolysis, link krebs and even oxidative phosphorylation

repeat exp at different temps.
rate= 1/mean time

Question 8

why do we not shake the test tubes when adding the things

Answer 8

as shaking introduces oxygen, oxygen is a terminal electron acceptor however in this reac we want the redox indicator to accept the electrons and get reduced= colour change= rate of resp

eventually reac stops as glucose no logner limiting factor used up or ethanol conc high kills cells

Question 9

why optimum rate fealls

Answer 9

bc of that or due to an increase in enzymes = denaturation. when temp deviates from optimum rate decreases bc electron
accepting slows as dehydrogenase slows so less protons from the co enzymes in the first place so less for the redox indicator