Investigating effect of different substrates on yeast respiration

Carried out experiment in school using fructose, glucose, galactose, sucrose and lactose... didn't really get very good results.
Measured the volume of CO2 produced by respiring yeast in solutions of each of these
Can anyone explain what patterns/ trends I should have got?

(edited 14 years ago)

Reply 1

Eloades11

My best guess is that the smaller the sugar, the more respiration that takes place therefore the more CO2 produced? Glucose is needed for respiration, so the plant would have to break down the over molecules first in order to use them for respiration.

Reply 2

LuhLah

OMG I DID THIS lol

Basically, as the carbon no. in the sugars increased, the quantity of CO2 given off per sugar should have decreased. This is because the sugars need to be broken down into a hexose (6-carbon sugar) before they can undergo respiration.

Reply 3

Eloades11

LuhLah

Did you get these results? This is what I think should have happened, we are doing respiration in A2 Biology this week, and the starting sugar is glucose(C6H12O6?) And because you have to break down the bigger molecules first, this uses more time so slower respiration.
All of this is assuming that the more glucose you use is proportional to the amount of CO2 produced.