required practical 9 Flashcards
investigation into the effect of a named variable on the rate of respiration of cultures of single-celled organisms
1
Q
what is the purpose of methylene blue?
A
it is a redox dye that acts as an alternate electron acceptor of the electrons transferred during ATP synthesis, it turns from blue to colourless to indicate the end point
2
Q
method
A
- set up water bath at 35c
- add 5cm3 of yeast and glucose to three test tubes and add them to the water bath for 10 minutes
- add 2cm3 of methylene blue and start the timer, shake for 10 seconds and place back in water bath
- record how long it takes solution to go from blue to colourless
- repeat using different temperatures
- find the mean for each temperature
3
Q
what is the equation for rate of respiration?
A
1/mean time
4
Q
why does the yeast solution need to be buffered?
A
to maintain a constant pH so the enzymes are functioning at the optimum
5
Q
what is the effect of temperature on respiration?
A
as temp increases, ROR increases because enzyme activity increases
beyond optimum, enzyme activity decreases beacuse they denature