Practicals

Question 1

Explain how to perform a serial dilution of a glucose solution

Answer 1

take 5 test tubes
and 10cm3 solution to the first test tube
add 5cm3 distilled water to the other four
use a pipette to put 5cm3 solution into the second test tube
mix well
repeat for other test tubes

Question 2

Describe how to create a calibration curve using a serial dilution

Answer 2

add benedicts solution to each test tube including control
put in water bath at 80*c for five minutes
leave for 24 hours to remove precipitate
use a colorimeter with red filter to measure the absorbance in each tube
plot a calibration curve

Question 3

Describe how to measure oxygen produced from the breakdown of hydrogen peroxide

Answer 3

set up boiling tubes containing the same volume and concentration of h2o2
add equal volumes of buffer solution to each tube (to control pH)
use a delivery tube and upside down measuring cylinder
add boiling tubes to water baths along with catalase in seperate tubes
add same volume of catalase to each tube
record how much oxygen is produced in the first 60 seconds

Question 4

Describe how to find the water potential of a potato

Answer 4

perform a serial dilution of sucrose solutions
use cork borer to make potato the same size
weight each potato and place in each solution
leave potatoes for 30 mins
remove potstoes and pat dry
weigh each potato again and calculate %change in mass
0% change in mass shows the water potential of the potato tissue