required practical 11: production of a dilution series of a glucose solution

Question 1

how is a calibration curve produced for the solution

Answer 1

use distilled water and a glucose solution of a known concentration to produce the dilution series
heat a set volume of each solution with a set volume of Benedict’s reagent.
measure absorbance of each solution using a colorimeter
plot graph - absorbance on the x axis and conc of glucose on the y axis

Question 2

how is the concentration of glucose in an unknown urine sample identified using a calibration curve

Answer 2

perform benedicts test on sample, using the same volumes as the calibration curve
measure absorbance using a colorimeter
read off absorbance value to find associated glucose concentration

Question 3

what variables are controlled

Answer 3

volume of sample
volume of benedicts solution
temperature of water bath
the time samples spend in the water bath

Question 4

why does a high glucose concentration cause glucose to be present in the urine of a diabetic person

Answer 4

not all the glucose is absorbed at the proximal convoluted tubule as the glucose transport proteins are saturated