module 2 - 3.4 biochemical testing

Question 1

what is the test for reducing sugars?

Answer 1

benedict’s test

Question 2

what is the procedure carried out when testing for reducing sugars?

Answer 2

• place sample to be tested on in boiling tube
• make sure its in liquid form (grind up or blend in water)
• add equal volume of benedict’s reagent
• heat mixture gently in boiling water bath for 5 mins

Question 3

what colour will the solution go if there is no reducing sugar present?

Answer 3

blue

Question 4

what colour will the solution go if there is very low reducing sugar present?

Answer 4

green

Question 5

what colour will the solution go if there is low reducing sugar present?

Answer 5

yellow

Question 6

what colour will the solution go if there is a medium amount reducing sugar present?

Answer 6

orange

Question 7

what colour will the solution go if there is high reducing sugar present?

Answer 7

brick-red

Question 8

what are some examples of reducing sugars?

Answer 8

galactose, glucose, fructose, maltose

Question 9

what is an example of a non-reducing sugar?

Answer 9

sucrose

Question 10

how do we know if non-reducing sugars are present?

Answer 10

they do not react with benedict’s solution (solution remains blue)

Question 11

what is the test for starch?

Answer 11

iodine

Question 12

what is the colour change if starch is present?

Answer 12

from brown/ yellow to blue/ black

Question 13

what happens if there is no starch present?

Answer 13

solution remains yellow/ brown

Question 14

what is the test for fats/ lipids?

Answer 14

emulsion test (using ethanol)

Question 15

what is the procedure for testing for fats?

Answer 15

• add ethanol to substance and shake vigorously
• pour solution into test tube containing water

Question 16

what is the test for proteins?

Answer 16

biuret test