2.4 Flashcards Preview

Biology - 2 > 2.4 > Flashcards

Flashcards in 2.4 Deck (14):
1

What techniques can be used to detect/measure glucose levels?

Benedict's reagent
Biosensors
Colorimeters

2

What can be used to test for the presence of a reducing sugar?

Benedict's reagent

3

Describe the Benedict's test

1) Add reagent to the solution (equal volumes)
2) Heat in a boiling water bath
3) Observe the colour of the precipitate formed

4

What colour will the precipitate be if a reducing sugar is present?

Brick red

5

What is a test for a non-reducing sugar?

1) Add HCl to the sugar that has tested negative in Benedict's test
2) Add HCO3- solution
3) Test with pH paper to check neutral
4) Re-test solution in water bath with Benedict's reagent
5) If a non-reducing sugar is present, it turns brick red

6

How do biosensors work?

Changes colour if a substance binds to it

7

What are examples of biosensors?

Clinistrips
Glucometers

8

What enzyme do clinistrips contain?

Glucose oxidase

9

How do clinistrips work?

Glucose in urine is oxidised to gluconic acid + H2O2
Enzyme breaks down H2O2
Oxygen oxidises a colour dye on test pad

10

What enzyme do glucometers contain?

Glucose dehydrogenase

11

How do glucometers work?

Enzyme converts blood glucose into gluconolactone
Small current is produced
Current is detected by an electrode on test strip
Current is read by a meter

12

What is a colorimeter?

A device that shines a beam of light through a solution and measures the absorbance of particular wavelengths in light

13

What reagent can be used to detect starch?

Iodine-KI reagent

14

What colour is produced if starch is present?

Blue-black colour