tests for food

Question 1

How to prepare food sample

Answer 1

Break food up using mortar and pestle

Put into beaker with distilled water

Stir with glass rod until some dissolve

Filter some with the funnel to get rid of solid bits of food

Question 2

What types of Sugars are there?

Answer 2

Non reducing and Reducing

Question 3

What type of Sugar does Benedicts test test for?

Answer 3

Reucing sugars

Question 4

Benedicts test?

Answer 4

Transfer 5cm3 of food sample to test tube

Prepare water bath at 75C’

Add 10 drops of benedicts solution to test tube and place in water bath for 5 minutres

Use test tube to put in water bath

Blue –> Green Yellow or Brick red depending on Concentration

Question 5

Test for Starch?

Answer 5

Iodine Test

5cm3 of food sample and add few drops of Iodine Solution

Shake gently

Browny Orange colour –> Blue Black

Question 6

Test for Proteins?

Answer 6

Biuret Test

2CM3 OF SAMPLE TO TEST TUBE
2CM3 OF BIURET SOLUTION (POTASSIUM HYDROXIDE AND COPPER SULFATE) TO SAMPLE
TURNS IT BLUE
GENTLY SHAKE

BLUE–>PINK OR PURPLE

Question 7

Test for Lipids?

Answer 7

Add FOOD SAMPLE TO TEST TUBE
Add 2cm3 of Ethanol
Shake Vigorously
Add 2cm3 of water

Cloudy White colour

Question 8

What are examples of Polysacharrides?

Answer 8

Starch Cellulose and Glycogen

Question 9

What two things are triglecyrides made from?

Answer 9

Glycerol and Three Fatty Acids

Question 10

What are the problems with increasing temperature to speed up the rate of reaction?

Answer 10

requires a lot of energy
can damage cells
speeds up non-useful reaction

Question 11

Definition of a Catalyst?

Answer 11

A substance which increases the rat of reaction by using an alternative pathway without being changed or used up

Question 12

Enzymes?

Answer 12

Biological Catalysts