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Question 1

what is the Benedict’s test

Answer 1

its a test for sugars

1.Place two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid. Add about 1 cm3 depth of water to the tube and stir to mix.
2.Add an equal volume of Benedict’s solution and mix.
3.Place the tube in a water bath at about 95°C for a few minutes.
4.Record the colour of the solution.

Benedict’s solution gradually turns from blue to cloudy orange or brick red when heated with a reducing sugar.

Question 2

what is the iodine test

Answer 2

test for starch

1.Place one spatula of the food sample on a dish or 1 cm3 if the sample is liquid.
2.Using a dropper, place a few drops of iodine solution onto the food.
3.Record any change in the colour of the solution.

Starch is detected using
iodine solution This turns blue-black in the presence of starch.

Question 3

what is the biuret test

Answer 3

Biuret test for proteins

1.Place one-two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid. Add about 1 cm3 depth of water to the tube and stir to mix.
2.Add an equal volume of potassium hydroxide solution to the tube and stir.
3.Add two drops of copper sulfate solution and stir for two minutes.
4.Record the colour of the solution.

Proteins are detected using
Biuret reagent This turns a mauve or purple colour when mixed with protein.

Question 4

What is the ethanol emulsion test?

Answer 4

Emulsion test for lipids
1.Place two spatulas of the food sample into a test tube or 1 cm3 if the sample is liquid.
2.Add 2 cm3 of ethanol to the tube. Cover the end of the tube and shake the tube vigorously.
3.Allow the contents to settle.
4.Pour the liquid from the top of the mixture into a test tube half-filled with water.
5.Record the level of the food and whether the water is cloudy or clear.

turns milky

Question 5

What is the retina

Answer 5

Contains light receptors there are two types of light receptors called rods and cones. Rods are more sensitive to light so they help you see in dim light and cones produce colour vision.

Question 6

What is the pupil reflex

Answer 6

The amount of light entering they eye is controlled by a reflex action. The size of the pupil changes in response to bright light or dim light. This is controlled by the muscles of the iris