Biological Molicules And Food Tests

Question 1

What are biological molecules

Answer 1

Carbohydrates, lipids and proteins. They are long complex molecules made up from smaller basic units.

Question 2

What are carbohydrates made up of

Answer 2

Simple sugars

Question 3

What elements do carbohydrates contain

Answer 3

Carbon, hydrogen, oxygen

Question 4

What are proteins made up of

Answer 4

Amino acids

Question 5

What elements do proteins contain

Answer 5

Carbon, nitrogen, hydrogen and oxygen

Question 6

What are lipids made up of

Answer 6

Three fatty acids and glycerol

Question 7

What elements do lipids contain

Answer 7

Carbon, hydrogen, oxygen

Question 8

How do you prepare a food sample

Answer 8

Get food and break it up with pestle and mortar
Transfer food to beaker and add water
Stir mixture with glass rod to dissolve some food
Filter solution using funnel lined with filter paper to get rid of solid food

Question 9

Which food test tests for glucose

Answer 9

Benedicts

Question 10

Which food test tests for starch

Answer 10

Iodine solution

Question 11

Which food test tests for protein

Answer 11

Biuret

Question 12

Which food test tests for lipids

Answer 12

Sudan III

Question 13

What food contains glucose

Answer 13

Biscuits, cereal, bread,

Question 14

What food contains starch

Answer 14

Pasta, Rice, potatoes

Question 15

What food contains protein

Answer 15

Meat, cheese

Question 16

What food contains lipids

Answer 16

Olive oil, margarine, milk

Question 17

What is benedicts solutions normal colour

Answer 17

Blue

Question 18

How to test for glucose with benedicts solution

Answer 18

Prepare food sample
Transfer 5cm cubed to a test tube
Prepare water bath to 75 celcius
Add benedicts solution to test tube (10 drops) with pipette
Put test tube in water bath using a test tube holder and leave for 5 minuets and make sure the tube is facing away from you

If the food sample contains glucose the solution will change to green or yellow in low concentrations and brick red in high concentrations.

Question 19

What colour does benedicts solution change to if glucose is present

Answer 19

Green or yellow in low concentrations and brick red in high consentrations

Question 20

How to test for starch with iodine

Answer 20

Make food sample and transfer 5cm cubed to test tube
Add a few drops of iodine and gently shake to mix
If sample contains starch the solution will cha he to black or blue black

Question 21

What is iodine solutions normal colour

Answer 21

Brown orange

Question 22

If starch is present what colour will iodine solution change to

Answer 22

Black or blue black

Question 23

What is biuret solution normal color

Answer 23

Blue

Question 24

How to test for protein with biuret solution

Answer 24

Prepare food sample and transfer 2cm cube to test tube
Add 2cm cube if biuret solution to sample and gently shake to mix
If the sample contains protein the solution will change to pink or purple

Question 25

What colour will biuret solution change to if protein is present

Answer 25

If the sample contains protein the solution will change to pink or purple

Question 26

How to test for lipids with Sudan III stay solution

Answer 26

Prepare food sample ad transfer 5cm cubed to test tube (no need to filter solid food)
Add 3 drops of Sudan III with pipette and shake gently to mix
If the sample contains lipids the mixture will separate into two layers and the top layer will be bright red

Question 27

What colour will Sudan III stain solution turn if lipids are present

Answer 27

If the sample contains lipids the mixture will separate into two layers and the top layer will be bright red

Question 28

What is the chemical formula for glucose

Answer 28

C6 H12 O6

Question 29

How do you experiment to see how well enzymes work at different temps

Answer 29

Potatoes contain enzyme catalase which breaks down hydrogen peroxide.

1. Place a 1cm cube if potato in 2 test tubes
2. Cover with water
3. Keep first tube at room temp and place second in a water bath
4. Ad 5ml of hydrogen peroxide to both tubes and record the amount of bubbling in each tube

There should be more bubbling in room temp as room temp is closer to body temp.