Biological Molecules B3

Question 1

Carbohydrates

Answer 1

Molecules made up of Carbon, Hydrogen and Oxygen

Starch and glycogen are made from many glucose molecules joined together.

Question 2

Protein

Answer 2

Molecules made up of Carbon, Hydrogen, Oxygen and Nitrogen

Proteins are polymers (large molecules) that are made from many Amino Acids (smaller molecules) joined together.

Question 3

Fats

Answer 3

Molecules made up of Carbon, Hydrogen and Oxygen

Fats and oils are made from fatty acids and glycerol molecules (1 glycerol joined to 3 fatty acids)- Fatty acid chain

Question 4

Starch Test- Iodine

Answer 4

Iodine (Orangey-brown) turns blue-black when it reacts with starch

Drop iodine onto food sample directly or small pieces on a spotting tile

Question 5

Glucose Test- Benedicts

Answer 5

Benedict’s solution (blue) turns orangey-brick red when it is heated with glucose

1. ) Add a sample of the food to a boiling tube and add Benedict’s solution.
2. ) Heat this with a Bunsen

3.) Changes colour depending on the amount of glucose (Blue to green to orange to brick red)

Question 6

Protein Test- Biuret

Answer 6

Solution turns purple is protein is present.

1. ) Add a few drops of potassium hydroxide and shake
2. ) Add a few drops of copper sulphate and observe.

Question 7

Fat test - Ethanol Emulsion

Answer 7

Fats go cloudy white when they are mixed with ethanol and water.

1. ) Grind down food with ethanol
2. ) Filter it into a test tube
3. ) Add water and observe

Question 8

Water as a Solvent

Answer 8

Water is the universal solvent and dissolves substances allowing them to diffuse through it.

Our bodies are 65% water so it is very important

This allows transportation of substances around the body ready to diffuse in and out of different locations.