Biological Molecules

Question 1

 What are monomers?

Answer 1

Smaller units from which larger molecules are made

Question 2

What are polymers?

Answer 2

Molecules made from a large number of monomers joined together

Question 3

What is a condensation reaction?

Answer 3

A reaction that joins two molecules together to form a chemical bond whilst eliminating a molecule of water

Question 4

What is a hydrolysis reaction?

Answer 4

A reaction that breaks a chemical bond between two molecules and involves the use of a water molecule

Question 5

What is a monosaccharide?

Answer 5

Monomers from which larger carbohydrates are made

Question 6

How is a glycosidic bond formed?

Answer 6

A condensation reaction between two monosaccharides

Question 7

Name the three main examples of polysaccharides

Answer 7

Glycogen, starch, cellulose

Question 8

Describe Benedict’s test for reducing sugars

Answer 8

Gently heat a solution of a food sample with an equal volume of Benedict’s solution for five minutes, the solution turns orange/brown if reducing sugar is present

Question 9

Name the two main groups of lipids

Answer 9

Phospholipids, triglycerides (fats and oils)

Question 10

Give four roles of lipids 

Answer 10

Source of energy, waterproofing, insulation, protection

Question 11

What is an ester bond?

Answer 11

A bond formed by a condensation reaction between glycerol and a fatty acid

Question 12

Describe the emulsion test for lipids

Answer 12

Mix the sample with ethanol in a clean test tube, shake the sample, add water, shake the sample again,a cloudy white colour indicates that lipids are present

Question 13

What are the monomers that make up proteins?

Answer 13

Amino acids

Question 14

Draw the structure of an amino acid

Answer 14

R
|
|
H2N — C — COOH
|
|
H

Question 15

How is a peptide bond formed?

Answer 15

A condensation reaction between two amino acids

Question 16

What is a polypeptide?

Answer 16

Many amino acids joined together

Question 17

Describe the biuret test for proteins

Answer 17

Mix the sample with sodium hydroxide solution at room temperature, add very dilute copper(II) sulphate solution, mix gently, a purple colour indicates that peptide bonds are present

Question 18

How does an enzyme affect a reaction?

Answer 18

It lowers the activation energy

Question 19

Give five factors which can affect enzyme action

Answer 19

Temperature, pH, enzyme concentration, substrate concentration, inhibitor concentration

Question 20

What is a competitive inhibitor?

Answer 20

A molecule with a similar shape to the substrate, allowing it to occupy the active site of the enzyme

Question 21

What is a non-competitive inhibitor?

Answer 21

A molecule that changes the shape of the enzyme by binding somewhere other than the active site