Biological molecules

Question 1

Monomers

Answer 1

Small, repeating units which form larger molecules

Question 2

Polymers

Answer 2

Long molecules, consisting of chains of small monomer molecules

Question 3

Condensation reaction

Answer 3

A polymerisation reaction between two monomers which eliminates a water molecule

Question 4

Hydrolysis reaction

Answer 4

A reaction that breaks a chemical bond between monomers, using a water molecule

Question 5

Monosaccharide

Answer 5

A single sugar monomer, from which larger carbohydrates can be formed

Question 6

How is a glycosidic bond formed?

Answer 6

A condensation reaction between two monosaccharides

Question 7

List the 3 main examples of polysaccharides

Answer 7

• starch
• glycogen
• cellulose

Question 8

Describe Benedict’s test for reducing sugars

Answer 8

Heat a solution of the sample with Benedict’s reagent to over 60C for 5 minutes
Solution turns orange/brick-red if reducing sugars are present

Question 9

Name the 2 main lipid groups

Answer 9

Phospholipids (fats)
Triglycerides (oils)

Question 10

Give 4 roles of lipids

Answer 10

• storing energy
• thermal insulation
• waterproofing
• protection

Question 11

What bond is formed by the condensation reaction between glycerol and a fatty acid?

Answer 11

Ester bond

Question 12

Describe the emulsion test for lipids

Answer 12

• mix the sample with ethanol in a clear test tube
• shake, add water, then shake again
• a cloudy white colour (precipitate) indicates that lipids are present

Question 13

What monomers make up proteins?

Answer 13

Amino acids

Question 14

Peptide bond

Answer 14

Bond between two amino acids

Question 15

Polypeptide

Answer 15

Chain of amino acids bonded together

Question 16

Describe biuret test for proteins

Answer 16

• Mix with NaOH solution (room temperature)
• add dilute copper (II) sulphate solution and mix gently
• purple colour for positive result

Question 17

How does an enzyme affect a reaction?

Answer 17

Lowers activation energy, therefore increasing rate

Question 18

List factors affecting enzyme action

Answer 18

• temperature
• pH of solution
• concentration of enzyme / substrate
• concentration of inhibitors

Question 19

Competitive inhibitor

Answer 19

A molecule which occupies the active site of the enzyme, as it shares a similar shape to the substrate

Question 20

Non-competitive inhibitor

Answer 20

A molecule that changes the active site, by binding to another part of the enzyme

Question 20

Peptide bond

Answer 20

Bond between two amino acids