Biological Molecules

Question 1

Name the elements present in a carbohydrate

Answer 1

Carbon, C
Oxygen, O
Hydrogen, H

Question 2

Name the elements present in a lipid

Answer 2

Carbon, C
Hydrogen, H
Oxygen, O

Question 3

Name the elements present in a protein

Answer 3

Carbon, C
Hydrogen, H
Oxygen, O
Nitrogen, N

Question 4

What are the basic units of carbohydrates?

Answer 4

Simple sugars (monosaccharides) such as glucose and fructose.

Question 5

Name 2 monosaccharides

Answer 5

Glucose

Fructose

Question 6

Give 2 examples of lipids

Answer 6

Fats and oils

Question 7

Define a lipid

Answer 7

A large molecule made from smaller units of fatty acids and glycerol

Question 8

Define a protein

Answer 8

A large molecule made from smaller units of amino acids.

Question 9

Describe the test for glucose

Answer 9

• Benedict’s reagent
• blue -> brick red
• heat after adding reagent

Question 10

Describe the test for starch

Answer 10

• iodine test

- orange/ brown -> blue/black

Question 11

Describe the test for lipids

Answer 11

• emulsion test
• add ethanol to solution and then add it a test tube of water
• turns into milky emulsion

Question 12

Describe test for proteins

Answer 12

• Biuret reagent

- blue -> lilac / purple

Question 13

Define an enzyme

Answer 13

A protein that functions as a biological catalyst- a substance that speeds up a chemical reaction without being changed by the reaction.

Question 14

Describe how an enzyme works.

Answer 14

1. Substrate collides with active site of enzyme and becomes attached, forming an enzyme substrate complex.
2. Enzyme catalyses the breakdown of the substrate
3. Products are released from the active site

Question 15

Describe the effect of increasing temperature on the rate of enzyme activity.

Answer 15

• an increase in temp will initially increase rate of activity
• enzymes and substrates have more kinetic energy and therefore collide more often, forming more complexes
• if temp exceeds optimum, active site loses shape and enzyme becomes denatured
• no more complexes formed, so rate decreases.

Question 16

Describe the effect of increasing pH on the rate of enzyme activity.

Answer 16

All enzymes have an optimum pH at which they work best. Either side of this pH, the active site loses its shape and the enzyme becomes denatured, meaning rate of activity will decrease.