Biological Molecules

Question 1

Reducing Sugars Test e.g Glucose

Answer 1

Add Benedictus solution to the sample
Heat it
Spectrum of colours depends on the concentration

Low conc: green
High conc: Brick red

Question 2

Non-reducing sugars e.g Sucrose

Answer 2

• Add HCL then heat the sample
• Add Sodium Hydrogen Carbonate to neutralise the the sample
• Add benedicts solution and heat it
• Spectrum of colours =Brick red is a positive result

Question 3

Emulsion Test

Answer 3

• Add the sample of Ethanol and shake it
• Add a set of volume of water
• If you get cloudy white colour, lipid is present

Question 4

DNA replication

Answer 4

1. The enzyme DNA helical breaks the hydrogen bonds between bases in the two nucleotides DNA strands. The helix unwinds to form two single strands
2. Each original strand acts as a template for a new strand. Complementary base pairing means that fee-floating DNA nucleotides are attached to their complementary exposed base on each original template strand

Question 5

DNA replication 2

Answer 5

Condensation reactions join the nucleotides of the new strand together- catalysed by the enzyme DNA POLYMERASE. Hydrogen bonds form between the bases on the original strand from the original DNA molecule and one new strand.

Question 6

Importance of monosaccharides

Answer 6

• Sources of energy (glucose)

- Able to be transported in solution in animals (as glucose in the blood)

Question 7

Monosaccharides

Answer 7

In carbohydrates the basic monomer is called a ‘saccharide’. A single monomer is called a ‘monosaccharide’

They are…

Sweet tasting
Soluble
Made of C, H and O2 atoms
General formula (CH2O)n n is between 3&7

Question 8

Cellulose

Answer 8

Cellulose differs from starch and glycogen because it it formed from Beta Glucose

Cellulose has straight, long, unbranched chains running parallel to on another, allowing H bonds to form cross-linkages between adjacent chains

Cellulose molecules group together to form microfibrils, which are arranged in parallel groups called fibres

Question 9

Disaccharides

Answer 9

Monosaccharides join together in condensation reactions to form Disaccharides. A glycosidic bond between them forms and water is formed

Question 10

Examples of Disaccharides

Answer 10

Glucose + Glucose = Maltose
Glucose + Fructose = Sucrose
Glucose + Galactose = Lactose

Question 11

Saturated Fatty Acids

Answer 11

No double carbon bond, allure carbon atoms are linked with the max number of hydrogen bonds

Question 12

Mono-unsaturated fatty acids

Answer 12

If it had one single double bond

Question 13

Polyunsaturated fatty acids

Answer 13

If it has more than one double bond

Question 14

Characteristics of Lipids

Answer 14

Contain Carbon, Hydrogen and Oxygen
The proportion of Oxygen to Carbon and Hydrogen is smaller than Carbohydrates
-INSOLUBLE in water
-SOLUBLE in organic solvents e.g acetone, alcohols

Question 15

Role of Lipids

Answer 15

Energy Source
Insulation 
Help of absorption of minerals
Waterproofing
Important in making the cell membrane 
Protection = Fat is often stored around delicate organs