Biological Molecules

Question 1

What monomers make up maltose?

Answer 1

Alpha glucose and alpha glucose

Question 2

What monomers make up lactose

Answer 2

Alpha glucose and galactose

Question 3

What monomers make up sucrose?

Answer 3

Alpha glucose and fructose

Question 4

What bond joins monosaccharides?

Answer 4

Glycosidic

Question 5

What is the monomer of cellulose?

Answer 5

Beta glucose

Question 6

What is the monomer of glycogen?

Answer 6

Alpha glucose

Question 7

What is the reaction that joins two molecules together?

Answer 7

Condensation reaction

Question 8

What is the reaction that breaks a chemical bond between two molecules?

Answer 8

Hydrolysis reaction and involves the use of water

Question 9

What is the monomer of a polypeptide?

Answer 9

Amino acids

Question 10

What bond is formed between two amino acids?

Answer 10

Peptide bond

Question 11

What is the monomer that makes up starch?

Answer 11

Alpha glucose

Question 12

How does cellulose structure relate to its function?

Answer 12

Long straight chains parallel chains
Linked together by many hydrogen bonds to form fibrils
Provides strength to cell wall

Question 13

What is the structure of glycogen? +why is it a good source of energy?

Answer 13

Polysaccharide of alpha glucose
Joined by glycosidic bonds
Branched structure
Hydrolysed to glucose and used in respiration

Question 14

Describe the structure of starch and how it relates to its function?

Answer 14

Insoluble - doesn’t affect water potential
Coiled (alpha helix) - so compact molecule
Large molecule - so can’t leave the cell membrane
Polymer of alpha glucose - provides glucose for respiration
Branched - more ends for faster breakdown

Question 15

What is the biochemical test for starch?

Answer 15

Iodine test
Add iodine to sample
Will turn blue/black

Question 16

Biochemical test for reducing sugar?

Answer 16

Heat with Benedict’s reagent
Will change from blue to orange/red

Question 17

Biochemical test for non-reducing sugar?

Answer 17

Heat with acid and neutralise
Heat with Benedict’s solution
Red precipitate

Question 18

Biochemical test for lipids?

Answer 18

Emulsion test
Add ethanol to sample
Then distilled water and shake for 1minute
Will turn white emulsion

Question 19

Biochemical test for proteins?

Answer 19

Biuret test

Question 20

What is the structure of a triglyceride? + bonds formed?

Answer 20

Contains 1glycerol and 3fatty acids
Forms ester bond

Question 21

What is the difference between a phospholipid and triglyceride?

Answer 21

Phospholipid contains 2 fatty acids and 1 phosphate group.
Phospholipid- condensation reaction between glycerol and fatty acid

Question 22

What is the difference between saturated fatty acid and unsaturated?

Answer 22

Saturated - single carbon carbon bonds
Unsaturated - at least one double

Question 23

What is the biochemical test for proteins?

Answer 23

Add biuret reagent
Purple colour

Question 24

Describe how the structure of a protein depends on the amino acids it contains? 5marks

Answer 24

Structure is determined by the position of Rgroup
Primary structure is a sequence of amino acids
Secondary structure is formed by hydrogen bonding
Tertiary structure is formed by bonds between Rgroups
The tertiary structure creates specific shape (active site in enzymes)
Quaternary structure contains more than 1 polypeptide

Question 25

Describe the induced fit model of enzyme action and how an enzyme acts as a catalyst

Answer 25

Enzyme lowers the activation energy needed Substrate binds to active site forming enzyme-substrate complex Active site changes shape slightly breaking bonds in the substrate

Question 26

Describe how a non-competitive inhibitor can reduce the rate of an enzyme controlled reaction

Answer 26

Attaches the the enzyme at a site other than the active site Changes the tertiary structure of the enzyme So the active site is no longer complementary to the substrate so substrate can’t bind/less enzyme-substrate complexes formed

Question 27

Describe how a competitive inhibitor reduces rate of reaction

Answer 27

Inhibitor similar shape to substrate Binds to active site Prevents enzyme-substrate complexes forming

Question 28

Describe the structure of DNA

Answer 28

Polymer of nucleotides Deoxyribose sugar, phosphate group and organic base Phosphodiester bonds between nucleotides Double helix held together by hydrogen bonds DNA bases = adenine, thymine, cytosine and guanine.

Question 29

Describe the process of semi-conservative replication

Answer 29

DNA helically breaks hydrogen bonds, unwinding alpha helix One DNA strand is used as a template Free nucleotides complementary base pair with exposed nucleotides DNA polymerase joins adjacent nucleotides Phosphodieste bond formed

Question 30

What is the difference between RNA and DNA?

Answer 30

RNA contains ribose sugar RNA contains uracil base instead of thymine

Question 31

What are the components in ATP?

Answer 31

Adenine Ribose sugar 3 phosphate groups

Question 32

What makes ATP a good source of energy

Answer 32

Universal Released in small manageable amounts

Question 33

Explain five properties that make water important for organisms. 5marks

Answer 33

Cohesion- supports columns of water in plants Large latent heat of vaporisation- provides a cooling effect through evaporation High specific heat capacity- so buffers changes in temperature Metabolite- in condensation reactions Solvent- so metabolic reactions can occur

Question 34

Describe the role of iron ions, sodium ions and phosphate ions in cells. 5marks.

Answer 34

Iron - haemoglobin associates with oxygen Sodium - contra sport of glucose into cells because sodium moved out by active transport which creates a sodium concentration gradient Phosphate ions - used in ATP + joins nucleotides in DNA