Chapter 1- Biological Molecules

Question 1

What is a hydrolysis reaction

Answer 1

Reactions which lose water- used when breaking the bonds that link sub units of a polymer.

Question 2

Types of monosaccharides

Answer 2

Galactose
Glucose
Fructose

Question 3

How are two monosaccharides joined together

Answer 3

By a condensation reaction

Question 4

Steps to test reducing sugars

Answer 4

Add Benedict’s Reagent to food sample
Heat the mixture in a water bath
Orange brown colour suggests reducing sugar present

Question 5

What is the test for lipids

Answer 5

Add ethanol and shake.
Add water and shake gently.
A cloudy white precipitate indicates presence of a lipid.

Question 6

What is the test for non reducing sugars

Answer 6

Add Benedict’s reagent to food sample
Heat in water bath
Lack of Orange- brown indicates lack of reducing sugar
Add dilute hydrochloride acid
Add sodium hydrogen-carbonate and Benedict’s reagent
Orange-Brown colour indicates non-reducing sugar present.

Question 7

What is a condensation reaction

Answer 7

A reaction which produces water

Question 7

How are polysaccharides formed

Answer 7

Condensation reaction of monosaccharides

Question 8

What bonds are between disaccharides and polysaccharides

Answer 8

Glycosidic bonds

Question 10

What is the test for starch

Answer 10

Add iodine solution to food sample
Shake or stir
Blue-black computation indicates presence of starch

Question 11

What makes Starch a good for storage

Answer 11

Starch is insoluble so does not diffuse out of cells
Insoluble so doesn’t affect water potential so water is not drawn into cells by osmosis
Highly branched allows enzymes to allow alpha glucose molecules to be quickly released

Question 12

Where is starch found

Answer 12

Starch is found in plant cells

Question 13

Where is glycogen found

Answer 13

Glycogen is found in animal and bacteria cells

Question 14

What type of glucose is in starch

Answer 14

Alpha-glucose.

When hydrolysed can be easily transported and readily used in respiration.

Question 15

Name 3 characteristics of lipids

Answer 15

They contain carbon, hydrogen and carbon
They are insoluble in water
They are soluble in organic solvents such as alcohols and acetone.

Question 16

What type of glucose is in glycogen

Answer 16

Alpha glucose- Highly branched in order to allow enzymes to act on and quickly release glucose molecules.

Question 16

How does the structure of Cellulose allow cell wall turgidity.

Answer 16

Cellulose molecules are made up of Beta-glucose forming long straight unbranched chains.
The parallel chains are cross linked by hydrogen bonds adding strength.

Question 17

What are the roles of lipids

Answer 17

• Source of energy
• Waterproofing
• Insulation
• Protection

Question 19

What is the general formula for monosaccharides

Answer 19

(CH2O)n where n can be 3-7

Question 20

What bonds are formed between fatty acids and glycerol

Answer 20

Ester bonds in a condensation reaction.

Question 21

What is the difference between a saturated fatty acid and an unsaturated fatty acid.

Answer 21

Unsaturated has double carbon bonds whilst saturated has no double carbon bonds.

Question 22

How is triglycerides low mass to energy ratio related to their properties

Answer 22

Triglycerides have a low mass to energy ratio this is good for storage because a lot of energy can be stored in a small volume

Question 23

What is the effect of a non- competitive inhibitor

Answer 23

Non-competitive inhibitors attach to the enzyme changing the shape of the active site so ES complexes are unable to be formed

Question 24

How does being large and non polar relate to triglycerides properties

Answer 24

They are insoluble in water,so their storage does not affect osmosis in cells or their water potential.

Question 26

How is the phospholipid structure related to its cell recognition properties.

Answer 26

The phospholipid structure allows combining with carbohydrates forming glycolipids which is important for cell recognition

Question 27

What are the types of disaccharides

Answer 27

Glucose + Glucose > Maltose Glucose + Galactose > Lactose Glucose + Fructose > Sucrose

Question 28

How is a phospholipid different to a triglyceride

Answer 28

One of the fatty acids are replaced by a phosphate molecule.

Question 29

What are the two components of a phospholipid

Answer 29

A hydrophilic head- which interacts with water | A hydrophobic tail- which orients itself away from water.

Question 29

Explain the induced fit model

Answer 29

The enzyme is flexible and able to mound itself around the substrate. The enzyme had a general shape but this is altered in the presence of the substrate.

Question 30

How is phospholipid being polar molecules related to their properties

Answer 30

In an aqueous environment a bilayer is formed within cell surface membranes

Question 32

What is the structure of a triglyceride

Answer 32

Three fatty acids combined with glycerol.

Question 33

Explain differences between the lock and key model and the indices fit model.

Answer 33

The lock and key model proposes that the shape of the substrate exactly fits the active site of the enzyme whist the induced fit model proposes that the active site mounds around the substrate.

Question 34

Name factors which affect enzyme action.

Answer 34

pH Temperature Enzyme concentration Substrate concentration

Question 35

How does pH affect enzyme action.

Answer 35

A change in pH may cause the bonds maintaining the tertiary structure to break therefore changing the shape of the active site. Stops enzyme substrate complexes forming.

Question 36

How does temperature affect enzyme action.

Answer 36

When the temperature is increases the kinetic energy is increased so the rate of reaction increases as the number of enzyme-substrate complexes increase. When the temperature is increased past the optimum the enzyme becomes denatured and enzyme-substrate complexes are not formed. Causing the rate of reaction to increase.

Question 37

Describe the effect of increasing enzyme concentration on the rate of reaction

Answer 37

Increasing enzyme concentration increases the rate of reaction. If the number of substrate is limited the rate of reaction will plateau.

Question 38

What is the effect of substrate concentration on the rate of enzyme action.

Answer 38

If the concentration of enzyme is fixed there will only be a proportional increase. However this will plateau when all enzyme active sites are filled.

Question 38

How does a competitive inhibitor affect rate of reaction

Answer 38

A competitive inhibitor inhibits the active site as it is complementary therefore decreasing the rate of reaction ashes enzyme-substrate complexes are formed. However this is only temporary