Exam Questions

Question 1

Name the covalent bond between 2 adjacent amino acids in a chain of amino acids

Answer 1

-peptide

Question 2

Name the type of reaction involved in breaking peptide bonds

Answer 2

-hydrolysis
-adding water to break the H bonds

Question 3

Describe how an enzyme breaks down

Answer 3

-substrate is complementary to active site
-substrate fits onto active site
-induced fit
-forms enzyme substrate complex
-destabilises bonds
-amino acids leave active site

Question 4

Describe how to do the emulsion test for lipids and how a positive result would be identified

Answer 4

-add ethanol
-goes cloudy

Question 5

How might lipid content of mycoprotein differ from food that comes from animals?

Answer 5

-less lipid
-less fat
-more unsaturated

Question 6

Describe the formation of H bonds between 2 molecules of water and explain why water can form these bonds

Answer 6

-hydrogen binds to oxygen molecules
-electropositive
-polar molecule

Question 7

Why is the ability of water to act as a solvent important for the survival of organisms?

Answer 7

-medium for reactions
-allows ionic compounds to separate
-transport in xylem + phloem

Question 8

Describe the structure of collagen molecule

Answer 8

-peptide bonds
-helix
-3 polypeptide chains
-H bonds between chains
-no hydrophilic groups on outside
-cross links
-fibril

Question 9

What bond joins monosaccharides together?

Answer 9

glycosidic

Question 10

How is cellulose formed?

Answer 10

-condensation polymerisation of beta glucose

Question 11

What role does hydrogen play in helping cut flowers last longer?

Answer 11

-to regulate pH

Question 12

What role does sodium play in helping cut flowers last longer?

Answer 12

-to regulate water potential

Question 13

Explain how properties relating to the density of water contribute to the survival of organisms

Answer 13

-ice is less dense than water = floats
-animals can float
-ice provides a habitat for some species
-ice insulates water below

Question 14

Outline the properties of water which make it an ideal habitat for an amphibian

Answer 14

-high specific heat capacity
-high density = buoyancy

Question 15

Explain how the structure of phospholipids allow them to form the bilayer of a plasma membrane

Answer 15

-hydrophilic head = attracts water forming H bonds
-hydrophobic head = forms bilayer as they repel water
-polar molecule

Question 16

Describe and explain how the structure and properties of different carbs and lipid molecules suit them to their role as energy storage molecules in plants and animals

Answer 16

carbs
-polymers of glucose - used to release energy
-1-4 glycosidic bonds = easy to make + break = glucose
-coiled shape = take up less space
-unbranched amylose = no need for rapid release of monomers in plants
-glycogen more branched = more rapid release in animals
-fats insoluble - don’t affect WP

Question 17

Name 3 functions of triglycerides in living organisms

Answer 17

1. energy storage
2. thermal insulation
3. energy source for respiration

Question 18

Explain how the fatty acids in phospholipids allow the formation of membranes

Answer 18

-fatty acid tails = hydrophobic
-repels water molecules
-forms bilayer by facing inwards

Question 19

What is meant by hydrolysis in terms of triglycerides molecules?

Answer 19

-uses water to break 3 ester bonds

Question 20

Describe how a method that uses Benedict’s reagent and a colourimeter could be calibrated to measure the concentration of lactose in an unknown sample

Answer 20

-set to 0
-using blank
-use known contractions of glucose
-construct calibration curve
-read from curve to determine concentration

Question 21

Suggest how you could test for the prescene of a disaccharide

Answer 21

-benedicts test
-boil with HCL and retest with benedicts

Question 22

What bond holds together alpha glucose and fructose?

Answer 22

1-6 glycosidic bond

Question 23

State the name of the monomer in cellulose

Answer 23

-beta glucose

Question 24

What bond joins monosaccharides together?

Answer 24

-glycosidic

Question 25

Name the carbohydrate molecules used to store energy in plants and animals

Answer 25

plants: starch
animals: glycogen

Question 26

Describe and explain how the structure of different carbohydrate and lipid molecules suit them to their role as energy storage molecules in plants and animals

Answer 26

carbs
-polymers of glucose
-glucose used in respiration for energy
-1-4 glycosidic bonds are easy to make and break
-amylose is unbranched - no need for release in plants

lipids
-insoluble - doesn’t affect WP
-long carbon chains = can be broken down to release carbon

Question 27

How is cholesterol similar in structure to glucose

Answer 27

-both contain C and H
-contain OH groups

Question 28

State the physical property of glucose that allows it to be easily transported in the bloodstream

Answer 28

-soluble in water

Question 29

Explain why mammals store glycogen instead of glucose

Answer 29

-insoluble in water = doesn’t effect WP
-store lots of energy
-broken down rapid to release glucose

Question 30

What are 3 differences between lactose and maltose?

Answer 30

lactose
-beta
-B glycosidic
-opposing orientation

maltose
-alpha
-a glycosidic
-same direction

Question 31

Name 3 properties of cellulose that make it suitable as the basis of plant cell walls

Answer 31

1. insoluble
2. flexible
3. unreactive

Question 32

Why is glucose transported easily in animals?

Answer 32

-soluble

Question 33

How is glycogen different to amylopectin to make it better suited as an energy store in animals

Answer 33

-glycogen is more branched
-less space needed for storage
-speeds up glucose release

Question 34

Describe the differences between callose and cellulose structure

Answer 34

-callose = branched and has 1-3 and 1-6 bonds