2.1.2 Biological Molecules

Question 1

monomer

Answer 1

a small molecule which binds to many other identical molecules to form a polymer

Question 2

polymer

Answer 2

a larger molecule made up of monomers chemically bonded together

Question 3

covalent bond

Answer 3

strong bond formed when electrons are shared between 2 atoms

Question 4

condensation reaction

Answer 4

occurs when 2 molecules are joined together with the removal of water
a covalent bond is formed

Question 5

hydrolysis reaction

Answer 5

splitting a polymer apart with the addition of water
a covalent bond is broken

Question 6

chemical elements of carbohydrates

Answer 6

carbon, hydrogen, oxygen

Question 7

monomer of carbohydrates

Answer 7

monosaccharide (eg. glucose)

Question 8

polymer of carbohydrates

Answer 8

polysaccharide (eg. glycogen)

Question 9

chemical elements of proteins

Answer 9

carbon, hydrogen, oxygen, nitrogen (sulfur)

Question 10

monomer of proteins

Answer 10

amino acid

Question 11

polymer of proteins

Answer 11

polypeptide (eg. haemoglobin)

Question 12

polypeptide

Answer 12

many amino acids joined together by peptide bonds

Question 13

chemical elements of nucleic acids

Answer 13

carbon, hydrogen, oxygen, nitrogen, phosphorus

Question 14

monomer of nucleic acids

Answer 14

nucleotide

Question 15

polymer of nucleic acids

Answer 15

DNA
RNA

Question 16

chemical elements of lipids

Answer 16

carbon, hydrogen, oxygen

Question 17

chemical symbol for calcium ion

Answer 17

Ca 2+

Question 18

functions of Ca 2+

Answer 18

nerve transmission
muscle contraction
bone formation
cofactor in blood clotting

Question 19

chemical symbol for sodium ion

Answer 19

Na+

Question 20

functions of Na+

Answer 20

nerve transmission
affects reabsorption of water in kidneys

Question 21

chemical symbol for a potassium ion

Answer 21

K+

Question 22

functions of K+

Answer 22

nerve transmission
in guard cells as a part of the stomatal opening mechanism

Question 23

chemical symbol for hydrogen ion

Answer 23

H+

Question 24

functions of H+

Answer 24

involved in ATP formation in photosynthesis & respiration

Question 25

chemical symbol for ammonium

Answer 25

NH4 +

Question 26

functions of NH4 +

Answer 26

needed for the production of nitrates by nitrifying bacteria produced in the deamination of amino acids

Question 27

chemical symbol for nitrate

Answer 27

NO3 -

Question 28

functions of NO3 -

Answer 28

used as a source of nitrogen in plants to make amino acids absorbed by root hair cells

Question 29

chemical symbol for hydrogen carbonate

Answer 29

HCO3 -

Question 30

functions of HCO3-

Answer 30

involved in the transport of CO2 regulation of blood pH

Question 31

chemical symbol for chloride

Answer 31

Cl-

Question 32

functions of Cl-

Answer 32

cofactor for amylase enzyme chloride shift in red blood cells

Question 33

chemical symbol for phosphate

Answer 33

PO4 3-

Question 34

functions of PO4 3-

Answer 34

bone formation component of ATP and nucleic acids component of phospholipids

Question 35

chemical symbol for a hydroxide ion

Answer 35

OH-

Question 36

functions of OH-

Answer 36

regulation of blood pH

Question 37

polar molecule

Answer 37

uneven charge distribution partial positive and negative charges which do not cancel out

Question 38

structure of water

Answer 38

covalent bonds within one molecule. hydrogen bonds between the molecules

Question 39

water is a liquid at room temperature

Answer 39

provide a habitat a major component of tissues reactions medium for chemical reactions effective transport medium

Question 40

properties of water

Answer 40

**chemical:** polar molecule - uneven charge distribution hydrogen bonds between water molecules hydrogen bonds are weak, large number of bonds collectively strong **physical:** ice insulates water below/ice freezes liquid water is more dense than solid water (ice) solvent for polar molecules cohesion adhesion high surface tension transparent

Question 41

water is more dense than ice

Answer 41

ice floats so ponds are insulated against extreme temperatures which decreases heat loss - aquatic organisms have a stable environment ice creates another habitat for animals e.g. polar bear

Question 42

structure of ice vs water

Answer 42

ice: open lattice structure, hydrogen bonds are stable water: hydrogen bonds break and reform

Question 43

water is a solvent for polar molecules

Answer 43

molecules can move around in a solution and react together molecules and ions can be transported when dissolved removal of waste

Question 44

water and non-polar molecules allow hydrophobic interactions to occur

Answer 44

allows tertiary structure of proteins to form allows phospholipid bilayer to form

Question 45

cohesion

Answer 45

the attraction of water molecules to one another

Question 46

surface tension (of water)

Answer 46

the surface of water's ability to resist force

Question 47

cohesion and surface tension enables

Answer 47

columns of water to be pulled up the xylem insects to walk on water

Question 48

water has a high specific heat capacity

Answer 48

hydrogen bonds restrict the movement of water molecules so a large amount of energy is required to raise the temperature

Question 49

high specific heat capacity of water means

Answer 49

water does not warm up or cool down easily water keeps a stable temperature, giving aquatic organisms a stable environment in which to live gases remain soluble in water

Question 50

water has a high latent heat of vaporisation

Answer 50

hydrogen bonds mean large amounts of energy are required for water to evaporate

Question 51

high latent heat of vaporisation in water

Answer 51

helps keep temperature stable and cool organisms plants are cooled in transpiration

Question 52

general formula for carbohydrates

Answer 52

Cx(H2O)y

Question 53

types of carbohydrates

Answer 53

monosaccharides, disaccharides, polysaccharides

Question 54

functions of carbohydrates

Answer 54

energy source energy store structural role part of larger molecules

Question 55

general formula for monosaccharides

Answer 55

(CH2O)n where n = 3-9

Question 56

properties of monosaccharides

Answer 56

soluble in water -polar OH groups insoluble in non-polar solvents tastes sweet

Question 57

isomers of monosaccharides

Answer 57

same molecular formula, different structural formula e.g. alpha glucose and beta glucose

Question 58

displayed formula of alpha glucose

Answer 58

OH group is below the plane of the axis

Question 59

role of alpha glucose

Answer 59

energy source component of starch and glycogen - acts as an energy store

Question 60

displayed formula of beta glucose

Answer 60

OH group is above the plane of the axis

Question 61

role of beta glucose

Answer 61

energy source acts as a component in cellulose - provides structural support in plant cell walls

Question 62

displayed formula of ribose

Answer 62

4 OH groups

Question 63

role of ribose

Answer 63

component of RNA and ATP

Question 64

displayed formula of deoxyribose

Answer 64

3 OH groups, 1 H off carbon-2

Question 65

role of deoxyribose

Answer 65

component of DNA

Question 66

solubility of glucose

Answer 66

freely soluble in water - polar soluble in blood plasma, can be transported to cells for uptake

Question 67

disaccharides

Answer 67

formed by two monosaccharides joining together in a condensation reaction a glycosidic bond is formed

Question 68

general formula for disaccharides

Answer 68

C12H22O11

Question 69

maltose

Answer 69

alpha glucose + alpha glucose formed in a condensation reaction with the removal of water

Question 70

sucrose

Answer 70

alpha glucose + frictose

Question 71

lactose

Answer 71

alpha glucose + beta glucose

Question 72

cellubiose

Answer 72

beta glucose + beta glucose

Question 73

reducing agent

Answer 73

a chemical species that donates an electron to an electron recipient, reducing the recipient

Question 74

oxidising agent

Answer 74

a substance that gains an electron from a reducing agent, oxidising the reducing agent

Question 75

test for reducing sugar

Answer 75

add benedict's solution heat in water bath

Question 76

positive result for reducing sugar

Answer 76

colour change from blue to green-yellow-orange to brick red

Question 77

qualitative

Answer 77

a positive or negative result tells us if a particular substance is present

Question 78

quantitative

Answer 78

tells us how much of a substance is present

Question 79

why is **excess** benedict's used when testing for reducing sugar

Answer 79

to ensure all sugar will react

Question 80

equation for volume of stock solution required

Answer 80

(total volume wanted/conc. of stock solution) x conc. wanted

Question 81

validity

Answer 81

it is suitably designed to answer the question being asked testing what is being tested

Question 82

polysaccharides

Answer 82

polymers which consist of hundreds or thousands of monosaccharides joined by condensation reactions resulting in glycosidic bonds

Question 83

examples of polysaccharides

Answer 83

cellulose, glycogen, starch, callose

Question 84

starch

Answer 84

polymer of alpha glucose made up of two components, amylose and amylopectin

Question 85

amylose

Answer 85

1,4 glycosidic bonds between carbon-1 and carbon-4

Question 86

amylose helix

Answer 86

coil = more compact shape held together by hydrogen bonds

Question 87

properties of lipids

Answer 87

insoluble in water high in energy

Question 88

differences between saturated and unsaturated fatty acids

Answer 88

S: single C-C bonds, max. hydrogens, solid at room temperature, high melting point U: 1 < double C=C bond, not max. carbons, low melting point

Question 89

structure of a triglyceride

Answer 89

3 fatty acids, 1 glycerol

Question 90

functions of triglycerides

Answer 90

energy source energy store insulation buoyancy protection

Question 91

triglyceride as an energy source

Answer 91

ester bonds can be hydrolysed to form 1 glycerol and 3 fatty acids used in respiration and release energy

Question 92

triglyceride as an insoluble energy store

Answer 92

can be stored without affecting the water the water potential of cells

Question 93

triglycerides as an energy store: high energy density

Answer 93

they have a greater proportion of hydrogen atoms compared to carbohydrates

Question 94

triglycerides as a heat insulator

Answer 94

whales have blubber (adipose tissue)

Question 95

triglycerides as an electrical insulator

Answer 95

fatty myelin sheath around some neurones. insulates and increases conduction speed of impulses

Question 96

triglycerides - buoyancy

Answer 96

fat is less dense than water aquatic organisms can float. eg. frogs

Question 97

triglycerides - protection

Answer 97

fat acts as a shock absorber around delicate organs

Question 98

test for lipids

Answer 98

emulsion test

Question 99

structure of a saturated fatty acid

Answer 99

no double bonds

Question 100

structure of an unsaturated fatty acid

Answer 100

at least one double C=C bond

Question 101

simplified structure of a phospholipid

Answer 101

hydrophilic phosphate head hydrophobic fatty acid tail

Question 102

structure of a phospholipid

Answer 102

Question 103

amphipathic

Answer 103

both hydrophobic and hydrophobic parts

Question 104

phospholipid fatty acid tails

Answer 104

non-polar hydrophobic move away from water and interact with each other

Question 105

phospholipid phosphate heads

Answer 105

polar hydrophilic interact with water extracellularly and intracellularly

Question 106

structure of cholesterol

Answer 106

Question 107

function of cholesterol

Answer 107

regulates and maintains the fluidity of the membrane

Question 108

cholesterol at high temperatures

Answer 108

it stabilises the membrane and raises the melting point

Question 109

cholesterol at low temperatures

Answer 109

it intercalates between the phospholipids and prevents clustering

Question 110

without cholesterol, the bilayer is too hot

Answer 110

too fluid/flexible won't hold shape

Question 111

functions of proteins

Answer 111

an essential component of cell membranes antibodies enzymes form structural components of animals

Question 112

structure of an amino acid

Answer 112

amine group, carboxylic group, hydrogen atom, R group

Question 113

a zwitterion

Answer 113

a compound with no overall electrical charge, which contains separate parts which are positively and negatively charged

Question 114

a buffer

Answer 114

a substance that helps to resist large changes in pH

Question 115

basis of the test for protein

Answer 115

a test for peptide bonds colour formed by a complex between the nitrogen atoms in the peptide chain and the Cu 2+ ions

Question 116

primary structure of a protein

Answer 116

sequence of amino acids held together by peptide bonds

Question 117

secondary structure of a protein

Answer 117

folding of amino acid chain into alpha helix or beta pleated sheet due to hydrogen bonding between amino acids

Question 118

tertiary structure of a protein

Answer 118

folding of the secondary structure to form a specific (3D) shape. 4 different types of bonding/interactions can hold this shape together

Question 119

two types of secondary structure of a protein

Answer 119

alpha helix beta pleated sheet

Question 120

quaternary structure of a protein

Answer 120

a protein which is made up of 2 or more polypeptide chains. 4 different types of bonding/interactions can hold this shape together

Question 121

examples of fibrous proteins

Answer 121

keratin, elastin, collagen

Question 122

examples of globular proteins

Answer 122

antibodies, hormones, enzymes

Question 123

4 different types of bonding/interactions in protein structure

Answer 123

ionic disulfide hydrogen hydrophilic/hydrophobic

Question 124

primary structure of a fibrous protein

Answer 124

repetitive regular sequence of amino acids

Question 125

primary structure of a globular protein

Answer 125

irregular amino acid sequence

Question 126

shape of fibrous protein

Answer 126

long parallel polypeptide chains cross-linked at intervals from long fibres

Question 127

shape of globular proteins

Answer 127

folded into a spherical shape

Question 128

stability of fibrous proteins

Answer 128

stable structure - unreactive

Question 129

solubility of fibrous protein

Answer 129

insoluble

Question 130

solubility of globular proteins

Answer 130

easily soluble - hydrophilic R groups point outwards

Question 131

stability of globular proteins

Answer 131

relatively unstable structure

Question 132

function of fibrous proteins

Answer 132

support + structural functions

Question 133

function of globular proteins

Answer 133

metabolic functions

Question 134

properties of collagen

Answer 134

provides high mechanical strength due to covalent bonds linking triple helix molecules together flexible and insoluble found in the outer wall of artery where it prevents bursting under high pressure

Question 135

properties of elastin

Answer 135

strong and can stretch and recoil without breaking insoluble found in alveolar walls where it allows them to stretch during inhalation and recoil during exhalation to expel air found in blood vessel walls, skin

Question 136

properties of keratin

Answer 136

very strong molecule - lots of disulfide bonds, the degree of these determines flexibility insoluble mechanical protection waterproof found in hair, skin, nails, claws, hoofs, scales, horns, fur, feathers