Download - Unit 1-Molecules Answers
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1.
Disaccharide Constituent Monomers One role in livingorganisms
Glucose and galactose
Maltose Energy / food source in(germinating) seeds
Sucrose Glucose and fructose
[5]
2. (a) (Linear) sequence / order / arrangement / pattern of amino acids ; 2
(b) Description of H bond / attraction between dipoles e.g + and / weak electrostatic bond
Between H and O;
In amine and carboxyl groups
Reference to the helix / secondary structure / - sheet/ strand ;
(Bond between) R groups in coiling / tertiary stucture / 3D shape Max 3
(c) Long chain / long strand / fibrils / reference to linear molecule
Repeating sequence of amino acids;
Many parallel strands lie side by side / eq;
Reference to a helix / (pleated) sheet;
Collagen has triple helix; Max 3[8]
3. Condensation / polymerisation ;
Deoxyribose ;
Thymine ; [watch spelling]
(double) helix ;
Hydrogen ; [accept H][5]
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4. amino acids / polypeptides / peptides ;peptide ; [not dipeptide] [accept peptide / hydrogen / disulphide / ionic if peptide orpolypeptides given above]
condensation / polymerisation ;
( ) helix / (alpha) helix ;hydrogen / H ;
[5]
5. (a) A phosphate ;B pentose / ribose / deoxyribose / 5C sugar ;C purine / pyrimidine / (organic) base / named example ; [watch spelling] 3
(b) U C G G C A G G G C A G ; ;[one mistake = 1 mark, two mistakes = 0] 2
(c) making new DNA / copying DNA ;makes identical copies ;new molecule has one old and one new strand ;DNA strands separate / eq ;each strand acts as a template ;individual nucleotides line up against (old) strand ;complementary base pairing ;nucleotides joined (by DNA polymerase) ; 4
(d) one eighth / 12.5% ;eight strands have been formed from each original strand / eq ; 2
(e) interphase / S phase ; 1[12]
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6.
Statement Sucrose Maltose
Contains glucose
Is a reducing sugar
Contains glycosidic bonds
Is transported in thephloem of flowering plants
Encircle CORRECT answersAny TWO correct responses = 1 mark Blanks and ambiguous ticks are incorrectPut correct numbers of ticks to correspond with total mark
[4]
7. H2O ;(di)polar ;Hydrogen / H ;Solvent ;(specific) heat capacity ;
[not latent heat capacity]
[5]
8. (a) Making more DNA ;Molecule unwinds / strands separate ;Each strand acts as a template / eq ;Each molecule contains, one parental/ one new / one daughter strand ;New DNA is identical to original DNA / identical to each other / eq ; max 3
(b) Folding of secondary structure / eq ;To form irregular / 3D / globular shape ;Maintained by, hydrogen / ionic / disulphide bonds / eq ;Bonding determined by R-groups ;Shape is important for function ; max 3
[6]
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9. ACCEPT POINTS ONLY IN CORRECT CONTEXT
1. Contain carbon, hydrogen and oxygen ;2. Insoluble (in water) / hydrophobic ;3. Triglycerides consist of glycerol plus three fatty acids ;
4. Joined by condensation reactions / formation of ester bonds ;5. Correct reference to saturated and unsaturated fatty acids ;6. Phospholipids consist of glycerol plus two fatty acids and a phosphate group ;7. Reference to non-polar/hydrophobic tails/fatty acids and polar/hydrophilic
heads/phosphates of phospholipids ;
8. Correct orientation of phospholipids, in cell membrane / phospholipids bilayer ;9. Role of phospholipids in cell membrane (fluidity/permeability etc) / role of
surfactants ;10. Energy stores ;11. Reference to energy from fats / oils, compared with carbohydrates ;
12. (mechanical) protection / packing qualified ;13. Insulation qualified (either electrical or thermal) ;14. Buoyancy ;15. Qualified reference to waterproofing / protection against entry of pathogens in plants ;
[10]
10.
Component DNA mRNA
Cytosine present
Uracil present
Pentose sugar present
Is single stranded
[Any two correct = 1 mark][Blanks and alterations are incorrect]
[4]
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11. Sequence / order ;Peptide ;Condensation / polymerisation ;Hydrogen / H ;(di)sulphide / covalent ; [accept sulphur]
R groups / side chains / sulphur / SH groups / thiol groups ;[6]
12. (a) Breaks the hydrogen bonds (between the strands) ; 1
(b) Condensation / polymerisation ; 1
(c) Interphase / S phase / synthesis phase ; 1[3]
13. (a) {Fatty acid / tails} are {hydrophobic / non-polar} ;(so orientate themselves) away from {water / polar environment} ;{Phosphate / heads} are {hydrophilic / polar} ;(so can) interact with {water / polar environment} ; 3
(b) Correct measurement ; [27 mm or 37 / 38 mm]Divide by magnification ;Correct conversion to m ; [answer = 0.009 or 0.012 / 0.013] 3
(c) Carbohydrate: Cell
Protein: Transport of molecules / eq ORreceptor for hormone / eq OR enzymes ; 1
recognition / cell adhesion / eq ; 1
[8]
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14.
Name of molecule Formula Structure
OH H ;
Amino acid HH
CO
OHN
RH
C ;
CH 3 (CH 2)4 COOHOR
C5 H11 COOH ;
( ) Glucose / hexose ; C6 H12 O6 ;
[6]
15. (a) Glycerol; 1
(b) (i) (mono)unsaturated;[reject: polyunsaturated] 1
(ii) Softer / more likely to be liquid / less densely packed
molecules / eq; 1
(c) Bilayer;Heads outward and tails inward; 2
[5]
16. (a) (i) Glycerol / propan 1, 2, 3 triol 1
(ii) Ester 1
(b) (Stearic acid / saturated fatty acids} have more hydrogen atoms;{Stearic acid / saturated fatty acids} have no double carbon-carbon bonds;{Stearic acid / saturated fatty acids} have no kinks;[allow converse statements about unsaturated fatty acids] 2
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(c) 1. Energy stores;Qualification: {More than / twice as much as) carbohydrate
OR Insoluble / compact / minimise massOR Subcutaneous / adipose / blubber;
2. Protection / mechanical insulation;Qualification: Around {organs / named organ}OR Reference to adipose tissueOR Ear wax giving protection against infection;
3. Waterproofing;Qualification: Of skin / fur / feathers / insect cuticle / ear wax
OR Hydrophobic / insoluble / repels water;
4. Electrical insulation;Qualification: Reference to myelin sheath / nerve cells /
neurones / axons / dendronsOR Non-polar;
5. Heat insulation;Qualification: Subcutaneous / adipose / blubber
OR Prevents heat loss from body;
6. Buoyancy;Qualification: Less dense than {water / muscle};
7. Making beeswax;Qualification: Formation of honeycomb;
8. Membrane fluidity;Qualification: Reference to cholesterol;
9. Cell membrane structure;Qualification: Reference to phospholipids;
10. Reference to hormones;Qualification: As steroids;
11. Source of metabolic water;Qualification: Reference to respiration
OR Desert adaptation 2 x 2 mark [8]
17. (a) 1. Contains (r)RNA;
2. And protein;
3. Has two (sub-)units;
4. Binding{site/groove} to accept RNA;
5. 20-30 nm in size; 2
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(b) Glycine;Lysine; 2
(c) (i) N C C N C C
HH
H
H
H
OH
R RO
O
Correct amino acid parts on either side;;Carbon nitrogen back bone; 3
(ii) Condensation 1[8]
18. (a) 1. Compact / eq;
2. {Polymer / eq} of glucose;
3. Can be (easily) hydrolysed / can be brokendown to release energy;
4. Insoluble / does not affect osmosis / eq;
5. Will not diffuse out of cells / will remain in cells; max 2
(b) (i) Correct glucose structure for each molecule where thereaction is taking place;; 2
(ii) Hydrolysis; 1[5]
19. (a) (i) W Guanine / G;
X Nucleotide;
Y Phosphate / phosphoric acid;
Z Deoxyribose / pentose sugar / 5C sugar; max 4
(ii) Hydrogen; 1
(b) (i) Transcription; 1
(ii) Aspartic acid, Arginine, Cysteine, Lysine; 1
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(iii) 1. Incorrect amino acid inserted into polypeptidechain / {chain / sequence} of amino acids changed;
2. Named {Gly / glycine};
3. Different {side group / R group / eq};
4. Different bonds formed;
5. Different (3D) shape when folded / eq; 3[10]
20. (a) Hydrogen / H 1
(b) Charge is not equally distributed throughout molecule / one part is
positive and the other part is negative};Hydrogen (atoms) have (slight) positive charges;Oxygen (atom) has a (slight) negative charge ; 2
(c) Idea that a lot of {energy / heat} is needed to change temperature ;Temperature of their {environment / habitat} does not {fluctuate / change}much / reference to {thermostable / thermobuffer};Reference to effect on metabolic {rate / reactions}; 2
[5]
21. (a) (i) Nucleus / nucleoplasm; [allow nucleolus] 1
(ii) Condensation / polymerisation 1
(b) (i) 6; 1
(ii) GCT TGG CGG GCT TAG TGG;;[all correct = 2 marks, one error = 1 mark, more than one error = 0 marks] 2
(c) Reference to start codon;Reference to stop codon;Reference to post transcription modification; 2
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(d) 1. Occurs {on / in} ribosome;
2. Two
3. Each carrying a specific amino acid;
tRNA molecules (held in position in ribosome);
4. Anticodons on tRNA;5. Reference to binding of tRNA to complementary bases on mRNA;
6. Peptide bonds form between amino acids;
7. Ribosome moves along mRNA;
8. Until a stop codon is reached 5[12]
22. (a) 1. Making more DNA;
2. Strands separate ;
3. Idea that each strand acts as a template / eq;
4. Nucleotides line up against complementary base pairs;
5. (Each) new (daughter) molecule contains one old and one new strand;
6. Reference to molecules being identical to {each other / original parentmolecule}; 4
(b) (i) DNA in B is lighter (than the DNA in A) converse;
Because A contains all heavy nitrogen;B contains both heavy and light nitrogen; 2
(ii) 1. (Bacteria) in B have one heavy and one light strand of DNA (in each molecule);
2. All newly synthesised strands will contain light{DNA / nitrogen};
3. Some molecules will consist of only light DNA;
4. Some molecules will consist of one light strand andone heavy strand;
5. Each type of molecule is present in equal proportions; 3
(iii) Two bands shown in correct position;Lower band is thinner than the one shown in D and upper band isthicker than one shown in D; 2
[11]
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23. (a) (i) Hydrogen;Ionic;Disulphide; 2
(ii) It has two (polypeptide) chains / an A and a B chain / more than
one (polypeptide) chain; 1
(b) (i) {Sequence / order} of amino acids; 1
(ii) 1. Reference to bonds between R groups;
2. The R groups are always in the same position;
3. [Bonds / named bonds} will always form in the same place;
4. Reference to {hydrophilic groups on outside / hydrophobicgroups on inside}; 2
[6]
24. (a) 4
Statement Starch Glycogen Monosaccharide
Is a polymer
Glycosidic bonds arepresent
Is an energy store in animalcells
Has high solubility in water
[One mark for every two correct]
(b) 30; 1
(c) 1. DNA {uncoils / separates / unzips} / hydrogen bonds break / eq;
2. (Template) strand used to form {mRNA / complementary strand} / transcription;
3. Reference to RNA polymerase;
4. mRNA passes {to ribosome / out of nucleus / to the cytoplasm};
5. tRNA picks up specific
6. Codon and anticodon binding;
amino acid;
7. Correct reference to {start / stop} codons;
8. Peptide bonds forming between amino acids;
9. Example of correct complementary base pairing; 5
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(d) (Different) R groups;
Determine bonds formed between R groups of different amino acids;
Named bond between R groups, e.g. S=S / H / etc; [not peptide]
Reference to {secondary / tertiary} structure; 2[12]
25. (a) (i) COOH; 2
C
O
H ;;
(ii) Saturated;
No double bonds in (hydrocarbon) chain; 2
(b) (i) Anything that {affects / raises} the chance of harm / eq; 1
(ii) 1. Strain on the heart;
2. Raises blood pressure;
3. Raises cholesterol / LDL (in the blood);
4. Increased risk of formation of {atheroma / plaques};
5. Atherosclerosis / atherosclerosis explained / eq;
6. Increased risk of type 2 diabetes / explained; 3
(c) 1. Glucose is {a monosaccharide / soluble / doesnt need to be digested} / eq;
2. Glucose can be quickly absorbed into the blood stream;
3. Can pass into muscle (cells);
4. Can be used for respiration;
5. To provide energy;
6. For (muscle) contraction; 3[11]
26. (a)
Disaccharide Monosaccharide
Galactose Glucose Fructose
Sucrose
Maltose
Lactose
[One mark for each correct row] 3
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(b) Glycosidic; 1[4]
27. Nitrogen / N;
Peptide;
{Alpha / } helix;
Hydrogen / H;
R groups / side groups / side chains;[5]
28. (a) (i) Water; 1(ii) Active site; 1
(iii) Glycosidic bond; 1
(b) (i) Sucrase {has a (specific) tertiary structure / is a protein};
Reference to specific shape
Only sucrose will fit (the active site of sucrase) / enzymes are specificto substrate / correct reference to lock and key;
of active site;
Form an enzyme-substrate complex;Correct reference to induced fit; 3
(ii) Facilitated diffusion;
Use of (specific carrier) proteins / moves molecule down aconcentration gradient / correct reference to kinetic theory;
OR
Active transport;
Use of (specific) carrier proteins / moves molecules against agradient / uses {ATP / energy};
OR
Endocytosis;
Description of endocytosis e.g. formation of vesicle / use of ATP / eq; 2[8]
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29. (a) Water ; 1
(b) Correctly drawn 6membered ring O
CC
O
C C
ORC
;
OH group on carbon 1 below
(O)
C
OH
the ring
;
Rest of molecule drawn correctly
OHC
O
OHOH
OH
OH
;
[Accept correct vertical or horizontal transposition] 3
(c) Energy source / eq ;
Idea that it is a source of glucose ;
In germinating seeds ; 2[6]
30. (a) Phosphate and base joined to pentose sugar twice ;
Base correctly joined to sugar ;
Phosphate joined to two sugars ; 3
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(b) 1. Held by hydrogen bonds (holding 2 strands together) ;
2. {Between complementary base pairs / detail of base pairing} ;
3. Reference to {5 to 3 and 3 to 5 strands / anti-parallel strands / DNApolymerase}
4. Reference to double helix ;
5. Reference to association of DNA with histones ;
6. Called chromatin ;
7. Reference to nucleosomes ;
8. Further {folding / coiling} / ref to scaffold proteins ; 5
(c) (i) Cytosine : 36 ;
Guanine : 36 ;
Thymine : 14 ; 3
(ii) 50 (%); 1[12]
31. (a) 7
Chemical
compound
One example of thechemical compound
found in living organisms
Subunit(s) of the
chemical
Elementscontained inthe chemical
PolysaccharideStarch / Glycogen /
Cellulose / Amylose / Amylopectin;
Monosaccharide / Glucose / named
monosaccharide eg glucose;
C,H,O;
Protein Enzyme Amino acid; C,H,O,N,S
Lipid Phospholipid Fatty acids and C,H,OGlycerol;
Nucleic acid DNA/RNA; Nucleotide C,H,O,N,P
(b) Unsaturated contain one or more (C=C) double bonds / eq; 1
(c) Diagram showing a bilayer of phospholipids;
Heads on outside and tails on inside [Must have two tails];
Proteins included in the diagram; [distinguishable from thephospholipids, can be intrinsic, extrinsic or transmembranewith suitable label] 3
[11]
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32. (a) (i) 0.14% / 0.07% per year; 1
(ii) 3.9 - 4 times; 1
(b) (i) The greater the BMI the greater the chance of dying due tocoronary heart disease / eq;
Correct reference to figures; 2
(ii) BMI =metres)in(height
kg)(inmassbody)(2
; 1
(iii) 1. Fatty deposits in arteries / atheroma / plaques / reference to atherosclerosis;
2. Higher cholesterol levels;
3. Higher blood pressure;4. Risk of damage to (coronary) arteries;
5. Risk of blood clot blocking coronary
6. Risk of type II diabetes; 3
arteries;
[8]
33. (a) (i) Relates to the sequence of amino acids
(ii) 1. Reference to R groups;
/ eq; 1
2. Reference to (specific) folding of the chain / tertiary structure / eq;
3. Reference to named bonds [not peptide]; 2
(b) 1. Enzymes have a (specific) active site
2. Will only fit substrate with the correct
;
shape
3. Reference to lock & key / enzyme-substrate complexes / induced fit; 2
/ eq;
(c) 1. Correct reference to translation;
2. mRNA lines up at the ribosome / eq;
3. tRNA attaches to specific amino acids / eq;
4. Codon - anticodon binding / complementary base pairing betweenmRNA and tRNA;
5. Peptide bond;
6. Correct reference to start / stop codons; 4[9]
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34.
Statement DNA mRNA
Double stranded
Adenine and uracilPentose sugar
Phosphodiester[Any 2 correct = 1 mark]
[4]
35. 1 Energy store ;
2 Heat insulation / protection / buoyancy / energy store ;
3 Heat insulation / protection / buoyancy /energy store ;
4 Waterproof/eq ;[4]
36. (a) Peptide bond drawn correctly ;
Rest of both amino acids drawn correctly ; 2
(b) (i) Reference to -helix / -pleated sheet ;Reference to hydrogen bonds ; 2
(ii) 1. The primary structure is the same length at both temperatures ;2. The secondary structure is shorter at 25 C ;3. Length decreases from primary to secondary at both
temperatures ;4. Correct manipulation of figures ; 2
(iii) 1. Reference to increase in kinetic energy at (55 C) ;2. (More) vibrations within molecule ;3. Therefore hydrogen bonds (holding -helix / -pleated
sheet together) reak/eq;4. (Molecule) starts to unwind ; 2
[8]
37. (a) (i) condensation 1
(ii) glycosidic 1
(iii) water; 1
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(b) (i) An explanation to include two from:
1. compact therefore large numbers of molecules can fitin a small space / eq
2. insoluble therefore osmotically inactive / eq
3. large molecule therefore remains within cells / cannot pass through membranes / contains a tot of energy
4. easily hydrolysed when required for energy /eq 2
(ii) glycogen has side branches only / more side branches / starch composed of two components / amylose and amylopectin 1
[6]
38. (a) (i) adenine 1
(ii) uracil 1
(iii) phosphate 1
(b) A description to include two from:
1. double [ / helix]
2. base pairing / A-T,C-G
3. hydrogen bonds (easily broken) 2
(c) Any two from:
1. DNA replication - both strands copied / transcription only one strand copied
2. DNA replication uses T, transcription uses U
3. Reference to DNA polymerase / RNA polymerase
4. DNA replication copies whole strand / transcription only copies part of the strand / eq
5. mRNA synthesised in transcription, not in DNA 2 [7]
39. (a) (i) CNH; 1
(ii) peptide 1
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(b) An explanation to include two from:
1. chain folds into secondary structure / reference to a-helix or 3 pleated sheets
2. then folds into tertiary structure
3. [ / interactions) between R groups
4. reference to named bond
Reject peptide 2
(c) (i) An explanation to include:
1. substrate concentration limiting the rate / eq or converse
2. correct reference to not all active sites occupied by substrate / eq 2
(d) An outline to include four from:
1. identify independent variable and dependent variable
2. select suitable range of concentrations (at least 5);
3. fixed volumes of enzyme / substrate
4. control of named variable(s)
5. description of apparatus used
6. correct method of obtaining quantitative results
7. reference to replication / calculation of rate / mean values 4[10]
40. 1. Covalent;
2. Dipole / dipolar; NOT polar / bipolar
3. Solvent;
4. Hydrogen / H; NOT H2
5. (Specific) heat capacity; NOT latent heat
[5]
41. (a) (i) Hydrogen / H; 1
(ii) Amino acid; 1
(iii) 1. A {triplet of / three} bases (on tRNA);
2. complementary to codon (on mRNA) / complementary to thetriplet on mRNA; 2
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(b) 1. tRNA molecule is {folded/cloverleaf shape/L-shaped}but mRNA is a {straight chain / hairpin loop};
2. tRNA is a fixed length but mRNA molecules are of variablelength / eq;
3. tRNA molecule is (usually) a short chain but mRNA is(usually) longer;
4. tRNA molecule contains (regions of) {hydrogen bonds / H bonds / double-stranded regions} within it;
5. Ref. to modified base (or named modified base) in tRNA; 2[6]
42. (a) (i) 7; 1
(ii) 1. UCUGA;
2. TCTGA; 2
(b) 1. (%) adenine must equal (% of) thymine;
2. (double figure) 58.8;
3. Guanine and cytosine must make up rest of molecule / eq;
4. (subtract from 100) = 41.2;
5. (% of) guanine = (% of) cytosine / eq;
6. (divide by 2) = 20.6;
OR
1. Adenine (and guanine) are purines;
2. purines bind to pyrimidines;
3. (purines) must equal 50%;
4. Guanine = {50 29.4 / 20.6};
5. Guanine and cytosine bind together;
6. Therefore cytosine = 20.6(%);
OR
1. Adenine binds with thymine;
2. Therefore thymine = 29.4 (%);
3. Thymine and cytosine are pyrimidines;
4. Thymine + cytosine = 50 (%);
5. 50 29.4;
6. Cytosine = 20.6(%); 5[8]
43. (a) (i) COOH group;
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NH 2 group;ACCEPT correct structures drawn out 2
(ii) An explanation to include three from:
1. appropriate reference to {secondary structure /
-helix or -pleated sheet};2. polypeptide chain folded in a specific shape / reference
to tertiary structure;
3. reference to R groups;
4. bonding between R groups determines the shape;
5. named bond ie. hydrogen, disulphide, ionic; 3
(b) (i) 6; 1
(ii) transcription; 1
(iii) AUG CCA UAC GGU UGG AAG;;
[1 mark if T instead of U given] 2 [9]
44. (a)Polysaccharides Lipids Proteins
Are polymers
Have ester bonds
Contain carbon, hydrogen, oxygenand nitrogen
Form components making up thestructure of cell membranes
12 correct 6 marks11 or 10 correct 5 marks9 or 8 correct 4 marks7 or 6 correct 3 marks5 or 4 correct 2 marks3 or 2 correct 1 mark 1 or 0 correct 0 marks 6
(b) (i) saturated (lipids) have no double bonds in the hydrocarbon chain / C = C / between carbon atoms and
saturated (lipids) from animal sources
unsaturated have double bonds / C = C
and
saturated (lipids) tend to be solid
unsaturated from plantsources
and unsaturated liquids at r.t.;
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(ii) starch has {two components / amylose and amylopectin} and
starch stored in plant cells
glycogen does not
and
glycogen has a branched structure
glycogen in animal cells
but
glycogen has more branches
{starch / amylose}has a coiled structure
than[8]
{starch / amylopectin}; 2
45. 1. covalent;
2. fatty acid;
3. glycerol / propan-1,2,3-triol / propantriol;
4. condensation;5. unsaturated;
[5]
46. 1. made of C, H, O;
2. glycerol / propan (1, 2, 3) triol;
3. three fatty acids;
4. correct location of ester {bond / link};
ACCEPT points 2, 3 and 4 made on a clearly labelled diagram 3[3]
47. (a) (i) ester; 1
(ii) hydrolysis; 1
(iii) fatty acids;glycerol; 2
(iv) unsaturated / eq are {liquid at room temperature / lower meltingpoint} whilst saturated / eq solid at room temperature;MUST be a comparative point 1
(b) (i) phosphate; 1
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(ii) ref. to {hydrophilic / charged / polar / water attracting}{head/group} and {hydrophobic /not charged / non-polar / water repelling} {tail /group } / eq;ref. to forming a bilayer;ref. to orientation in membrane; 2
[8]
48. (a) energy / glucose storage; 1
(b) (i) diagram showing 1 glucose molecule / monosaccharide;diagram shows H and OH groups on each of carbon 1 and carbon 4; 2
(ii) ref to specificity / shape;correct ref to active site on enzyme;correct ref to enzyme-substrate complex / eq;lock and key concept / induced fit;ref to amino acids in proteins versus glucose in glycogen / peptide versus glycosidic bonds; 3
(c) reduces activation energy / provides an alternative reaction pathway;(biological) catalyst / speeds up reaction without being used up;allows reactions to occur rapidly at body/lower temperature; 2
[8]
49. (a) (i) the {sequence / order} of amino acids; 1
(ii) hydrolysis; 1
(b)
CCN
H
H H O
OHCH 2
OH ; 1[3]
50. (a) A phosphateB deoxyribose; 1
(b) (i) Adenine 29, Guanine 21, Cytosine 21; 1
(ii) 1. a purine always bonds to a pyrimidine;
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2. % thymine must equal % adenine / eq;
3. guanine and cytosine must make up rest of molecule / eq;
4. % guanine = % cytosine / eq; max 3
(c) 1. DNA contains genetic information / eq;
2. DNA codes for protein / eq;
3. a change in DNA could produce a different {protein / mRNA} / eq;
4. idea that it is required throughout life (or {cell / organism});
5. idea that it is needed to pass on to next generation (of {cell / organism}); max 2
(d) 1. part of the DNA (molecule) unwinds;
2. DNA strands separate / {hydrogen / H} bonds break;
3. idea only one strand acts as a template;
4. (free) nucleotides line up against DNA;OR reference to complementary base pairing / correct description;
5. correct reference to RNA polymerase;
6. reference to {nucleotides joining together / formation of phosphodiester bonds};
7. (to form) mRNA;
8. exits through nuclear pore / from nucleus to cytoplasm / movement to ribosomes; max 5
[12]
51. (a) (nitrogenous / organic) base / named base; 1
(b) 1. 8 double strands drawn;
2. 2 hybrid and rest all light DNA; 2
(c) DNA polymerase / helicase / DNA ligase / primase / eq; 1
(d) TCG AAT GGT; 1
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(e) 1. correct reference to description of gene mutation;
2. change {mRNA / codon / eq};
3. {different / wrong / no} amino acid included / stop codon;
4. different / eq {sequence of amino acids / primarystructure of protein};
5. different R groups;
6. change bonding in protein / correctly named bond(s);
7. protein forms different {secondary / tertiary / quaternary}structure;
8. different (3D) shape; max 5[10]
52. 1. hydrophobic / non-polar / not charged;
2. glycerol / propan-(1,2,3)-triol;
3. (saturated / unsaturated) fatty acids;
4. ester / covalent;
5. insulation / buoyancy / energy store / protection / source of metabolic water;[5]
53. (a) (i)
CH 2 OH
O
CH 2 OH
OHO
H OH
H
H
H H
OH
OH H
H
H
H
H
OH OH
OH
OH
galactose; glucose 2
(ii) 1. breaking of (glycosidic) bond / eq;
2. {addition of / using} water / eq;
3. breaking larger molecule(s) into smaller molecules / named example other than lactose to glucose andgalactose OR disaccharide being broken into twomonosaccharides;
4. reference to {hydrolytic / named} enzyme; max 2
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(b) (i) 1. Parents genotypes : Gg / gG for both parentsand
2. Possible genotypes
of second child: GG Gg Gg gg;
parents gametes: G g for both parents;
3. Probability of nothaving the condition: 0.75 / 75% / ; 3
(ii) 1. more than one {triplet / codon / eq} may code for sameamino acid;
2. third base in {triplet / eq} often not important / eq;
3. at 3rd base {point mutation / base changes / eq};
4. amino acid swapped but does not change shape of
protein / eq;5. (mutation occurs) in intron / eq; max 2
(iii) 1. risk of miscarriage;
2. risk of harm to {fetus / eq} / eq;
3. reference to a fetus right to life;
4. should the pregnancy be terminated / eq;
5. {practical / financial} issues;
6. mental and emotional issues; max 3 [12]
54. (a) (i)Feature Glucose Glycogen Maltose Starch
1-6 glycosidicbonds present
Made up of many monomers
One mark per correct column. 4
(ii) lactose; 1
(iii) Award one mark for each of the following points in context toa maximum of two.
1. one unit of glucose correctly drawn;
2. second identical unit; 1
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(iv) hydrolysis; 1
(b) Award one mark for each of the following points in context toa maximum of three.
1. large molecule/made up of many monomers allowsstorage of large amounts of energy;
2. compact therefore large amounts can be stored in a cell;
3. insoluble therefore does not have an osmotic effect/eq;
4. inert so not affected by other reactions in cells;
5. large molecule therefore cannot pass out of cells;
6. can be hydrolysed to release large amounts of energy / glucose when required; Max 3
[11]