unit 1-molecules answers

8/6/2019 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


27/27

(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]

unit 1-molecules answers

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