Every Biological Molecules Answer

8/12/2019 Every Biological Molecules Answer

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1.

h y d r o g e n b o n d

O O

H

HH

δ +

δ + δ

+

δ -

δ -

δ +

H

1 hydrogen bond represented as,

horizontal / vertical, dashed line between O on one molecule and H on the adjacent

molecule;

DO NOT CREDIT if >1 H bond is drawn between the same

two molecules

2 hydrogen / H, bond label (on any drawn bond between 2 molecules);

3 (delta positive) δ+ on each drawn H

and (delta negative) (2) δ

on each drawn O;

if both molecules drawn, δ+ and δ

– on all atoms.

ACCEPT d (lower case) for δ[3]

2. ice floats

P1 (ice less dense because) molecules spread out;P2 molecules !orm, crystal structure / lattice / "#;

P3 ice !orms insulating layer / clearly described;

e.g. acts as a barrier to the cold

P4 water (below ice), does not !reeze / still li$uid / remains water / %ept at higher temperature;

S1 organisms do not !reeze;

DO NOT ACCEPT die (because ‘survival stated in stem)

S2 animals / organisms, can still, swim / move;

S3 allows, currents / nutrients, to circulate;

Macmillan Academy 1



solubilit!

P5 ions / named ion, polar / charged;

P6 ions /named ion, attracted to / bind to / interact with, water;

S4 (named) organisms / plants / animals, upta%e / "#, minerals / named mineral / nutrients; ACCEPT obtain " enters " goes in " gets

S5 correct use o! named, mineral / nutrient, in organism;

needs to be more s#ecific than ‘for growth " metabolism

suitable e$am#les include but are not limited to% nitrates for

amino acids " #rotein " (named) nucleic acid " #hos#hate for

&' " #hos#holi#ids " #lasma membrane " magnesium for

chloro#h!ll etc

tem#erature stabilit!

P7 many / stable, (hydrogen) bonds between molecules;

an! h!drogen bonds between molecules * mars (gets -

and H)

P8 at lot o! energy to, !orce apart molecules / brea% bonds;

ACCEPT heat as alternative to energ!

P9 high (speci!ic) heat capacity;

DO NOT CREDIT latent heat ca#acit!

S6 temperature does not change much / small variation in temperature;

could refer to organisms or surrounding water

ACCEPT sta!s cool in summer " sta!s warm in winter

DO NOT CREDIT constant alone

S7 e!!ect o! temperature on, enzymes / metabolic rate;

ACCEPT an! reference to tem#erature affecting en!me

activit! " metabolic rate

S8 gases remain soluble;

&ward once in an! section

H hydrogen bonds;

DO NOT CREDIT if in incorrect conte$t

(e.g. the! are strong bonds)7 max

QWC & "ward i! you see a ' mar% and an mar% within the same section;

/oo for the S mar first, then award 02 if there is a P mar

in the same section in the mar scheme1

[8]

Macmillan Academy 2



3. hydrolysis / hydrolytic;

hydrophilic;

ACCEPT #honetic s#elling throughout

IGNORE head

[2]

4. (i) ;1

(ii) 1 substrate / '"*", and, inhibitor / sul!onamide, similar shape;

ACCEPT similar structure DO NOT CREDIT same

2 able to, bind / !it into / bloc%, active site;

3 (shape) complimentary to active site;

DO NOT CREDIT refs to &3& and sulfonamide being

com#lementar! to each other or to the en!me (alone)

4 both have, he / benzene / &-, (ring);

5 both have, .2 / amine;

6 correct re! to a di!!erence between sul!onamide and '"*";

e.g. onl! sulfonamide contains 4

sulfonamide has 1 more 5H grou#

sulfonamide has 465H but &3& has 5

onl! &3& has 266H grou# 3

[4]

5. (i) without inhibitor

1 more, '"*" / substrate, molecules enter active site0

ACCEPT more successful collisions between substrate and

active site

2 more, enzyme substrate complees / 1-s, !ormed;

3 at low concentration not all active sites occupied / at high

concentration all active sites occupied;

ACCEPT active sites filled " no free active sites

DO NOT CREDIT active sites run out

4 achieves / reaches, ma (turnover) rate / ma;

ACCEPT ‘cannot wor an! 7uicer

DO NOT CREDIT ‘o#timum rate or ‘rate levels off

5 (at high substrate concentration) enzyme concentration limiting;3 max

Macmillan Academy 3



(ii) with inhibitor

1 inhibitor / sul!onamide, can, !it / bloc% / bind to / compete

!or, active site;

2 (occupies it) !or a short time / temporary / reversibly;

3 !ewer active sites available (!or substrate) / "#;

ACCEPT substrate cant access active site

4 (idea o!) more substrate reduces chance o! inhibitor getting in;

ACCEPT more 842 formed in conte$t of overcoming inhibition

" substrate can out9com#ete inhibitor 2 max

[5]

6. (a) (i) 3;4;

5;

:f nd

letter given, no mar 3

(ii) CREDIT answers from clearl! drawn diagrams with bonds

labelled

1 peptide bond;

ACCEPT #e#tide lin

2 between, amine / J group (o! one amino acid) and

carboyl / group (o! another);

3 (!rom amine group) combines with 6 (!rom

carboyl group);

4 condensation reaction

O!

water, lost / eliminated / produced / created / "#;

5 covalent;3 max

Macmillan Academy 4



(b) 1 some 7 groups, attract / repel;

2 disul!ide, bridges / bond;

3 between, cysteine / / (atoms);

4 hydrogen / , bonds; DO NOT CREDIT in conte$t of secondary structure

5 ionic bonds between, oppositely charged / + and , 7 groups;

6 hydrophilic 7 groups, on outside o! molecule / in contact with

water (molecules);

7 hydrophobic 7 groups, on inside o! molecule / shielded !rom water

(molecules);4 max

[10]

7. (i) AWARD 1 mar #er correct row

2om#arative statements must be made in a row

glycogen collagen

1carbohydrate /

polysaccharide

protein / polypeptide ;

2 (alpha) glucose (units) amino acid (units) ;

3 identical units di!!erent amino acid units ;

4 glycosidic, bonds / lin%s peptide, bonds / lin%s ;

5 branched unbranched / linear ;

6 non&helical helical ;

7 one chain (per molecule) three chains (per molecule) ;

8 no cross lin%scross lin%s (between

chains)

;

9 contains - 6 contains - 6 . ;

2 DO NOT CREDIT beta

5 ALLOW straight DO NOT CREDIT strands

! IGNORE S (for collagen)3 max

Macmillan Academy 5



9. 1 untwist / unwind;

DO NOT CREDIT unravel

S 2 unzip / described;

DO NOT CREDIT strands se#arating without 7ualification

S 3 bond brea%s;

4 both strands act as template;

" 5 (aligning o!) !ree (.") nucleotides;

DO NOT CREDIT bases

" 6 complementary, base / nucleotide, pairing;

" 7 - to < and 9 to " / purine to pyrimidine;

" # <o not consider for $WC if mar awarded in the conte$t

of breaing a#art or <5& structure onl!, rather than forming

new double heli$

! 8 hydrogen bonds re!orm;

! 9 sugar&phosphate bac% bone !orms;

! 1# (using) covalent / phosphodiester, bond;

11 semi&conservative replication;

12 ." polymerase;

CREDIT at an! stage in the #rocess

13 "';

e.g. ligase " helicase " g!rase used in correct conte$t

2 – = H bonds " ' – & H bonds

activation of free nucleotides (with #hos#hates)

s!nthesis in the ? to direction

6aai fragments on lagging strand 6 max

QWC & correct se$uence & = S mar%, then = " mar%, then = ! mar%;

:t should be clear that candidate realises that the se7uence is 4,

then 5 then ; 9 even if not written in that order

DO NOT CREDIT if an! ref to transcri#tion " translation1

[7]

1#. (i) polypeptide / protein / primary structure / a se$uence o! amino acids;

DO NOT CREDIT ‘codes for an amino acid

IGNORE en!me " named #rotein1

Macmillan Academy 7



(ii) di!!erent, se$uence o! amino acids / primary structure / "#;

di!!erent protein / protein !olds up di!!erently / di!!erent tertiary structure;

(product) no longer !unctions / di!!erent !unction;

DO NOT CREDIT ‘#roduct or incorrect biochemical (e.g.

carboh!drate)

ACCEPT suitable e$am#le, e.g. active site of en!me no longer

com#limentar! to substrate2 max

[3]

11. double heli;

anti&parallel;

sugar&phosphate;

hydrogen;

[4]

12. (i) percentages / amount, - > < similar (in all organisms);

percentages / amount, " > 9 similar (in all organisms);

di!!erent / named, organisms have di!!erent proportions o!,

bases / named base / "#;

greatest similarity between human and grasshopper;

least similarity between 8 coli and the other three;

8. coli has similar proportions o! all bases /

8.coli has slightly more -< than "9 /(named) eu%aryote has more "9 than -<;

m# 1 @ DO NOT CREDIT ref to a single organism

m# 1 @ IGNORE ref to com#lementar!

DO NOT CREDIT statements in conte$t of organism sie

e.g. statement that human has more & than 8. coli "

human has the most &' " 8. coli has the most 2=

'his mar is for a general statement

comparative !igs with units to support any statement;

e.g. human 2 * 1A.BC and = * 1A.AC

human & * D.AC and 8. coli & * E.-C

‘human has more & (D.AC) than wheat (-.C) * 2

(m# @ -)3 max

Macmillan Academy 8



(ii) (suggests) ", bonds / pairs / lin%s / connects / joins, to 9;

(suggests) -, bonds / pairs / lin%s / connects / joins, to <;

(suggests) purine bonds to pyrimidine;

(evidence !or) complementary base pairing /

which bases pair with each other / base pairing rules;

suggests bases point ?inwards@ rather than ?outwards@;

IGNORE & – ' or & * ' un7ualified

IGNORE 2 – = or 2 * = un7ualified

ACCEPT ‘bond instead of ‘#air 2 max

[5]

13. A%ard & mar' (er correct ro%

feature <5& ;5&

number of

strandstwo / double one / single ;

bases

#resent

thymine / 9

(+ adenine

+ cytosine

+ guanine)

uracil / 8

(+ adenine

+ cytosine

+ guanine)

;

sugar

#resent deoyribose ribose ;

:f a choice of answers is given, do not credit unless bothanswers are valid (e.g. two and double strands for <5& "

ribose and #entose sugar)

ACCEPT letters instead of names of bases

5ames of bases must be unambiguous, so

DO NOT CREDIT adenosine " thiamine " c!steine " etc.

:f more bases mentioned than ' and F, then all bases

must be included

DO NOT CREDIT dio$!ribose " o$!ribose" he$ose " sugar

IGNORE #entose[3]

Macmillan Academy 9



14. carries / trans!ers, the (complementary ."),

code / genetic in!ormation / copy o! gene;

out o! the nucleus;

(trans!ers it) to the, ribosome / 717 / site o! translation;

!or, protein / polypeptide, synthesis;

IGNORE transcri#tion

DO NOT CREDIT ref to the whole <5& code " molecule

ACCEPT ‘to mae #rotein [2]

15. (a) (i) $ hydrogen;

% glycosidic;

DO NOT CREDIT ‘H bond as this is not a name

2orrect s#elling onl!. IGNORE G or or numbers

2

(ii) hydrolysis / addition o! water;1

(iii) A / beta, glucose;

ust be 7ualified as or beta or 3 or b1

(b) enzymes are speci!ic;

the, carbohydrate molecules / substrates,are di!!erent shapes;

active site and substrate are complementary;

so that substrate will !it / !ormation o! 1-;

loc% and %ey / induced !it;3 max

Macmillan Academy 10



E using, a blan% / water / unreacted *enedicts;

F use (red) !ilter;

=G reading o!, transmission / absorbance;

== more transmission / less absorbance, o! !iltrateH more sugar present; ,'a

=2 (obtain) calibration curve;

=: plotting, transmission / absorbance,

against (reducing) sugar concentration;

=B use reading o! un%nown sugar solution and read o!! graph

to !ind concI;

e.g. serial dilutions

ALLOW boil " > BDo

2 DO NOT CREDIT warm DO NOT CREDIT amount " 7uantit!

CREDIT descri#tion of method

e.g. filtering " centrifuging @ decanting

&228' ‘measure how much light, does " does not,

#ass through

:f #reci#itate is clearly indicated as being #resent in

sam#le, ALLOW ‘less transmission " more absorbance,

* more sugar #resent [6]

17. brea%ing (glycosidic) bond; ! i! incorrect named bond

glycosidic / correct bond drawn; treat ?covalent@ H neutral

addition o! water / 26; ma 2

[2]




18. acce#t * !es * no

each correct row * : mar

gum arabic amylase cellulose glycogen

branched structure no; yes;

heteropolysaccharide no; no;

!ound in

animals/plants

plants; animals;

!unction in organismstorage / reserve;

! ?energy@ alone

structural / strength

/ stops bursting /

cell wall / support /

gives cell shape;

! protects rigid H

neutral

[4]

19. (i) crush (small amount o!) seed pod;

add (small volume o!) biuret, " / .a6, and biuret, * / -u6B;

positive H colour change !rom blue to, mauve/purple; ma 2

(ii) #re#aration 9 allow mars ma$%

= crush, samples / leaves and seed pods, separately with water;

2 use same mass o! each / "# and use same volume o! water;

: !ilter;

method 9 allow E mars ma$%

B add benedict@s reagent to !iltrate; $ -u6B in al%aline solution

C ecess reagent used / stated volume;

same volume added;

D heat in a water bath/ at near boiling;

E !or stated time (up to C min);

anal!sis 9 allow mars ma$%

either

F colour change !rom blue to green / yellow / orange / red;

=G shows increasing concentration o! reducing sugar;

or

== use o! centri!uge to remove precipitate;

=2 use o! colorimeter to compare intensity o! blue colour in

li$uid portion;

=: red !ilter used in colorimeter; E




(b) assume candidates are referring to the initial rate unless otherwise stated.

concentration o!, substrate / 262, molecules, high / higher at start;

more chance o!, substrate/ 262, molecules entering active site;

all / most, active sites occupied; :

[5]

23. at o#timum tem# 9 ma$ mars

molecules in culture have %inetic energy;

(!re$uent) collisions between enzyme and substrate molecules;

more enzyme&substrate complees !ormed;

ma rate o! reaction / protein production achieved;

at higher tem# 9 ma$ ? mars

(at higher temperature) molecules have more %inetic energy /

collisions occur more !re$uently and with more energy;molecules vibrate and, bonds/ hydrogen bonds, bro%en;

tertiary structure / : shape, o! enzymes altered;

active site loses, precise / complementary, shape;

enzymes are denatured;

substate molecule no longer !its active site;

(may be) irreversible so reaction/ protein production stops; $ !ungus destroyed[8]

24. (a) (i) ar the first t!#es of biological molecule stated. &bsence * neutral protein; $ casein/polypeptide ! amino acid

reducing sugar(s); $ correctl! named reducing sugar(s)

Kbut onl! lactose"galactose"glucoseL 2

(ii) ar the first t!#es of biological molecule stated. &bsence * neutral

protein; $ casein"#ol!#e#tide ! amino acid

reducing sugar(s); $ correctl! named reducing sugar(s)

Kbut onl! lactose"galactose"glucose"fructoseL

non&reducing sugar; $ sucrose :

(b) &ssume ‘it * ‘Health9il

‘Health – il has

less reducing sugar(s); $ correctl! named reducing sugar(s)

Kbut onl! lactose"galactose"glucose"fructoseL

less non&reducing sugar; $ sucrose

Mless sugarN * 1

credit converse statements relating to ‘8nerg! – 3oost. 2




(c) states ?no added sugar@/implies low sugar;

contains more sugar than (!resh) mil%/high in sugar;

more reducing sugar (than mil%); ! ‘none in fresh mil

has non&reducing sugar (compared to none in mil%);

!ruit (etract) must contain (hidden) sugar; : ma

(d) mil%/drin%s, already,

mil%y/cloudy/white/opa$ue/?not see through@/emulsion;

$ ‘#ositive result would not show u# ! #reci#itate =[11]

25. (i) ! statements lined to am!lose"starch

ma$ if stated that gl!cogen is am!lo#ectin

polymer/polysaccharide/described;

(made o!) K&glucose;

joined by =,B lin%s;

glycosidic;

(chain is) branched;

=, lin%s where branches attach;

"'; eIgI compact

detail o! glycosidic bond B ma

(ii) condensation; $ #ol!merisation =

[5]

26. (i) :D L-; $ an! figure in the range ? – ED =

(ii) (enzyme) increases in %inetic energy; $ ) too much inetic energ!

enzyme vibrates too much;

brea%s bonds;

named eg;

changes, tertiary/:&, structure/shape, o! enzyme;

active site changes, shape/"#;

substrate will not !it/no enzyme&substrate comple !ormed;enzyme denatured;

will, decrease rate/stop reaction; B ma[5]




27. 1 mar #er correct row

/oo for both tics and crosses.

:f a table consists of tics 65/O or crosses 65/O, then assume that the blan s#aces are the

other s!mbol.

:f a table consists of tics, crosses and blans then the blans re#resent no attem#t at the

answer.

.ucleotides line up along an eposed ." strandI ;

9he whole o! the double heli ?unzips@I ;

8racil pairs with adenineI ;

" t7." triplet pairs with an eposed codonI ;

*oth ." polynucleotide chains act as templatesI ;

"djacent nucleotides bond, !orming a sugar&phosphate bac%boneI ;

9he original ." molecule is unchanged a!ter the processI ;

"denine pairs with thymineI ;[8]

28. hydrolysis (o! b);

by enzymes;

proteases;

brea%s peptide bonds;

removal o! haem group;

re!erence to, di!!usion/active transport/pinocytosis/channel proteins;

"'; : ma[3]




29. ,ne ma'( ,' each c,''ec- ',

) ,n0 -)c(s assme -ha- s+aces a'e c',sses; ) ,n0 c',sses

assme -ha- s+aces a'e -)c(s

; h/')d -)c(s

statement

substance*se

heat

use

biuret

reagent

use

3enedicts

reagent

boil

with a

dilute

acid

a

#ositive

result is

a blue9

blac

colour

a #ositive

result is

an

emulsion

li#id

#rotein ;

starch ;

reducing

sugar ;

non9

reducing

sugar

;

B[4]

3#. (i) glycosidic; $ covalent / -&6&- / oygen bridge

! oygen bond / ?glucosidic@ =

(ii) hydrolysis / hydrolytic; if 7ualified, needs to be correct =[2]

31. 1 no (suitable) enzyme (in gut) to digest sucralose /

sucrase will not act on sucralose / "#;

2 enzymes, are speci!ic / only act on one substrate;

3 complementary shape;

4 idea that (2" on sucralose instead o! 6) gives di!!erent, shape / structure;

5 no 1- (enzyme substrate comple) / substrate will not !it into

active site;

6 "'; eIgI !urther detail o! enzyme&substrate interaction B ma[4]




32. = hydrogen bonding;

2 detail; eIgI (electro)negative oygen atom can hydrogen bond to

(electro)positive atom/ one water molecule hydrogen bonds with

up to B others / bonds individually wea% / large collective e!!ect

o! many hydrogen bonds

coral algae

: (high) thermal stability / temperature remains !airly constant;

B water has high speci!ic heat capacity;

C much energy needed to brea% hydrogen bonds;

#olar bears

cooling allows maimum number o! hydrogen bonds to !orm;

D water molecules space out to allow this;

E water epands as it !reezes / ice is less dense than water;

mussels, filter9feeders and sessile animals

F water is transport medium !or, !ood particles / gametes;

=G (tentacles / appendages / cilia) create currents bringing !ood;

== re!I tides / ocean currents;

=2 medium !or, male gametes to swim / eternal !ertilisation;

=: no desiccation o! gametes;

=B re! to low viscosity / "#;

corals

=C minerals / ions, are soluble in water;

= water is polar / detail o! electrostatic attraction; $ "#

seaweeds, fish e!es=D water is transparent to light;

=E photosynthesis possible (in shallow water);

=F wavelength o! light varies with depth;

whales, Iell!fish

2G cohesion / water molecules stic% to each other;

2= water not easily compressed;

22 gives support to large bodies / detail o! upthrust or relative density;

2: acts as hydrostatic s%eleton;

2B "'; eIgI zonation / pigments

2C "'; eIgI solubility o! named gas lin%ed to use in named organism D ma

QWC 0e*)/0e -ex- )-h acc'a-e s+e00)n* +nc-a-),n and *'amma' =[8]




33. (i) not enough points plotted / eperiment not carried out at

enough (di!!erent) p values;

only = point between : + BI: / no points between :I2C + BI:;

don@t %now / uncertainty o!, rate between those points /

where pea% should be / where optimum is;

:I2C reading might be anomalous;cannot draw, curve / line o! best !it;

rises to, : / :I2C, and !alls a!ter BI:; 2 ma

(ii) note P en!me is com#letel! inactive at #H -

loss o! tertiary structure / loss o! : structure / (enzyme) denatured;

(change in p/M+N) alters charge distribution on (enzyme) molecule;

hydrogen / ionic, bonds a!!ected;

changes (shape o!) active site;

enzyme substrate comple cannot be !ormed /

substrate not attracted to active site /substrate cannot bind to active site / "#; 2 ma

[4]

34. mar each section (8, 4 and 2) to ma$ shown

en+yme concentration ,

1 reaction (rate) increases with increased enzyme; $ high / low

2 more active sites available;

3 in ecess substrate / as long as enough substrate (molecules

available to occupy active site);

4 (as reaction progresses) the rate will decrease as substrate,

used up / becomes limiting; ! plateau

(: ma)

S s*-strate concentration ,

1 reaction (rate) increases with increased substrate; $ high / low

2 more, molecules available to enter active site / 1- !ormed;

$ more success!ul collisions

3 reaches point where all active sites occupied;

4 no !urther increase in rate / reaches ma; $ plateau / levels o!!

5 enzyme concI becomes limiting / unless add more enzyme; S

(: ma)




C com(etiti.e inhi-itor ,

1 inhibitor has similar shape to substrate;

2 can, !it / occupy, active site;

3 !or short time / temporary / reversible;4 prevents / bloc%s, substrate !rom entering active site;

5 rate determined by relative concentrations;

6 little inhibition / rate little reduced, i! substrate concI O inhibitor concI; ora

7 re! to chance o!, substrate / inhibitor, entering active site;

8 e!!ects can be reversed by increasing substrate concI; C

(C ma)

/eneral (oints ,

1# drawing a suitable graph to illustrate point made with labelled aes;

11 re! to optimum (rate); F ma

QWC 0e*)/0e -ex- )-h acc'a-e +nc-a-),n s+e00)n* and *'amma' =[10]

35. (a) protein / polypeptide, with,

carbohydrate (chain) / polysaccharide / sugar / glucose;

R /lyco/en =

(b) (i) (K) heli; ! double heli =

(ii) (A) pleat(ed) (sheet); =

(c) tertiary / :L; =[4]

36. solvent;

li$uid; $ same

dense;

insulates; $ %eeps warm ! protects / warms

hydrogen; $ / wea% ! + / 2

sur!ace tension / cohesion; [6]




37. cholesterol not soluble (in water) ;

lipids / cholesterol, hydrophobic / non&polar ;

glucose is (very) soluble (in water) ;

glucose is, hydrophilic / polar ; 2 ma[2]

38. $ correct formulae

! choice (if contradictor!)

t!#e of molecule

tested reagents used #ositive result negative result

#rotein

biuret / copper sulphate

and

sodium (or potassium)hydroide;

purple / mauve /

lilac;

blue solution

!at / lipid / oil /

triglyceride;

$ #hos#holi#id

alcohol and water white emulsion clear li7uid

starch

iodine

(in potassium iodide

solution);

blue&blac% /

blac%; !ellow solution

[5]

39. (i) ! references to fruit Iuice

use same volume o! glucose solution;

use same volume o! *enedict@s solution;

use same concentration o! *enedict@s solution; $ strength " same batch

boil !or the same length o! time; $ heat

calibrate colorimeter / "#; $ same, filter " colorimeter 2 ma

(ii) IC; =

(iii) hydrolyse !iltrate / juice / bond / non&reducing sugar;either

with acid, neutralise / add al%ali

or

treat with sucrase / invertase;

either, if started with filtrate Q

boil with *enedict@s + test !iltrate / repeat original procedure; $ heat

or, if started with Iuice Q

boil with *enedict@s + test !iltrate / repeat original procedure to

measure di!!erence in absorbance with original; 2 ma[5]




4#. (i) haemoglobin / haem; ! Hb =

(ii) iron / Pe2+

/ Pe:+

; ! ion " Re " Re+

=[2]

41. (i) brea%ing a bond with the addition o! water; $ named bond =

(ii) !atty (acids produced);

M+N increased / more acidic / products are acidic / acids produced;

?!atty acids produced@ H 2 mar%s 2

(iii) do not credit, substrate used u# " lac of en!me " end #roduct inhibition

p too low / not optimum; $ too acidic

enzyme denatured;

e$uilibrium reached;

!urther detail; 2 ma[5]

42. reduces rate; $ sto#s ! inhibits

!its into allosteric site / site other than active site;

$ ? fits into active site #ermanentl!

alters shape / charge o! active site;

so substrate cannot !it to active site / bind to active site / !orm 1-;

will not reach ma;

increasing substrate concentration has no e!!ect (on the rate); : ma[3]

43. (a) ! first reference to1? 5 being radioactive

semi9conservative re#lication would give

1 one, template / original / old / parent strand and one,

new / daughter strand;

2 complementary base pairing / joining o! new nucleotides /

other detail o! !orming the new strand;

data shows that

3 two isotopes in molecule / molecule contains both=B . and

=C .;

4 one strand with ?heavy@ . /=C .; ! molecule

5 one strand with ?light@ . /=B .; ! molecule

6 no molecules with only = isotope /=B . /

=C .;

some #oints, #articularl! E and ?, could be awarded for a

correctl! labelled or e!ed diagram B ma




(b) correct answer onl! 9 do not acce#t from a selection

";

-;

- and 1; :

(c) 1 band * D

bands * D

band drawn !or=B . and

=B ./

=C . only;

thic% !or=B . and thin !or

=B ./

=C .; 2

[9]

44. a!ter a low carbohydrate diet athlete can eercise !or, not long /

(no more than) one hour; $W orastatement o! trend observed; eIgI as carbohydrate in diet increases duration o!

eercise increases / carbohydrate loading improves per!ormance; $W ora

use o! !igures as a comparison; (loo% !or G, =2C =:G, and =EC =FG)

$ two / three, times duration statements : ma[3]

45. #enalise sugar once in the answer

glycogen is, source / store, o!, energy / carbohydrate;

glycogen converted to glucose / glycogenolysis / glucogenesis;glucose used in respiration;

to supply, energy / "9', !or muscle contraction;

more glycogen stored will last longer;

"'; eIgI using muscle glycogen may be more e!!icient than

transporting glucose !rom liver 2 ma[2]




46. (i) polypeptide; $ oligopeptide =

(ii) glycine; $ proline / alanine =

(iii) in this answer assume that

chain * #ol!#e#tide

molecule * grou#s of #ol!#e#tide chains

$ ecf for named amino acid from (ii) but 56' a name of a base

amino acids / glycine, small (to allow close pac%ing);

the small one is, every :rd

amino acid / at every level in the molecule;

chains, !orm a tight coil / lie close to each other;

held together by hydrogen bonds; ignore other bonds

bonds !orm between 7 groups o! lysines;

molecules !orm, !ibres / bonds with adjacent molecules; $ !ibril

covalent bond between, adjacent molecules / -6&. groups;

!ibres composed o! parallel molecules;

ends o! parallel molecules staggered; prevents line o! wea%ness; 2 ma[4]

47. cell wall(s);

β / beta; $ *

glycosidic; "O: glucosidic

=EG;

straight; $ polysaccharide / unbranched / linear

hydrogen / ; "O: 2

[6]

48. (i) B; =

(ii) deoyribose; "O: ribose

phosphate;

nitrogen(ous) / organic / named, base; $ purine / pyrimidine

"O: uracil

"O: letter

"O: thiamine / thyamine

ta%e a correct base !rom a list unless that list includes uracil :[4]




49. 1 2, molecules / helices, (o! .") produced;

2 identical (molecules o! ." produced);

3 (each made up o!) =, original / parent / old, strand;

4 = new strand;5 original / parent / old, strands, act as template / described;

6 re! to (!ree .") nucleotides; : ma[3]

5#. (a) idea that arachidonate is substrate;

phospholipid source in membrane;

prostaglandin / product, can be, transported / stored;

()17 !or, lipid / steroid, synthesis / transport;

"';"'; eIgI separate !rom other reactions

cytoplasm environment not suitable !or, reaction / enzyme ora

idea that prostaglandin isolated

-6 does not, damage / use phospholipids !rom,

other membranes 2 ma

(b) ibu#rofen

competitive;

ibupro!en bloc%s / arachidonate cannot enter, channel; $ substrate

cannot reach active site;

as#irin

non&competitive;

changes shape (o!) / bloc%s;

active site;

"'; eIgI allosteric

no 1- !ormed / "#; allow once onl! B ma

(c) $ reverse argument as long as 7uestion is answered in terms

of low tem#erature

slows, reaction / rate / activity o! enzyme / "#;re! %inetic energy;

molecules moving, slowly / less;

!ew collisions / collisions less li%ely;

!ew 1- !ormed / 1- less li%ely to be !ormed;

reversible / enzyme not denatured / enzyme still wor%s;

re! activation energy;

re! Q=G H 2; B ma

[10]




51. similar P allow valid similarities such as

same number, carbon / oygen / hydrogen (atoms) / 6 (groups); $ heose

same !ormula; ! similar / molecule

ring / ring with 6 (atom) in it;

correct re! -26;contain -, and 6; = ma

different P assume candidate is writing about fructose unless told otherwise

allow valid differences such as

(!ructose has) C&membered ring / glucose has &membered ring; ! pentose

(E 2 in ring v. ?2 in ring " furanose v. #!ranose in glucose)

(in !ructose) 2 -26 side chains / = -26 side chain in glucose;

di!!erent angles between - atoms;

re! alignment o! and 6 groups (on carbon : / carbon B);

(in !ructose) carbon = not in ring / carbon = in ring in glucose; = ma[2]

52. (i) glycosidic; "O: glucosidic =

(ii) 1 carbon positions = and 2 on glucose and !ructose;

2 !ormation o!, water / 26, !rom 2 6 groups (plus separation);

3 oygen bridge / 6 , shown; 2 ma[3]

53. (i) add / use, *enedict@s (reagent);

heat; "O: use water bath alone

(blue to) green / yellow / orange / brown / red (precipitate); :

(ii) hydrolysis;

boil / heat, with (dilute), acid / -l; $ (dil) .a6

(add) hydrolytic enzyme / sucrase / invertase; = ma[4]

54. (a) active site correctly labelled; =

(b) C; =

(c) shape o! active site;

complementary;

correct shape / correct molecule / correct substrate / C, will, !it /

!orm 1-;

any other shape / any other molecule / any other substrate /

$ / % / ; / , will not;

award mars if candidate writes ‘onl! correct Q.. ) : ma

(d) loo for #oints relating to the substrate changing sha#e




ignore refs to en!me changing sha#e

puts strain on the bonds in the substrate / bonds brea% more easily;

$ wea%ens bonds

lowers activation energy;

"'; eIgI re!erring to anabolic reaction = ma[6]

55. enzymes (o! microorganisms) wor% in low temperatures;

enzymes used in stain removal / "#;

can be used !or cool washes;

saves energy; 2 ma[2]

56. maring #oints 1, E, B, 1E, 1A, D and relate to the bullet #oints in the 7uestion

1 li$uid at normal temperatures;

2 hydrogen bonding between water molecules;

3 molecules more di!!icult to separate;

4 ice !loats on water / water !reezes !rom top down;

5 insulates water beneath;

6 large bodies o! water don@t !reeze completely / animals can still swim etcI;

7 (change in density with temperature) causes currents to circulate nutrients;

8 solvent !or, polar / ionic, substances;

9 solubility o! gases in environment;

1# allows reactions to ta%e place;11 transport medium;

12 eIgI (o! substance carried in what);

13 transport medium !or, gametes / blood cells;




14 water slow to change temperature;

15 la%es / oceans / large volumes, provide thermally stable environment;

16 internal body temperature changes minimised;

17 used !or cooling;

18 eIgI (sweating / panting / transpiration);

19 large amount o! energy must be removed !or water to !reeze;

2# organisms can use sur!ace o! water (as habitat);

21 eIgI; (o! organism)

22 can !orm (long / unbro%en) columns o! water;

23 re!I to vascular tissue / ylem;

24 reactant (photosynthesis);

25 role in, hydrolysis / condensation;

26 "'; eIgI transparency

27 "'; plants can photosynthesise under water

incompressible

hydrostatic s%eleton / turgor

buoyancy

guard cell mechanism

support !or large organisms on ice (penguins / polar bears)

!urther detail o! any point F ma

QWC 0e*)/0e -ex- )-h acc'a-e s+e00)n*, +nc-a-),n and *'amma'; =[10]

57. deoyribose in .";

thymine in ."; ! thiamine

." is, made o! two chains / double heli; ! double molecule

longer; 2 ma[2]

58. (i) answer has to relate to <5& nucleotide

monomer unit;

deoyribose;

nitrogenous base / named base(s); ec! !or thiamine

phosphate;

"'; eIgI deoyribose is a pentose sugar / correct diagram : ma

(ii) hydrogen bonds between bases;

complementary (base pairs);

purine to pyrimidine;

" to 9 and - to <;

2 bonds between " and 9 / : bonds between - and <;

." polymerase; : ma[6]




59. ." codes !or, protein / polypeptide;

transcription and translation (or described);

enzyme is globular (protein);

: bases ≡ = amino acid;

se$uence o! bases / triplets, determines, se$uence o! amino acids /

primary structure;

coiling / α heli / β&pleated sheet / particular secondary structure;

determines projecting side groups;

!olding / bonding, !or tertiary structure;

:& structure is tertiary structure;

"'; eIgI re!I active site related to shape

2 or more genes produce $uaternary structure B ma[4]

6#. (i) loo for #roar!ote feature

no nucleus / no nuclear membrane / no nucleolus / ." !ree(in cytoplasm); ! ." moving

na%ed ." / ." not associated with proteins / no chromosomes;

circular / loop, .";

no, membrane&bound organelles / eIgI;

smaller / =Enm / DG, ribosomes;

no 17;

cell wall, not cellulose / polysaccharide and, amino acids / murein;

"'; eIgI mesosomes / plasmids = ma

(ii) glycosidic (lin%) and peptide (bonds) (in correct contet);

condensation;re!I 6 groups;

re!I .2 and 6 group;

water, removed / produced / by&product;

enzyme;

"'; eIgI energy re$uired : ma

(iii) iron / Pe; ignore #luses " minuses =

(iv) treat en!me as neutral

nitrogenase;

leghaemoglobin;haemoglobin; 2 ma

(v) (nitrogen) !iation; $ reduction =

(vi) type o! inhibition (competitive / non&competitive / reversible / irreversible);

basic mode o! action (eIgI binds to active site);

detail;

conse$uence (eIgI prevents, substrate / nitrogen, !rom binding); 2 ma[10]

61. active site; =




[1]

62. activation (energy); =[1]

63. gene / allele; $ cistron ! genes / alleles / operon / intron =[1]

64. (a) (i) add / mi with, alcohol / ethanol / propanone / (suitable)

organic solvent;

then, add to / add / mi with, water;

water alone * D

! heat 2

(ii) emulsion / mil%y colour / cloudy / "#; ! precipitate =

(b) #hos#holi#ids have

= less !atty acid (residue) / 2 !atty acid (residues) not :; $ hydrocarbon

= less ester bond / 2 ester bonds not :;

phosphate;

choline / base / nitrogen;

hydrophilic / polar, end / head; ma :

(c) (i) add, copper sulphate (solution) and sodium hydroide (solution) /

biuret (reagent);

! *iuret test un$uali!ied

! heat =

(ii) purple / mauve / lilac; ! blue =[8]




65. #rimar!

se$uence / order, o! amino acids (in a polypeptide); $ 7 groups =

secondar!

coiling / !olding, o! the,

polypeptide / chain o! amino acids / peptide chain / primary structure;(α&) heli;

(β&) pleated sheet;

hydrogen bonds;

between amino acids in (same) chain;

(between) . and -6;

"'; eIgI random coiling ma B[max 5]

66. (a) (malonate) same / similar, shape as, succinate / substrate;

$ idea that inhibitor is complementary to active site binds to / !its / bloc%s, active site;

!or a limited time / reversible / may leave / "#;

! does not bind permanently

prevents, !ormation o! 1- / substrate !rom binding; "#

no / less, product !ormed; $ suitable re!I to conversion o! succinate ma :

(b) rate increased;

greater chance o! substrate binding with, active site / enzyme; ora

more, product !ormed / substrate converted;

will reach ma / rate una!!ected, i! great ecess o! succinate;

"'; eIgI graph o! rate against substrate concentration

e!!ect o! time (using up substrate) ma :[6]

Every Biological Molecules Answer

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