1.	C
[1]

2.	B
[1]

3.	D
[1]

4.	C
[1]

5.	D
[1]

6.	C
[1]

7.	C
[1]

8.	A
[1]

9.	D
[1]

10.	(a)	(i)	(population) 1 and (population) 2 (both needed)	1
 
(ii)	(population) 11/7/7 and 11	1
 
(b)	PanIA 0.75 and PanIB 0.25 / 3 PanIA to 1 PanIB	1
Both must be correct for the mark to be awarded, accept
frequencies in form of ratio.
 
(c)	(i)	greatest/great frequencies of PanIA at lowest/low latitudes /
a rapid drop in frequency at (60–65 degrees latitude) /
lowest/low frequencies at highest/high latitudes	1
Answers which describe/imply the correct step-wise relationship
should get credit. Answers stating or implying a negative
correlation alone should not get credit.
 
(ii)	lowest/low frequencies of PanIA at lowest/low temperatures /
a rapid increase in frequency at (8–10 degrees Celsius) /
highest/high frequencies at warmest/warm temperatures	1
Answers which describe/imply the correct step-wise relationship
should get credit. Answers stating or implying a negative
correlation alone should not get credit.
 
(d)	(cod with) PanIA allele selected/favoured/better adapted to warmer water;
(cod with) PanIB allele selected/favoured/better adapted to colder water;
cod that survive can reproduce and pass alleles on to offspring;	2 max
It takes a whole organism to reproduce in order to pass on the allele,
hence we expect reference to the fish to gain this last marking point.
 
(e)	higher frequency of PanIA/PanIA PanIA (cod) in warm (surface) water;
higher frequency of PanIB/PanIB PanIB (cod) in colder (deeper) water;
interbreeding results in PanIA PanIB cod/heterozygous cod;	2 max
 
(f)	PanIA PanIA (cod) may spread further north / PanIB PanIB (cod)
may move/retreat further north;
numbers of PanIA PanIA (cod) may increase / frequency of PanIA
allele may increase;
PanIB PanIB (cod) may become extinct / frequency of PanIB allele
may decrease;	2 max
[11]

11.	(a)	cell wall protects the cell from damage;
cell wall prevents the cell from bursting;
plasma membrane pumps substances/carries out active transport;
plasma membrane controls entry and exit of substances;
cytoplasm contains enzymes that carry out metabolism;
pili are used to connect bacterial cells/can pull bacteria closer together;
flagella used for locomotion/movement of the bacterial cell;
ribosomes synthesize proteins;
(naked) DNA of main chromosome is located in the nucleoid (region);
nucleoid initiates reproduction/binary fission;
(naked) DNA/chromosome/nucleoid controls/determines cell
structure/function;
plasmids confer (luxury) functions such as disease resistance/
antibiotic resistance/other;
capsule protects cell/promotes adherence;	9 max
If the answer includes any eukaryotic structures, award [8 max].
 
(b)	both lipids and carbohydrates are primary sources of energy for
organisms;
lipids store more energy per unit mass/per gram than carbohydrates /
lipids generally provide 2 to 3 times the energy of carbohydrates
for a given mass;
lipids provide 38 kJ g–1/9 C g–1 whereas carbohydrates have
17 kJ g–1/4 C g–1;
carbohydrates are easier to transport (than lipids) making their
energy more accessible;
because lipids are insoluble (in water) whereas (small)
carbohydrates are soluble (in water);
carbohydrates are more easily taken out of storage making their
energy more quickly available;
carbohydrates are short-term storage molecules, whereas lipids
provide long-term storage;	4 max
 
(c)	aerobic cell respiration if oxygen available and anaerobic if
unavailable;
pyruvate enters mitochondrion for aerobic respiration;
whereas pyruvate stays in the cytoplasm for processing under
anaerobic conditions;
pyruvate converted aerobically into carbon dioxide and water;
whereas pyruvate converted anaerobically to lactate;
large ATP yield when oxygen available/from aerobic cell
respiration;
no (further) ATP yield without oxygen;	5 max
(Plus up to [2] for quality)
[20]

12.	(a)	rough endoplasmic reticulum/RER/rough ER / ribosome	1
 
(b)	vesicles are formed (from the rough ER);
they are received by Golgi apparatus;
Golgi apparatus forms vesicles that transport substances to membrane;	2 max
 
(c)	aerobic respiration takes place in the mitochondria;
important for energy/ATP production;
pyruvate broken down into carbon dioxide and water;	2 max
 
(d)	they are cut in different planes / due to three-dimensional nature/shape	1
[6]

13.	D
[1]

14.	D
[1]

15.	C
[1]

16.	A
[1]

17.	D
[1]

18.	(a)	(i)	interphase because no (individual) chromosomes are visible /
genetic material visible as chromatin / chromosomes/DNA
has not condensed /nuclear envelope/nucleolus/nucleus is visible	1

(ii)	DNA synthesis/replication/OWTTE;
(cell) growth / increase in the number of organelles/specific
organelle mentioned;
transcription/synthesis of RNA;	2 max
Mark only the first process on each line if more than two
processes are listed. Do not accept error carried forward
if mitosis is the answer in (i).
 
(b)	retain the capacity to divide;
they are undifferentiated / unspecialized;
have the ability to differentiate (along different pathways) / are multipotent/pluripotent/totipotent;	2 max
Mark only the first process on each line if more than two processes
are listed.
 
(c)	named source of stem cells e.g. bone marrow / cord blood / inner
cell mass of embryo / embryonic stem cells;
name of condition that is treated using the stem cells e.g. leukaemia /
heart disease / diabetes / other possibility;
one precise detail of how the stem cells replace/replenish
(differentiated) cells that are the cause of the condition;	3
	Example:
Source: stem cells obtained from bone marrow;
Condition: leukaemia;
Detail: patient’s bone marrow cells (are killed and) replaced with
the stem cells;
[8]

19.	A
[1]

20.	D
[1]

21.	A
[1]

22.	B
[1]

23.	D
[1]

24.	B
[1]

25.	A
[1]

26.	B
[1]

27.	B
[1]

28.	B
[1]

29.	(a)	two genetically identical nuclei/daughter cells formed during mitosis
(so hereditary information in DNA can be passed on);
two copies of each chromosome/DNA molecule/chromatid needed;
helicase unwinds the DNA/double helix;
to allow the strands to be separated;
helicase separates the two (complementary) strands of DNA;
by breaking hydrogen bonds between bases;	4 max
 
(b)	DNA replication is semi-conservative;
DNA is split into two single/template strands;
nucleotides are assembled on/attached to each single/template strand;
by complementary base pairing;
adenine with thymine and cytosine with guanine / A with T and C with G;
strand newly formed on each template strand is identical to other
template strand;
DNA polymerase used;
Marks may be awarded for any of the above points if clearly presented in
a well-annotated diagram.	5 max

(c)	sequence of stages is prophase → metaphase → anaphase → telophase;
chromosomes condense/supercoil/become shorter and fatter in prophase;
spindle microtubules grow (from poles to equator) in prophase/metaphase;
nuclear membrane breaks down in prophase/metaphase;
spindle microtubules attach to the centromeres/chromosomes in metaphase;
chromosomes line up at equator in metaphase;
centromeres divide / (paired) chromatids separate / chromosomes
separate into two chromatids in metaphase/anaphase;
(sister) chromatids/chromosomes pulled to opposite poles in anaphase;
spindle microtubules disappear in telophase;
nuclear membrane reforms around chromosomes/chromatids in telophase;
chromosomes/chromatids decondense in telophase;	9 max
	(Plus up to [2] for quality)
[20]

30.	(a)	At least one characteristic from each group is needed for maximum
credit.
bryophyta have no roots / only have rhizoids;
bryophyta have simple leaves/stems / only a thallus;
bryophyta produce spores in capsule;
byrophyta are nonvascular;
bryophyte exhibit (pronounced) alternation of generations / a
significant gametophyte generation;
	filicinophyta have roots, stems and leaves;
filicinophyta (often) have divided/pinnate leaves;
filicinophyta produce spores in sporangia/spores on the undersides of leaves;
filicinophyta exhibit alternation of generations;
filicinophyta have primitive vascular tissue / no true xylem and phloem;
	coniferophyta have woody stems;
coniferophyta (often) have narrow leaves/needles/scales;
coniferophyta produce seeds in cones/unenclosed seeds;
	angiospermophyta have flowers;
angiospermophyta have ovules in ovaries;
angiospermophyta produce seeds (with hard coats) in fruits;	9 max
 
(b)	starch is a large molecule;
large molecules/starch cannot be absorbed by the intestine/villi/epithelial
cells;
glucose produced by digestion of starch can be absorbed;
starch/glucose is a useful source of energy;
starch is not used in humans;
glucose is stored as glycogen not starch;
starch is not soluble/could not be transported by blood;	4 max

(c)	In the table below, information from both boxes on same line is
needed for 1 mark.
Differences [4 max]:
Prokaryotic cells	Eukaryotic cells	
no nucleus	nucleus;	
naked DNA	DNA associated with histone/protein;	
loop of DNA	strands of DNA;	
no mitochondria	mitochondria;	
70S/ smaller ribosomes	80S/ larger ribosomes;	
no/few internal membranes / no organelles	internal membranes/organelles/ Golgi/ER/lysosomes;	
smaller in size (approx. 1-10µm)	larger in size (approx. 10-100µm);	
cell wall (glycoprotein) present	sometimes present/not in animal cells;	
	Similarities: Award 1 mark for any combination of two different
items [2 max].
cytoplasm/plasma membrane/contains DNA/contains ribosomes	5 max
	(Plus up to [2] for quality)
[20]

31.	(a)	hydrogen bonds between nucleotides of opposite strands/complementary
bases/adenine and thymine and cytosine and guanine;
covalent bonds between nucleotides within strands/between
sugar/deoxyribose and phosphate;	2
 
(b)	hydrogen bonding between water molecules;
breaking (hydrogen bonds) needs/removes energy/heat;
hydrogen bonds must break when water evaporates/vaporizes;	2 max
 
(c)	osmosis / moves passively;
from regions of low solute/high water potential/concentration to
high solute concentration / low water potential/concentration;
passes through protein channels/aquaporins/selectively-permeable
membrane;	2 max
 
(d)	water molecules undergo photolysis/are split by light energy;
forms oxygen as a by-product;
hydrogen helps power the fixation of carbon (into organic molecules);	2 max
[8]

32.	(a)	Award [1] for each linked set of answers.
simple diffusion	facilitated diffusion	
energy requirement	none	none;	
direction of movement	down concentration gradient	down concentration gradient;	
specificity	not specific	specific;	
passage directly through phospholipid membrane	yes	no;	
protein channels	not required	required;	
solute	simple molecules / O2 / CO2	sugars/amino acids;	
solute binding to carriers	no	yes;	
speed of diffusion	slower	faster;	
		5 max
 
(b)	endocytosis occurs when a membrane encloses a target particle;
fluidity of membrane permits movement of membrane;
membrane sinks inwardly/forms pit/invaginates to enclose particle;
membrane seals back on itself / edges fuse;
one membrane layer / two phospholipid layers enclose particle making
vesicle;
inner phospholipid layer of (original) membrane becomes outer
phospholipid layer of vesicle membrane;
outer phospholipid layer of (original) membrane becomes inner
phospholipid layer of vesicle membrane;
vesicle breaks away from membrane/moves into cytoplasm;
changes in membrane shape require energy;
specific example of endocytosis (e.g. pinocytosis, phagocytosis);
Accept any of the above points in an annotated diagram.	5 max

(c)	resting membrane is polarized;
interior is –70 mV/negative relative to outside;
more sodium ions outside than inside;
more potassium ions inside than outside;
disturbance of membrane opens sodium ion channels;
sodium ions rush to inside of cell;
causing depolarization;
sodium ion channels shut;
potassium ion channels open;
potassium ions rush out;
helping to restore polarized state of membrane;
sodium–potassium pumps maintain polarity;
process repeated along the length of neuron / sodium ions diffuse between
region with an action potential and the region at resting potential;	8 max
	(Plus up to [2] for quality)
[20]

33.	D
[1]

34.	C
[1]

35.	(a)	name of component [1 max] e.g. plant cell wall/cellulose/interstitial matrix/
basement membrane/glycoprotein/bone matrix;
	functions [3 max]
EITHER
e.g. (plant cell wall) strengthens/supports the cell/plant (against gravity);
prevents the entry of pathogens;
maintains the shape of plant cells;
allows turgor pressure/high pressure to develop inside the cell;
prevents excessive entry of water to the cell;
	OR
helps cells to stick together/adhere;
needed to hold cells/tissues together / example of cells/tissues
holding together;
forms interstitial matrix / forms basement membrane to support single
layers of cells;
e.g. around a blood capillary;
forms (part of the) filtration membrane in the glomerulus;	4 max

(b)	vesicles carry material to plasma membrane;
vesicle fuses with membrane;
(by joining of) phospholipid bilayers;
aided by the fluidity of the membrane;
material released/expelled from the cell;
membrane flattens;
name of example e.g. exocytosis of neurotransmitter / exocrine secretion/
endocrine secretion / hormone secretion / release of cortical granules;
outline of example: (in the presence of calcium), neurotransmitter vesicles
release their contents into the synapse / hormones released from one cell
have an effect on another cell etc.;
Accept these points if clearly made in an annotated diagram. [4 max] if
no example given.	5 max
 
(c)	translation involves initiation, elongation/translocation and termination;
mRNA binds to the small sub-unit of the ribosome;
ribosome slides along mRNA to the start codon;
anticodon of tRNA pairs with codon on mRNA:
complementary base pairing (between codon and anticodon);
(anticodon of) tRNA with methionine pairs with start codon / AUG is the
start codon;
second tRNA pairs with next codon;
peptide bond forms between amino acids;
ribosome moves along the mRNA by one codon;
movement in 5′ to 3′ direction;
tRNA that has lost its amino acid detaches;
another tRNA pairs with the next codon/moves into A site;
tRNA activating enzymes;
link amino acids to specific tRNA;
stop codon (eventually) reached;	9 max
	(Plus up to [2] for quality)
[20]

36.	(a)	(i)	50 000 (Accept answers in the range of 50 000 to 53 000)	1
 
(ii)	0.1 µm (units required)
Allow answers in the range of 0.09 µm to 0.12 µm.	1

(b)	Award [1] for any two of the following.
growth/production of (extra) body cells; (do not accept cell growth)
first stage of spermato/oo/gametogenesis / forming oogonia/spermatogonia;
embryo development;

clonal selection / division of lymphocytes (for antibody production);
Do not accept asexual reproduction. Do not award a mark if one of the
first two answers is incorrect.	1 max
 
(c)	stem cells are undifferentiated cells;
embryo cells are stem cells;
stem cells can differentiate in many/all ways / are pluripotent/totipotent;
differentiation involves expressing some genes but not others;
stem cells can be used to repair/replace tissues/heal wounds;	3 max
 
(d)	(i)	estrogen and progesterone do not drop/continue rising (after day 21);
because corpus luteum continues to secrete them / embryo
secretes HCG;
to maintain/increase uterus lining/endometrium;	2 max
 
(ii)	Award [1] for any two of the following.
pre-natal development of male genitalia;
stimulates spermatogenesis / sperm production;
maintenance of sex drive/libido;
puberty / development of secondary sexual characteristics / penis
growth / pubic hair / body hair / facial hair / beard / deeper voice;
Do not award the mark if one of the first two roles given is
incorrect.	1 max
[9]

37.	A
[1]

38.	D
[1]

39.	C
[1]

40.	C
[1]

41.	(a)	anaphase	1
 
(b)	growth (through increasing cell number);
embryonic development;
tissue production/repair;
(asexual) reproduction;	2 max
 
(c)	uncontrolled mitosis/cell division	1
 
(d)	pair of homologous chromosomes moves in same direction/does not
separate during anaphase I / chromatids move in same direction/do
not separate during anaphase II;
leaving a cell with an (some) extra chromosome(s)/missing
chromosome(s);
an example; (e.g. Down syndrome / trisomy 21);	2 max
[6]

42.	C
[1]

43.	(a)	Award [1] for each structure clearly drawn and correctly labelled.
cell wall; (with some thickness)
plasma membrane; (shown as single line or very thin)
cytoplasm;
pilus/pili; (shown as single lines)
flagellum/flagella; (shown as thicker and longer structures than pili
	and embedded in cell wall)
70S ribosomes;
nucleoid / naked DNA;
approximate width 0.5 µm / approximate length 2.0 µm;
Award [3 max] if the bacterium drawn does not have the shape
of a bacillum (rounded-corner rectangle with length approximately
twice its width).
Award [3 max] if any eukaryotic structures included.	4 max

(b)	Accept the following points as a diagram if clearly drawn and
correctly labelled.
supercoiling of chromosomes in prophase;
chromosomes consist of sister chromatids in prophase;
formation of mitotic spindle / centrosomes/centrioles move away
in prophase;
nuclear membrane breaks down in (late) prophase/(early) metaphase;
attachment of spindle microtubules to centromeres;
chromosomes on metaphase plate/equator/centre of cell in metaphase;
parting of (sister) chromatids at onset of anaphase;
movement of sister chromosomes (accept chromatids) to opposite
poles in anaphase;
re-formation of nuclear membranes in telophase;
Award [5 max] if response does not mention all four phases of mitosis.	6 max
 
(c)	pyruvate produced by glycolysis;
pyruvate enters mitochondrion/mitochondria;
pyruvate loses CO2 in link reaction;
and NADH + H+;
with formation of acetyl CoA;
to take part in Krebs cycle;
where two CO2 are produced (per molecule of pyruvate);
one ATP from ADP + Pi;
along with (three) NADH + H+ (and one FADH2);
NADH + H+ provide electrons circulating in the electron transport
chain on the inner mitochondrial membrane;
allowing H+ to accumulate in the intermembrane space;
and come back to the matrix through ATP synthase/synthetase to produce
ATP (by chemiosmosis);
presence of O2 required as the final electron acceptor for the electron
transport chain;
producing water with H+;	8 max
	(Plus up to [2] for quality)
[20]

44.	C
[1]

45.	D
[1]

46.	B
[1]

47.	B
[1]

48.	D
[1]

49.	A
[1]

50.	D
[1]

51.	D
[1]

52.	C
[1]

53.	A
[1]

54.	A
[1]

55.	B
[1]

56.	(a)	Both name and function required to achieve [1].
A:	name: flagella/flagellum
	function: used for locomotion / beats in whip-like action to propel cell;
B:	name: pili/pilus
	function: used for adhesion (to another cell/surface) / transfer
of genetic material (between cells);
	ECF, for one mark, can be applied if both parts of the pair are reversed.	2
 
(b)	Award [1] for a similarity.
both have a plasma/cell membrane/ribosomes/cytoplasm/genetic material;
	Award up to [2] for differences. Candidate must make a valid
comparison, not simply describe each. Award [2 max] if features
of prokaryotic and eukaryotic cells are not compared directly,
item by item, although a table is not necessary.

Prokaryote	Eukaryote	
naked DNA	DNA associated with proteins;	
DNA in cytoplasm/no nucleus	DNA enclosed in nuclear envelope/membrane / nucleus;	
70S ribosomes	80S ribosomes;	
no membrane-bound organelles	internal membranes that form membrane-bound organelles;	
circular chromosome	linear chromosomes;	
fission	mitosis;	
no introns or exons	introns and exons;	
Smaller in size(approximately) 10 microns	larger in size up to (approximately) 100 microns;	
cell wall present	cell wall only present in plants/fungi;
Do not accept cell wall sometimes present.	
		3 max
[5]

57.	(a)	Award [1] for each of the following clearly drawn and correctly labelled.
phospholipid bilayer —double row of opposing phospholipids, tails to inside;
phospholipid —with head and two tails;
hydrophilic/phosphate/polar (heads) and hydrophobic/hydrocarbon/fatty
acid/non-polar (tails) labelled;
integral protein — embedded in the phospholipid bilayer;
protein channel — integral protein showing clear channel/pore;
peripheral protein—on the surface;
glycoprotein—with carbohydrate attached on one side;
cholesterol—shown embedded in bilayer;	5 max
 
(b)	vesicles formed from rER transport proteins to Golgi apparatus;
these vesicles fuse with membranes of Golgi apparatus;
proteins are processed as they move through Golgi apparatus;
(transport) vesicles bud off/leave Golgi apparatus;
vesicles move through cytoplasm;
(vesicles) fuse with plasma membrane;
contents released to outside of cell / exocytosis;
cells use vesicles to secrete substances such as hormones/digestive
enzymes/other appropriate example;
vesicles may contain cell products other than proteins;
Credit drawings which fully explain the points above.	6 max
 
(c)	To achieve [1] answer must name the structure and relate it to its function.
the villus has a large surface area to volume ratio;
microvilli increase surface area for absorption;
thin surface (epithelial) layer so products of digestion can pass easily through;
channel proteins located in plasma membrane used for facilitated diffusion;
network of capillaries inside each villus (so only short distance) for movement
of absorbed products;
capillaries transport absorbed nutrients/sugars and amino acids away from
small intestine;
blood flow in capillaries maintains concentration gradient;
central lymph vessel/lacteal to transport absorbed fats/fatty acids away from
small intestine;
large number of mitochondria provide ATP needed for active transport;
protein pumps in membrane (of microvilli) carry out active transport;
pinocytosis occurs at surface (epithelial) layer;
Accept any of the points above shown in a drawing.	7 max
	(Plus up to [2] for quality)
[20]

58.	(a)	has the ability to differentiate (into specialized tissue)	1

(b)	only some genes are expressed in each cell type/tissue;
tissues therefore develop differently/become differentiated;
example of differentiated cell and the function of tissues;	2 max
 
(c)	knowledge of location of human genes / position of human genes on
chromosomes;
knowledge of number of genes/interaction of genes / understanding
the mechanism of mutations;
evolutionary relationships between humans and other animals;
discovery of proteins / understanding protein function / detection
of genetic disease;
leads to the development of medical treatment/enhanced research
techniques;
knowledge of the base sequence of genes/study of variation within genome;	3 max
[6]

59.	(a)	Award [1] for each structure clearly drawn and correctly labelled, up to [4 max].
cell wall — a uniformly thick wall;
pili — hair-like structures / flagellum — at least length of the cell;

ribosomes — drawn as small discrete circles/shaded circles;
nucleoid — region with DNA not enclosed in membrane;
plasmid — circular ring of DNA;
cytoplasm —the non-structural material within the cell;
	Award [3 max] if one eukaryote structure is shown, [2 max] for
two eukaryote structures, [1 max] for three eukaryote structures
and [0] if four or more eukaryote structures are shown.	4 max
 
(b)	light: [2 max]
rate increases with increasing light;
it reaches maximum then plateaus;
as all chloroplast molecules are working at optimal pace;
	temperature: [2 max]
rate increases with increasing temperature;
to a maximum/optimum temperature;
but then falls off rapidly;
as enzymes are denatured above the optimal temperature;
	carbon dioxide: [2 max]
rate increases with increasing carbon dioxide level;
it reaches maximum then plateaus;
as photosynthesis operating at optimal level;
	Award any of the above points if clearly drawn in a diagram.	6 max

(c)	increase in temperature is called global warming;
this is caused by the greenhouse effect;
a natural phenomenon that has occurred over millions of years;
main gas responsible is carbon dioxide;
other gases like methane/nitrous oxide also cause effect;
shortwave radiation from the Sun enters atmosphere;
warms the surface of the Earth;
longwave radiation emitted by the surface of the Earth;
is absorbed by carbon dioxide/greenhouse gases;
human use of fossil fuels has increased levels of atmospheric carbon dioxide;
rapid rise in temperatures over (approximately) hundred years;
cows/animals/peat bogs release methane;
greenhouse gases emitted by volcanic activity;	8 max
	(Plus up to [2] for quality)
[20]

60.	C
[1]

61.	(a)	Award [1] for each structure clearly drawn and correctly labelled.
Whole cells not necessary.
(plasma) membrane—single line surrounding cytoplasm;
nucleus — with a double membrane and pore(s) shown;
mitochondria(ion) — with a double membrane, the inner one folded
into internal projections, shown no larger than half the nucleus;
rough endoplasmic reticulum—multi-folded membrane with dots/
small circles on surface;
Golgi apparatus—shown as a series of enclosed sacs with evidence
of vesicle formation;
ribosomes — dots/small circles in cytoplasm/ribosomes on rER;
lysosome;
Award [0] if plant cell is drawn. Award [2 max] if any plant cell
structure (e.g. cell wall) is present.	4 max

(b)
prokaryotic	eukaryotic	
naked DNA	protein associated with DNA;	
DNA in cytoplasm / nucleoid / no nucleus	DNA in nucleus / nucleus present;	
circular DNA	linear chromosomes/DNA molecules;	
no mitochondria	mitochondria;	
70S ribosomes present	80S ribosomes present;	
no membrane bound organelles	internal membranes form organelles;	
pili present	pili absent;	
plasmids (sometimes) present	plasmids absent;	
cell wall present	cell wall only present in plants/fungi;
Do not accept cell wall sometimes present.	
flagella solid	flagella flexible/membrane-bound;	
		6 max
 
(c)	DNA replication is semi-conservative / each strand of DNA
acts as template;
(DNA) helicase separates two strands/forms a replication fork;
new strand built / nucleotides added in a 5´ to 3´ direction;
(deoxy)nucleoside triphosphates hydrolysed to provide energy for
nucleotide formation/base pairing;
on one strand DNA polymerase III builds continuous strand;
on other strand short chains of DNA/Okazaki fragments are formed;
each short chain starts with RNA primer;
added by RNA primase;
then remainder of chain of DNA built by DNA polymerase III;
DNA polymerase I removes RNA primer and replaces it by DNA;
DNA ligase joins DNA fragments together forming complete strand;
replication only occurs at a single replication fork;
Award credit for any of the above points clearly drawn and accurately
labelled.	8 max
	(Plus up to [2] for quality)
[20]

62.	A
[1]

63.	B
[1]

64.	C
[1]

65.	D
[1]

66.	D
[1]

67.	(a)	Award [1] for each structure clearly drawn and correctly labelled.
phospholipid bilayer — with head and tails;
hydrophilic/phosphate/polar heads and hydrophobic/hydrocarbon/fatty
acid/non-polar tails labelled;
integral protein —embedded in hydrophobic region of the phospholipids
bilayer;
protein channel—integral protein showing clear channel/pore;
peripheral protein—on the surface;
glycoprotein with carbohydrate attached on outside;
cholesterol — shown embedded in bilayer;
thickness indicated (10 nm); (allow 7 nm to 13 nm)	5 max

(b)
passive	active	
Diffusion / osmosis / facilitated diffusion	active transport / ion pumps / exocytosis / pinocytosis / phagocytosis	
a second passive method (from above)	a second active method; (from above)	
does not require energy	requires energy/ATP; 	
down concentration gradient	against concentration gradient;	
no pumps needed	requires protein pumps;	
oxygen across alveoli / other example	glucose absorption in ileum / other example;	
	Both the passive and active movements must be contrasted to
receive a mark.
Award [3 max] if no examples are given. Responses do not
need to be shown in a table format.	4 max
 
(c)	water is transparent / light passes through water;
this allows organisms to live below the surface / plants to photosynthesize;
hydrogen bonds between water molecules make water cohesive;
this gives water a high surface tension allowing animals to live on the
surface / maintains lung structure (pleural membranes);
helps in water movement through plants/transpiration;
water has a high latent heat of vaporization / OWTTE;
evaporation/sweating/transpiration leads to cooling;
water has a high specific heat capacity / OWTTE;
this provides a stable environment for water organisms;
water is a universal solvent;
can transport materials around organisms/plants/animals;
can be a solvent for chemical reactions in organisms;
ice is less dense than water / water has a maximum density at 4°C;
surface (pond/lake/ocean) freezes first, allowing organisms to survive
in the water below;
Accept hydrogen bonds between water and other substance makes water
adhesive from AHL.	9 max
	(Plus up to [2] for quality)
[20]

68.	C
[1]

69.	(a)	Award [1] for each structure clearly drawn and correctly labelled.
cell wall —with some thickness;
plasma membrane — shown as single line or very thin;
cytoplasm;
pilus/pili — shown as single lines;
flagellum/flagella —	shown as thicker and longer structures than pili
	and embedded in cell wall;
70S ribosomes;
nucleoid / naked DNA;
approximate width 0.5 µm / approximate length 2.0 µm;
Award [4 max] if the bacterium drawn does not have the shape of a
bacillum (rounded-corner rectangle with length approximately twice
its width).
Award [4 max] if any eukaryotic structures included.	5 max

(b)
passive	active	
Diffusion / osmosis / facilitated diffusion	active transport / ion pumps / exocytosis / pinocytosis / phagocytosis	
a second passive method (from above)	a second active method; (from above)	
does not require energy	requires energy/ATP; 	
down concentration gradient	against concentration gradient; 	
no pumps needed	requires protein pumps; 	
oxygen across alveoli / other example	glucose absorption in ileum / other example;	
	Both the passive and active movements must be contrasted to
receive a mark.
Award [3 max] if no examples are given. Responses do not need
to be shown in a table format.	4 max

(c)	occurs during aerobic respiration;
oxidative phosphorylation occurs during the electron transport chain;
hydrogen/electrons are passed between carriers;
releasing energy;
finally join with oxygen (to produce water);
occurs in cristae of mitochondria;
chemiosmosis is the movement of protons/hydrogen ions;
protons move/are moved against their concentration gradient;
into the space between the two membranes;
protons flow back to the matrix;
through the ATP synthase/synthetase (enzyme);
energy is released which produces more ATP/combines ADP and Pi;	9 max
	(Plus up to [2] for quality)
[20]

70.	C
[1]

71.	D
[1]

72.	D
[1]

73.	C
[1]

74.	B
[1]

75.	(a)	(osmosis is) the passive movement of water / solvent molecules from a
more dilute solution / region of lower solute concentration to a more
concentrated solution / region of higher solute concentration through
a partially permeable membrane	1
 
(b)	facilitated diffusion is a form of passive transport / molecules move from a
region of higher concentration to a region of lower concentration / down a
diffusion gradient;
requires specific protein channels in plasma membrane;	2
 
(c)	phospholipds have hydrophilic and hydrophobic regions;
hydrophilic heads attracted to water and hydrophobic / fatty acid tails repelled
by / not attracted to water;
phospholipd bilayer forms with heads in contact with water on both sides of
membrane / with environment and cytoplasm;
hydrophobic tails found in centre (of bilayer) away from water;
stability to membrane brought about by attraction between hydrophobic
tails / between hydrophilic heads and water;	3 max
[6]

76.	(a)	Award [1] for each structure clearly drawn and correctly labelled.
	nucleus—smaller area than cytoplasm, surrounded by double membrane
with pores;
	mitochondrion—surrounded by double membrane, inner membrane has
infoldings;
	rough endoplasmic reticulum—stacked tubules with dots / small circles
on outer surfaces;
	Golgi apparatus—curved stacked tubules, small vesicles near ends of
tubules / sacs;
	ribosomes both attached to rER and free ribosomes in cytoplasm drawn
and labelled;
lysosome / nucleolus / nuclear envelope / nuclear pore / plasma membrane;	4 max
Award [0] if a plant cell is drawn.
Award [3 max] if a plant cell structure (such as the cell wall) is present.
 
(b)	during interphase DNA replicates / produces two copies of genetic material;
sister chromatids are two identical DNA molecules held together by centromere;
sister chromatids are separated during mitosis to form two genetically
identical nuclei;
in prophase chromosomes shorten / thicken / become visible as double-stranded
chromosomes / joined sister chromatids;
chromosomes condense by supercoiling;
chromosomes attach to spindle microtubules at centromeres;
chromosomes begin to move towards equator / centre of cell;
during metaphase all chromosomes lined up at equator separately / not in
homologous pairs;
at start of anaphase centromeres divide separating sister chromatids;
separated sister chromatids known as (single stranded) chromosomes;
(identical sets of) chromosomes pulled to opposite poles;
move by contraction of microtubules;
nuclear envelope / membrane forms around each set of chromosomes;	8 max
Many of these points can be shown by correctly annotated diagrams.
Credit may be given for diagrams clearly illustrating these points.

(c)	Award [4 max] for any of the following general statements:
stem cells are cells that retain the capacity to divide and have the ability to
differentiate along different paths into all types of cells / are pluripotent / totipotent;
stem cells are derived from blastocysts / human embryos, left over from
IVF / placenta / umbilical cord / some adult tissues;
new techniques / technologies rely on replacing diseased / dysfunctional cells with
healthy / functioning ones;
need to identify desired type of stem cell and grow in culture / special
solutions / controlled conditions;
develop biochemical solution that will cause cells to differentiate into desired
cell type;
develop means of implanting / integrating cells into patient’s own tissues so that
they function with the body’s natural cells;
danger of rejection of cells therefore need to suppress immune system;
must make sure new cells do not become overgrown / develop into
cancerous tumours;
Award [2 max] for a specific example ie: [1] for type of cells and [1] for proposed use:
eg retinal cells;
replace dead cells in retina to cure presently incurable diseases such as glaucoma
and macular degeneration;
eg graft new skin cells;
to treat serious burn victims;
eg nerve tissue;
help repair catastrophic spinal injuries / help victims of paralysis
regain movement;	6 max
(Plus up to [2] for quality)
[20]

77.	D
[1]

78.	(a)	Award [1] for each of the following clearly drawn and labelled correctly.
a double layer of lipid / phospholipid molecules — with hydrophilic heads and
hydrophobic tails;
an integral protein —passing completely through the lipid bilayer;
a peripheral protein — shown on the surface and not penetrating the lipid bilayer;
an integral protein with a pore passing through its entire length / a glycoprotein
with the carbohydrate components shown / cholesterol as component in bilayer;	4

(b)	chlorophyll is composed of a number of pigments;
absorb different colours of light;
mainly red and blue absorbed;
green light reflected;
temperature increases rate;
up to a point where enzymes denature;
light intensity increases rate;
up to a point where maximum absorbance can occur;
carbon dioxide increases rate;
up to a point where fixation is at a maximum;	6 max
 
(c)	Krebs cycle:[3 max]
in matrix of mitochondrion;
decarboxylation;
oxidation / removal of hydrogen by NAD and FAD;
substrate level phosphorylation;
Electron transport chain:[5 max]
transfer of hydrogen to inner membrane carriers;
hydrogen ion pumped across inner membrane;
creates a concentration gradient;
electron transferred between carriers;
chemiosmosis;
hydrogen ion passes down concentration gradient;
through ATPase complex;
oxygen is final acceptor forming water;	8 max
(Plus up to [2] for quality)
[20]