1.	(i)	award both marks for correct answer
evidence of 14.7 - 2.2 = 12.5 or 14.7 / 2.2 gains one calculation mark
	12.5/2.2 × 100;
= 568.2 / 568 / 570;;	2
 
(ii)	protein converted to amino acids;
excess amino acids undergo deamination / removal of amino group;
ammonia formed;
ammonia converted to urea;
	AVP; e.g. ref. to ornithine cycle	max 3
[5]

2.	conversion of one amino acid to another / AW;
(free) amino acids in body may not match body’s requirements / AW;
can only occur with non-essential amino acids;	2 max
[2]

3.	(i)	award two marks if correct answer (568.18 / 568.2 / 568 / 570) is given
evidence of 14.7 – 2.2 = 12.5 or 14.7/2.2 gains one calculation mark
12.5/2.2 × 100 = 568.18 / 568.2 / 568 / 570 ; ;	2
(ii)	(more) proteins to amino acids ;
ref to deamination / removal of amino group ;
(more) ammonia formed ;
ref to ornithine cycle ;
(more) ammonia converted to urea ;	2 max
[4]

4.	A – sinusoid ;
B – (branch of) bile duct ;
C – (branch of hepatic) portal vein / HPV ;
D – (branch of) hepatic artery ;
[4]

5.	bile pigments build up in blood ;
(pigments) do not enter gut / AW ;
AVP ; e.g. bile, canaliculi / duct, blocked / gall stones	2 max
[2]

6.	(i)	long loop of Henlé or/ deep / wide, medulla ;
very low water potential in medulla / AW ; A higher concentration of salts
collecting duct more permeable to water ;
large number of, water permeable channels / aquaporins, in collecting duct ;
more sensitive to ADH / more ADH produced ;
AVP ; e.g. other correct ref to kidney histology
	all loops of Henlé are long
	CD more permeable to urea
	more capillary loops in medulla	3 max
(ii)	seeds contain, storage molecules / AW ; A named example of storage
molecule
aerobic ;
respiration ;
water is produced ; linked to respiration
R reference to condensation reactions
accurate equation for aerobic respiration can gain 3 marks
metabolic water = 2 marks	3 max
[6]

7.	(a)	(i)	noradrenaline / adrenaline / thyroxine / growth hormone
/ glucocorticosteroid;	R steroid	1
(ii)	insoluble;
unreactive / stable / inert;
cannot diffuse out of cell / AW;
no effect on water potential;
compact / branched;
	lots of glucose in small space / AW;	R lots of energy in
small space
easy to, convert to glucose / hydrolyse;
lots of ‘ends’ for enzyme action;	max 3
 
(b)	1	increases activity of glycogen synthetase;
2	slow initial effect / AW;
3	ref to figures to show an increase;
4	(overall effect) increases, production of glycogen
/ glycogenesis;	R storage of
5	glycogen
6	lowers activity of glycogen phosphorylase;
7	rapid effect;
8	ref to figures to show a decrease;
9	prevents / reduces, breakdown of glycogen / glycogenolysis;
10	(glucose binds to) allosteric site / AW;
(glucose acts as) inhibitor / activator;	R competitive inhibitor	max 5

(c)	either
deamination of amino acids / removal of NH2 from amino acids;
pyruvate / carbon skeleton / AW;
triose phosphate / TP;
condensation / increasing number of carbon atoms;
or
breakdown of, lipid / triglyceride;
glycerol;
triose phosphate / TP;
condensation / increasing number of carbon atoms;	max 3
[12]

8.	(a)	ref parasympathetic NS / AW;
sympathetic NS less active / AW;
more impulses in vagus nerve / less impulses in accelerator nerve;
more acetylcholine / less noradrenaline;
effect on SAN;	max 3
 
(b)	any two of
fibrinogen;	R fibrin
prothrombin;	R thrombin
albumin;	A albumen
(named) globulin;	R immunoglobulin or antibodies
AVP; e.g. transferrin	max 2
 
(c)		similarities
1	production of urea;
2	urea transported in blood;
3	urea filtered from blood;
4	synthesis of proteins from amino acids;
	differences (assume refs are to brown bears unless otherwise stated)
5	amino acids synthesised from ammonia;
6	all urea reabsorbed;
7	from kidney and bladder;
8	urea converted to ammonia by bacteria;
9	AVP; e.g. (humans) less tolerant to high ammonia (in blood)	max 5
 
(d)	component of cell membranes / AW;
ref to, mechanical stability / impermeability / fluidity;	ignore rigidity
production of, steroid hormone / named hormone;
production of vitamin D;
production of bile salts;	max 3

(e)	increases high density lipoproteins (HDLs);
reduces low density lipoproteins (LDL);
prevents, deposition of cholesterol / plaques / atherosclerosis;	max 2
[15]

9.	(i)	Mark the first answer. If the answer is correct and an additional answer is given that is incorrect or contradicts the correct answer then = 0 marks
	ultrafiltration;
This term required but ACCEPT phonetic spelling
1
 
(ii)	17.9;;
Correct answer = 2 marks
If answer incorrect, not rounded or incorrectly rounded then allow 1
mark for working
	125 ÷ 700
	or
	an unrounded answer e.g. 17.857412
2
[3]

10.	(i)	Mark the first answer. If the answer is correct and an additional answer is given that is incorrect or contradicts the correct answer then = 0 marks
	(cuboidal) epithelium / epithelial;
DO NOT CREDIT ‘epithelium cells’ / ‘ciliated epithelium’ / ‘squamous epithelium’ / endothelium
ALLOW columnar epithelium
1
 
(ii)	Mark the first answer. If the answer is correct and an additional answer is given that is incorrect or contradicts the correct answer then = 0 marks
	microvilli / microvillus;
ACCEPT ‘brush border’
DO NOT CREDIT cilia
1

(iii)	This is a QWC question
	1	selective reabsorption;
2	of glucose and amino acids;
DO NOT CREDIT if glucose & amino acids & proteins
3	co-transport / facilitated diffusion / uptake described;
ACCEPT direct uptake, of glucose / amino acids,
by active transport
4	water follows by osmosis so concentration of, ions / nitrogenous
waste / urea / remaining substances, increases;
5	AVP;
e.g. 
•	microvilli provide large surface area for uptake
•	many mitochondria provide energy for uptake
•	many brush border enzymes (ATPase) for active uptake
•	active secretion of nitrogenous waste into lumen
3 max
	QWC - technical terms used appropriately and spelt correctly;
Use of three terms from:
reabsorption (or derived term),
co-transport (or derived term),
facilitated diffusion, osmosis
1
[6]

11.	(i)	L	artery / shunt / vein (at arterial end of shunt)
	AND
M	vein;
IGNORE names of artery / vein (e.g. renal)
DO NOT CREDIT aorta and vena cava
1
 
(ii)	so that clots don’t form,
while in the (dialysis) machine / during dialysis;
ALLOW congeal instead of clot
IGNORE prevents clotting in the body
IGNORE clumping
1
 
(iii)	idea of allowing blood to clot normally after treatment;
CREDIT preventing low blood pressure (as low viscosity)
1

(iv)	Mark the first answer. If the answer is correct and an additional answer is given that is incorrect or contradicts the correct answer then = 0 marks
	(simple) diffusion;
IGNORE dialysis
DO NOT CREDIT facilitated diffusion
1
 
(v)	idea that it,
	maintains diffusion gradient /
IGNORE unqualified ref to countercurrent
	maintains concentration gradient /
	maximises diffusion gradient /
	maximises concentration gradient /
e.g.
•	solutions in contact over greater distance
•	provides maximum contact for exchange
•	allows exchange over longer distance
	allows maximum removal of waste /
	allows maximum rate of diffusion / AW;
IGNORE ref to surface area
1
[5]

12.	the longer the loop of Henle the lower the water potential (of urine); ora
ions pass out from ascending limb into, medulla / tissue fluid;
creating lower water potential in the medulla / AW;
water reabsorbed from collecting duct in medulla;
by osmosis; (linked to previous marking point)
	AVP; e.g. ref to countercurrent multiplier	max 3
[3]

13.	1	frequent need to urinate/diuresis;
2	large volume of urine/very dilute urine;
3	persistent feeling of thirst/excessive drinking;
4	electrolyte/mineral, imbalance;
5	AVP; e.g. dehydration,	3 max
[3]

14.	(a)	(i)	wide / large, afferent arteriole;
narrow / small, efferent arteriole;
	afferent arteriole, wider / larger, than efferent arteriole – 2 marks
	ref to ‘bottleneck’ effect / AW; R build up pressure on own
to achieve filtration;
must be greater than 6.7 kPa for filtration;	2 max
 
(ii)	award two marks if correct answer (1.3) is given
incorrect answer (or no answer) but correct working = 1 mark
	8 – (4 + 2.7) A 8 – 6.7
1.3;;	2
 
(b)	(i)	(too) large / RMM greater than 69000 or 70000;
to pass through basement membrane;	2
(ii)	glomerular blood pressure is greater;
proteins forced through;
damage to capillaries / AW;
damage to basement membrane;	2 max
 
(c)	1	endothelium of capillaries;
2	large / many, fenestrations / gaps / holes;
3	modified epithelial cells of capsule / podocytes;
4	slit pores / foot-like processes; A finger like
5	basement membrane;
6	made up of, collagen / glycoproteins / molecular mesh;
	accept annotated diagrams	4 max
 
(d)	1	volume will increase;
2	concentration decrease;
3	(wall of), collecting duct / DCT, (relatively) impermeable to water;
4	fewer water channels; A aquaporins
5	in membrane of epithelial cells;
6	less water reabsorbed (from the urine);
7	by osmosis (linked to marking point 6);
8	drinking increases liquid intake and therefore liquid loss;	4 max
[16]

15.	CG acts as antigen;
move, attached to, free antibodies;
attach to, immobilised antibody;
coloured particles, form line;
ref to complementary shapes;
ref to antigen, antibody complex;
AVP; e.g.	further detail of antibody structure
	monoclonal
	CG-antibody complex	4 max
[4]

16.	1	both filtered / AW ;
2	both small molecules / AW ; A RMM close to 69 000
3	(all filtered) glucose reabsorbed ;
4	active uptake, carrier / cotransporter, proteins ;
5	(some) glucose used in, respiration / active processes, in kidney ;
6	some urea reabsorbed ;
7	by diffusion ;
8	ref to reabsorption in PCT ; apply once to either glucose or urea	5 max
[5]

17.	ADH / anti diuretic hormone ;
reduces blood sugar levels / correct mechanism to achieve this ;
increases blood sugar levels / correct mechanism to achieve this ;
ABA / abscisic acid ;
auxin / IAA ;
[5]

	5 max
[5]

18.	(i)	directly proportional / AW ;	1
(ii)	2.6 ;	1
(iii)	1	high levels of glucose in glomerular filtrate ;
2	unable to reabsorb all glucose (in, PCT / kidney tubule) ;
		A no more glucose can be reabsorbed
3	ref to glucose carriers / AW ;
4	at threshold value carriers, all saturated / limiting factor ;
5	AVP ; e.g. ref to renal threshold	3 max
[5]