1.	(a)

		
(All symbols in a column need to be correct for a mark)	2
(b)	(i)	chloroplast;
grana / thylakoids;	2
(ii)	nucleus;
chromosomes / chromatin / chromatids;	2
[6]

2.	(a)	(i)	ATP used;
movement is against a concentration gradient;	2
(ii)	stops / less movement of ions;
movement of ions needs ATP;
ATP / production linked to respiration /
electron carrier system;	max. 2
 
(b)	(i)	greater concentration difference / increased gradient therefore more
molecules move in external concentration limiting factor /
increased concentration increases rate;	1
(ii)	(limit imposed in situation B by)
limited number of molecules can move through the pores in unit time /
pores are full / number of pores is limiting factor;	1
[6]

3.	(a)	Two marks for correct answer of 3000;
One mark if answer obtained by dividing actual length by 20 m;	2
 
(b)	(i)	Letter A indicating cytoplasm;	1
(ii)	Letter B indicating ribosome;	1
 
(c)	Cristae are site of ATP synthesis/oxidative phosphorylation;
by electron/hydrogen carriers;
Metabolism requires energy input/ATP;	max 2
[6]

4.	(a)	4 micrometres = 2 marks (Allow 3.9 - 4. 1)
Correct method of scaling, but incorrect conversion to micrometres = 1	2
 
(b)	(i) not in nucleus / single (loop) chromosome.	1
(ii)	not attached to ER / smaller (70S).	1
(iii)	not in mitochondria / attached to mesosomes.	1
 
(c)	increases concentration (of solutes) inside bacteria / decreases
water potential inside bacteria;
less / no net water loss to external solution or uptake of water
to more conc. solution inside.	2
[7]

5.	(a)	Bacteria do not have a nucleus/nuclear membrane, eukaryote does;
Bacteria do not have membrane-bound organelles, eukaryote does;
Bacteria do not have mitochondiia, eukaryote does;
Bacteria has 70S/smaller ribosomes, eukaryote has 80S/larger;
Bacteria] cell-, have murein/peptidoglycan cell wall, eukaryotes do not-.
Bacterial cells are very much smaller than eukaryotic cells;
Bacteria have circular DNA, eukaryotes have linear DNA;
Bacteria may have capsules, eukaryotes do not;	2
 
(b)	(i)	flagellum
(ii)	ribosome
(iii)	plasmid	3
[5]

6.	(a)	(i)	Crista	1
(ii)	(Mitochondria) provide energy / ATP;
liver cells have high energy requirement for metabolism- reactions
specific liver function, eg. glycogen synthesis or deamination (not just:
active transport/ growth)	2
(iii)	Principle - protein synthesis;
Function of protein in mitochondria - e.g. synthesis of (respiratory)
enzymes / growth / repair / replication.
or:
DNA has genetic information;
ribosomes produce proteins / allows replication of mitochondria.	2
 
(b)	Maintain concentrations/water potential same inside & outside (cells /
mitochondria) / prevent osmosis;
Prevent bursting / shrinkage of mitochondria/organelles (not cells)	2

(c)	Eukaryotic ribosomes denser/ heavier (not just ‘larger’).	1
[8]

7.	(a)	(i)	Nucleus;	1
 
(ii)	Correct answer (3µm = 2 marks)
error with measurement, but clearly derived by dividing drawing size
by magnification = 1 mark;	2
 
(b)	(i)	Ice-cold – prevents enzymes working/autolysis/self digestion;
(ii)	Isotonic – prevents osmotic effects to organelles/osmosis/bursting/
shrinking;	2
 
(c)	A;
Nucleus is largest/densest/heaviest organelle (sediments first/lowest spin speed);
(Reject reference to plant organelles/cell wall)	2
 
(d)	O2 uptake / ATP production / CO2 production (not respiration / heat);	1
[8]

8.	(a)	A  ribosome (RER neutral);	1
	B  vacuole;	1
	C  smooth ER / SER;	1
(b)	(i)	support / strength / shape / prevents osmotic lysis;
(protection, permeability neutral)	1
(ii)	photosynthesis / light energy ® chemical energy;
(makes food/sugar neutral)	1
 
(c)	0.2 – 0.24 gains 2 marks;
ELSE evidence of observed measurement
(5 – 6 mm / 0.5 – 0.6 cm) ÷ 25 000
gains one mark;	2
[7]

9.	(a)	(i)	microvilli; (reject brush border)	1
(ii)	increased surface area (for diffusion);	1
(b)	(i)	/ principle of; (15 –17 tolerance)
	160000; (correct answer award 2 marks)	2
(ii)	electron microscope has a greater resolving power / objects closer 
together can be distinguished; 
electron (beams) have a shorter wavelength;	2
(c)	short diffusion pathway /short pathway to the centre / large SA:V ratio
for faster, more diffusion;	1
[7]

10.	(a)	Glycerol / glyceride;	1
(b)	(i)	Phospholipid has (one) phosphate / Phosphoric acid;	2
replacing fatty acid;
(ii)	Saturated – all valencies of C filled / saturated with hydrogen / all (C–C)
single bonds / no double bonds;
fatty acid 1 is saturated/fatty acids 2 and 3 are unsaturated;	2
[5]

11.	(a)	(Crush in) ethanol / alcohol;
Add (to) water  (Order of adding is critical for this point);
Emulsion / white colour;	3
(b)	(i)	Glycerol / glyceride;	1
(ii)	Phospholipid has phosphate / phospholipid only has two fatty acids;	1
(iii)	Phosphorus / P;	1
 
(c)	(i)	Both membranes contain phospholipid / lipid (bilayer);	1
(ii)	Glucose unable to pass through artificial membrane as not lipid soluble;
Glucose transported by proteins;
(Proteins) found in plasma membrane /
not found in artificial membrane;	max 2
[9]

12.	(a)	(i)	4;	1
(ii)	Not made of identical units/ monomers/ made of fatty acids and glycerol;	1

(b)	(i)	A   O(xygen);
B   C(arbon);	2
(ii)	No double bonds/ every carbon joined to two hydrogens/ four-other atoms;	1
 
(c)	(i)	2 marks - Correct answer of 0.0000025/ 2.5 × 10-6 ;;
	1 mark - Incorrect answer but clearly derived from volume divided
	by surface area;	2
[Note: Assume units are mm unless otherwise stated]
(ii)	Head hydrophilic/ attracted to water/ polar;
Tail hydrophobic/ avoids/ shuns water/ non-polar;	2
[Allow: only one mark for limited references to “loving”
and “hating” water]
[9]

13.	(a)	(i)	More “free” water molecules outside cell / in distilled water;
water molecules inside cell “bound” to solute molecules;
link between water molecules, pressure they exert and water potential;
water potential of distilled water =0;
presence of solute reduces water potential;	max 2
(ii)	Partially permeable / only allows water molecules through /
does not allow solute molecules though;	1
 
(b)	Passive / does not require ATP;   R energy not required
movement down gradient; R across
does not require carrier molecules / not facilitated;	max 2
[5]

14.	(a)	(Small alveoli with) large surface area;
For diffusion;	2
 
(b)	(i)	Epithelium / epithelial/squamous/pavement cells;	1
Reject endothelium.
 
(ii)	0.11 mm;	1
 
(c)	(i)	Less oxygen / more carbon dioxide / more water vapour;	1
Two differences required, but only one mark for this part of the question.
 
(ii)	Gas exchange takes place in alveoli / does not take place in trachea;	1

(d)	(i)	Pulmonary artery;	1
 
(ii)	Concentrations reach equilibrium/become equal;
Diffusion occurs when there is a concentration gradient (so some will
remain in blood);
OR
Lung cells/vessel cells respire;
Add/produce carbon dioxide;	2
[9]

15.	(a)	two of the following:
form(water) impermeable barrier to water-soluble substances / selectively
permeable / allows non-polar molecules to pass through;
allows cell to maintain different concentrations either side;
makes membranes self-sealing/able to fuse with other
membranes/able to form
vesicles / gives flexibility/fluidity;	2 max
 
(b)	(surface/extrinsic protein) for cell recognition / binding to
hormones/identification	1
 
(c)	(i)	involves carrier/transmembrane/transport proteins;	1
(reject channel proteins)
 
(ii)	requires energy/requires use of ATP / moves substances/ions/molecules
against a concentration gradient;	1
 
(iii)	the curve levels off above a certain external concentration of substance;
as channel proteins are saturated with molecules
(and no more can be carried);	2
[7]

16.	(a)	effective water / sewage treatment / prevent water contamination /
improved hygiene / vaccination / quarantining of affected area; (any two)	1
(b)	oral rehydration therapy/ORT;
replaces lost water and salts;
OR
drinking large amounts of water;
with salts/minerals;	2

(c)	(i)	(protein/poison) excreted / secreted by bacteria;	1
(ii)	receptor / proteins on membrane;
complementary shape of exotoxin;	2
(d)	(i)	active transport;
using ATP / carrier proteins;	2
(ii)	higher solute concentration / water potential lowered in small intestine;
osmotic loss of water;	2
[10]