Mark scheme
Section 1
(a)  any two from:
•   sterilise equipment / surfaces (before use)
•   (use) sterilised agar
ignore ‘clean’ unqualified
ignore wash hands
allow description of how to sterilise equipment
allow description of how to sterilise agar
•   secure lid of the Petri dish with (adhesive) tape
•   only lift lid of Petri dish a little (when setting up plate) or lift lid of Petri dish at an angle (when setting up plate)
2
(b)  B
and
it kills the fewest bacteria
or
it has the smallest area where no bacteria were growing
allow it has the smallest clear / white area
an incorrect answer for one step does not prevent allocation of marks for subsequent steps
ignore calculation and subtraction of filter paper disc area from total area
1
(c)  (correct measurement)
r = 1.1 (cm)
or
r = 11 (mm)
allow d = 2.2 (cm)
or
d = 22 (mm)
allow a tolerance of ±1 mm
1
(recall of the equation)
πr2
1
(calculation/substitution)
3.14 x 1.12
or
3.14 x 112
allow correct calculation / substitution using an incorrect measurement
1
= 3.799(4) (from 3.14 x 1.12)
or
= 379.9(4) (from 3.14 x 112)
allow 3.8
allow 380
1
correct unit
(3.7994) cm2
or
(379.94) mm2
do not accept unit with no attempt at working / answer
1
(d)  any one from:
•   repeat and calculate a mean
•   repeat and eliminate anomalies
•   use a control disc
allow description of control disc e.g. disc with water / nothing ignore set up a control
•   use different types of bacteria
1
[9]
Section 2
(a)     any two from:
•   regular hand washing
or
use hand sanitiser / alcohol gel
•   cover nose / mouth when coughing / sneezing
allow wear a face mask
•   put used tissues (straight) in the bin
•   don’t kiss uninfected people
allow isolate patient from others
or
don’t share cutlery / cups / drinks with uninfected people
•   clean / disinfect / sterilise surfaces regularly
ignore responses referring to infected people
2
(b)     any three from:
•   stimulate (mouse) lymphocytes to produce antibody
for marking points 1 and 2 lymphocyte must be used at least once
•   combine (mouse) lymphocyte with tumour cell
or
(create a) hybridoma
•   clone (hybridoma) cell
•   (hybridoma) divides rapidly and produces the antibody
3
(c)     any two from:
•   (monoclonal) antibody binds to virus or antibody binds to antigen on surface of virus
•   (monoclonal) antibody is complementary (in shape) / specific to antigen (on surface of virus)
•   white blood cells / phagocytes kill / engulf the virus(es)
2
(d)     as a control
or
to see / compare the effects of the treatment (vs. no treatment)
1
(e)     (4.8 + 10.4) ÷ 2 ÷ 100 × 1500
or
(4.8 ÷ 100 × 750) + (10.4 ÷ 100 × 750)
1
114
an answer of 114 scores 2 marks
allow 228 for 1 mark
1
Section 3
(a)  mechanical
allow physical
allow structural
1
(b)  any one from:
•   to deter herbivores
ignore to injure animals, unqualified
allow to deter animals eating it
do not accept to deter predators
•   to prevent animals damaging it
1
(c)  chemical
1
(d)  any two from :
•   lack of magnesium (ions) (1)
(so) not enough chlorophyll for (efficient) photosynthesis (1)
(so) not enough glucose to make proteins for growth
or not enough glucose to release energy for growth (1)
allow (so) lack of chlorophyll produced causes yellow leaves (1), (so) not enough
photosynthesis to produce glucose which is used to make proteins for growth (1)
•   infection by pathogen / bacteria / virus / fungus (1)
allow correctly named pathogen
allow has rose black spot / TMV
(so) leaves become discoloured / yellow so less photosynthesis (1)
allow other symptoms of named pathogens / disease
(so) not enough glucose to make proteins for growth or not enough glucose to release energy for growth (1)
award once only
•   infected by aphids (1)
(which) remove sugars from phloem (1)
(so) not enough glucose to make proteins for growth or not enough glucose to release energy for growth (1)
award once only
•   lack of (available) light (1)
(so) chlorophyll breaks down (1)
(so) not enough glucose to make proteins for growth or not enough glucose to release energy for growth (1)
award once only
5

[8]
Section 4
(a)  A
1
(b)  cerebral cortex
allow cerebrum
allow cerebral hemisphere(s)
ignore D
1
(c)  any three from:
•   can ask people to do different tasks (while taking scan)
allow can ask person to do a (specific) task
•   to see which part of brain is active / inactive
allow to see which part of the brain is working
•   to compare with a person without brain damage
•   to see (exactly) where the damage is
•   (traditional) MRI scanner cannot be used if people can’t stay still
allow examples such as children or patients with Parkinson’s disease
allow may be better for people who are claustrophobic
3

Section 5
(d)  (cells in) retina sensitive to light
allow retina detects light
allow rods / cones detect light
1
impulse passes along (sensory) neurone
allow electrical signal or electrical message passes along (sensory) neurone
1
(along) optic nerve
allow chemical transmission across synapse
1
Section 6
blood vessels supplying skin
1
constrict
allow vasoconstriction
do not allow capillaries /veins constricting
do not allow moving blood vessel
1
less blood flow (to / through capillaries / to skin)
allow blood flows further away from skin surface
1
so less energy is lost (to the surroundings)
allow less heat is lost
1
‘shivering’ by muscle (contraction)
allow muscles contract (and relax) rapidly
1
releasing energy or respiring (more)
allow ‘heat produced’
do not allow energy produced / made
do not allow energy for respiration
allow sweating stops / reduces
ignore hair erection

1
[6]
Section 7
(a)  pituitary
1
(b)  ADH
1
(c)
high(er) concentration of blood causes (more) ADH / hormone release
allow low(er) water potential of blood causes (more) ADH / hormone release
allow alternative descriptions in terms of – eg low(er) water concentration / level or high(er) osmotic pressure or high(er) solute concentration / level
1
(and hormone / ADH causes) increased permeability of kidney tubules (to water)
allow increased permeability of collecting duct / distal convoluted tubule
1
(so) increased water reabsorption
allow more water taken back into blood
ignore reference to urine
1
(d)
allow converse if clearly describing dialysis
explanation must match reason
changes in concentrations / levels of substances / urea are minimised
allow no change in concentration / level of substances / urea
allow correctly named substances
1
(so) less / no chance of causing damage to body cells / tissues
allow eg less / no osmotic stress or not poisoned by urea
1
not repeatedly puncturing skin or blood not in contact with machine
allow blood does not leave the body
1
(so) less / no chance of infection or less / no chance of blood clots or no need to take anti-clotting drugs
allow less / no chance of microorganisms entering body
allow only one operation so less chance of infection for 2 marks
allow dialysis requires anti-clotting drugs and so may lose more blood if cut for 2 marks
1
Section 8
(a)    auxin
accept other correctly named plant hormones
1
Section 9
(b)     (i)      any three from:
•        no (fusion of) gametes / fertilisation
allow no meiosis or new cells only produced by mitosis
•        only one parent
allow not two parents
•        no mixing of genetic material
•        no genetic variation or genetically identical offspring
allow clones
3
Section 10
(a)  many (joined) nucleotides or monomers
allow (long) molecule / chain made of repeating units
1
(b)  phosphate
1
(phosphate attached to a) sugar
1
(which has 1 of 4) base(s) (attached to sugar)
ignore phosphorus
allow deoxyribose / pentose
allow 2 marks if position of sugar / phosphate / base is incorrect
1
(bases) are A, C, G and T
allow bases are adenine, cytosine, guanine and thymine do not accept thiamine / adenosine
allow description of a pair of nucleotides
1

(d)  (non-coding parts) can switch genes on / off
1

Section 11
(1)  Level 3: Relevant points (reasons/causes) are identified, given in detail and logically linked to form a clear account.
5−6
Level 2: Relevant points (reasons/causes) are identified, and there are attempts at logical linking. The resulting account is not fully clear.
3−4
Level 1: Points are identified and stated simply, but their relevance is not clear and there is no attempt at logical linking. 
1−2
No relevant content 
0
Indicative content
•   mutation (in gene / DNA)
•   randomly or due to chance
•   causes new / different protein / (visual) pigment to be made
•   in the retina of bird
•   (so more) variation in the wavelengths of light birds retinas could detect
•   birds with the mutation or birds able to detect UV are more likely to see fruits (that reflect UV)
•   birds with the mutation or birds able to detect UV are more likely to see where small mammals are or have been
•   therefore get more food (small mammals or fruit)
•   avoid being eaten (by small mammals)
•   out competing those birds without the mutation or birds not able to detect UV
•   so more likely to survive and reproduce or have offspring
•   by natural selection
•   passing on allele / gene / mutation to offspring
•   repeated over many generations
For Level 3 a link to UV vision is required
[14]
(b)     any two from:
•        most people still believed that God made all the animals / plants on Earth
allow against their ‘religion’
•        insufficient evidence
do not allow no proof / evidence
ignore ‘fossil’
•        the mechanism of inheritance / genes unknown (at the time)
2
(b)     any four from:

Section 12
(a)  from light / sunlight
ignore sun unqualified
1
absorbed by chlorophyll / chloroplasts
if no other mark awarded allow by photosynthesis for 1 mark
1
(b)  krill / herring / copepod
1
(c)  algae
1
(d)  1 algae
2 krill or copepod
3 squid
4 mackerel
(5 Human)
all correct for 1 mark
1
(e)  any two from: (losses due to)
•   non-eaten parts (of squid / krill)
allow bones / shells
allow eaten by other animals
•   respiration or respiring (in mackerel)
do not accept respiration produces / makes / creates energy
•   excretion (by mackerel)
allow loss of a named waste product such as CO2 / urea
ignore loss of waste unqualified
ignore faeces

Section 13

(f)  2.3 and 0.1 (million)
allow in the range 2.25 to 2.3 for 2.3 (million)
1

1
95.65217.....
allow answer from correct substitution of incorrect values from Figure 3
1
96
allow student’s calculated answer correctly rounded to the nearest whole number
1

(g)  Level 3: A judgement, strongly linked and logically supported by a sufficient range of correct reasons, is given.
5−6
Level 2: Some logically linked reasons are given. There may also be a simple judgement.
3−4
Level 1: Relevant points are made. They are not logically linked. 1–2
1−2
No relevant content
0
Indicative content
figures may be given without units (million tonnes) throughout
points for:
•   small fish are not caught so can live long enough to reproduce
•   biomass / stocks have generally increased after these laws introduced
•   ’77-’81 law (total ban) resulted in increase in biomass, eg 0.1 to 0.48 or to 0.9 by ’84
•   ’84 law (mesh size) resulted in increase in biomass, eg 0.9 to 1.8 (by ’90)
•   ’97 law (quotas) resulted in increase, eg 1.15 to 1.25
•   ’98 law (ban in breeding season) resulted in increase, eg 1.25 to 2.5
points against:
•   could be a cause other than the law or correlation does not necessarily indicate causal relationship or other factors
•   laws superimposed so can’t necessarily tell the effect of each
•   each law results in an increase followed by a decrease
•   quotas lead to dead fish being thrown back into sea
For Level 3 points both for and against must be considered together with appropriate use of data