0610 w13 ms_32

CAMBRIDGE INTERNATIONAL EXAMINATIONS
International General Certificate of Secondary Education
MARK SCHEME for the October/November 2013 series
0610 BIOLOGY
0610/32 Paper 3 (Extended Theory), maximum raw mark 80
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of
the examination. It shows the basis on which Examiners were instructed to award marks. It does not
indicate the details of the discussions that took place at an Examiners’ meeting before marking began,
which would have considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner
Report for Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2013 series for most IGCSE,
GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level
components.

Mark Scheme Syllabus Paper
IGCSE – October/November 2013 0610 32
© Cambridge International Examinations 2013
Mark schemes will use these abbreviations
• ; separates marking points
• / alternatives
• R reject
• A accept (for answers correctly cued by the question)
• I ignore as irrelevant
• ecf error carried forward
• AW alternative wording (where responses vary more than usual)
• AVP alternative valid point
• ORA or reverse argument
• underline actual word given must be used by candidate (grammatical variants excepted)
• ( ) the word / phrase in brackets is not required but sets the context
• max indicates the maximum number of marks

Question Expected answers Mark Additional Guidance
1 (a) unsegmented ; A no segments
soft bodies ;
(muscular) foot ; ignore feet
mantle ;
visceral mass ;
AVP ;
[max 2]
ignore
no (exo)skeleton
no backbone
no bones
radula
bilaterally symmetrical
shell / exoskeleton
(b) (8) legs / tentacles / arms / limbs / AW ;
(large) eye ;
has a head ;
no shell / (completely) soft body / no exoskeleton / no external
skeleton ;
suckers (on tentacles) ; [max 2]
R any internal features (see the question)
R feelers / hands
ignore no (muscular) foot / feet
A suction pads
(c) look for an adaptation for attachment and an adaptation for survival
when exposed to air
allow ecf from part (a)
attachment
threads / (muscular) foot / sticky fluid ;
survival in the air
either
shell / exoskeleton, prevents / reduces, water loss /
or
shell / exoskeleton, protects against (named) predator(s) ;
[max 2]
A any suitable description of the threads
e.g. fibres, projections, extensions,
tentacles, etc.
R suckers
A slime / mucus for sticky fluid
ignore protection unqualified
ignore anything to do with gas exchange
ignore camouflage
if named must not be an aquatic predator

(d) 1
2
3
4
5
6
7
has no, competitor(s) / predators (therefore increase in numbers) ;
has no, pathogens / parasites / disease-causing organism(s) ;
competes with existing species for, food/nutrients/space/oxygen ;
could be a, predator / consumer , of other species ;
A feeds on (many) other species
could introduce, disease / parasite, for native species
cause migration of native species ;
AVP ; e.g. reduces biodiversity
causes extinction
decrease in numbers, higher in food web / at higher
trophic levels
increase in predators of zebra mussels [max 3]
(e) 1
2
3
4
5
6
do not move about / stay in one place, so exposed to pollutant
(continuously) ;
pollutant, kills them / reduces their numbers / prevents them breeding
;
so presence / absence, is a good indicator ;
pollutant accumulates (in animal’s body) ;
pollutant, detectable when concentrations are low / no longer present
;
AVP ; they are filter feeders
do not need to know what the pollutant is (as would be the case for a
chemical test)
no need for lab facilities / no need for equipment / can be done in
the field [max 2]
R more accurate
ignore
easy to, see / collect ;
quicker to do
skills / training needed / cheaper

(f)
1
2
3
4
5
6
7
8
9
non-biodegradable plastics
swallowed / ingested / eaten / cannot be digested ;
caught around / trapped / entangled ;
choke / blocks gut / smother / suffocate / injure / cut / trap / stuck in /
AW ;
plastic blocks light for photosynthesis ;
may, contain / release, (oil-soluble) toxins / poisons ;
large pieces of plastic may block flow of water (in a river) ;
that reduce concentration of dissolved oxygen ;
effect of loss of organism at a trophic level ;
AVP ; e.g. any other consequence for organisms [max 3]
ignore kills / dies unqualified
A organism is poisoned (by toxins)
R ‘plastics are toxic’
A suffocate in MP3 as a consequence of
MP4
MP6 and MP7 are linked

2 (a) (i)
stimulus
(blue) light / (change in) light
intensity / dim to bright light ;
receptor cells
cones / rods ;
effector
(circular) muscle, of / in, iris ;
response
pupil, gets smaller / constricts /
AW ;
[4]
ignore retina (as it is a tissue)
R ciliary muscle
R radial muscle
R muscle / pupil, contracts
ignore muscle contraction
(ii)
1
2
3
4
5
if marked in the context of accommodation or a mixture of the two
reflexes, then mark to max 3
(nervous / electrical) impulses ;
sent by / initiated by, (named) receptors / sensory cells / retina ;
R if optic nerve, sends / initiates / AW, the impulse
via / along / through, sensory neurone(s) / optic nerve
to, brain / CNS / grey matter ; ignore spinal cord
(from the brain) via / along / through, motor neurone (to effector) ;
[max 4]
MP1 – M5 ignore ‘signals’ / ‘messages’ /
AW
ignore relay / connector / inter-, neurone ;
ignore ‘impulses to brain’ after the
response has happened

(b) 1
2
3
4
5
6
7
8
9
10
11
12
13
14
increase in, heart / pulse, rate ;
increase in, breathing rate / depth of breathing ;
more oxygen, taken in / absorbed ; linked to MP2
for (increase rate of) aerobic respiration ;
more energy released ; R energy produced
vasodilation in / arteries widen in / more blood to, muscle / brain ;
more oxygen to muscles ; linked to MP1 or MP6
vasoconstriction in / less blood to, gut / skin ;
stimulates, breakdown / conversion, of glycogen to glucose in liver ;
increases glucose (concentration) in the blood ;
dilates pupils ;
lets more light into eye ;
heightened sensitivity / increased mental awareness / AW ;
AVP ; e.g. increased width of (named) airways, increase in blood
pressure [max 5]
R ‘lots of heart beats’ unqualified /
increases heart beat
MP3 accept oxygen taken in faster
MP4 ignore metabolic rate increases
MP6 accept faster blood supply to muscle
MP7 accept faster supply of oxygen to
muscle
MP8 accept slower blood supply to gut /
skin
MP9 ignore glycogen to glucose in
muscle
MP10 does not have to be linked to MP9
MP13 R ‘excited’
(c)
1
2
3
4
5
6
7
assume answers are about involuntary unless told otherwise
automatic / no conscious decision / does not involve thought / involves
decision making ;
higher centres / AW, of brain not involved ;
faster / immediate ;
response always the same ;
involves, one / small number of, muscle(s) ;
may involve glands ;
they are protective / AW ; [max 2]
ignore voluntary / involuntary responses
can / cannot be controlled unqualified

3 (a) (i) 1
2
3
4
5
6
7
kills, / destroys, (all) bacteria / microorganisms ; A viruses
to prevent
contamination / remove contaminants (of the milk / yoghurt) ;
competition with the two bacteria added ;
disease / might be pathogens / any suitable e.g. (TB / food
poisoning) ;
production of toxins ;
alteration of the, flavour / taste ;
AVP ;
ignore ‘remove’ / ‘gets rid of’ / ‘eliminates’
ignore ‘harmful’
ignore impurities / make milk pure
kills harmful bacteria = 1 mark
kills bacteria that cause disease = 2 marks
kills bacteria that might contaminate the milk
= 2 marks
(ii) 1
2
3
4
5
6
7
best / optimum / ideal, temperature ;
for bacterial, growth / division / reproduction ;
A bacteria grow quickly
ref to enzymes ; R if enzymes are denatured at 45 o
C
ref to, kinetic energy / collisions ;
produce most lactic acid in the shortest time ;
A ‘lactic acid production takes too long at lower temperatures‘
ref to cost ;
bacteria killed / enzymes denatured, at higher temperatures /
[max 2]
R ‘speeds up the reaction’ unqualified
A enzymes are not denatured / bacteria are
not killed, at this temperature

(iii) 1
2
3
4
5
6
7
8
9
lag phase / numbers increase slowly / low rate of growth ;
ignore ‘numbers stay the same’
(while) bacteria, make proteins / increase in size ;
log phase / exponential phase / numbers increase quickly ;
A rapid rate of growth / bacteria divide faster than die
plenty of, food / nutrients / oxygen ; ignore raw materials
stationary phase / numbers stay constant ;
A ‘birth’ rate = death rate
death phase / increase in death rate / decrease in numbers / bacteria be
(because of) lack of, food/nutrients/oxygen or decrease in pH / accumu
ref to limiting factors ;
AVP ; e.g. Lactobacillus bulgaricus increases first [max 5]
accept (cell) division / (binary) fission /
reproduction for growth for MP1 and MP3
MP4 A ‘availability of food / AW’
(iv) 1
2
3
4
5
6
7
need different bacteria to, carry out different processes / produce
idea that each bacterium needs something produced by the other ;
Streptococcus (thermophilus) does not make lactic acid ;
Lactobacillus (bulgaricus) needs formic acid produced by
each stage requires a different (specific) enzyme ;
A enzymes work on different substrates
idea that each bacterium cannot make all the enzymes needed ;
AVP ;
[max 2]
A both needed to make lactic acid
A ‘work differently’
If MP4 awarded then also award MP2
A S. thermophilus
A L. bulgaricus

(b) preservative / acidity regulator / pH regulator ;
antioxidant ;
colouring / food dye ;
flavouring ;
emulsifier ;
sweetener ;
thickener ;
stabiliser ;
[max 3]
ignore
names and/or (E)
numbers of additives
e.g. MSG, tartrazine,
sunset yellow, etc.
Reject
fruit
chocolate
nutrients
any named
nutrient, e.g.
food starch /
corn starch
(named)
vitamin(s)
(named)
mineral(s)
salt
calcium
supplement

4 (a)
pea plant D E
substance
transported
sucrose phosphate ions
transport
tissue
phloem ; xylem ;
sink growing tip / flower /
fruit / seed / stem /
root ;
growing tip / flower /
fruit / seed / stem /
leaves / chloroplasts ;
[4]
ignore any vessels / tubes / etc
A growing point / meristems / areas where
growth occurs
(b) amino acids ;
R proteins [1]
A (named) plant hormones
(c) 1
2
3
4
5
photosynthesis ;
light (energy) is, absorbed / trapped, by chlorophyll ;
carbon dioxide reacts with water in the presence of light (energy) ;
to make glucose (and oxygen) ;
glucose used to make sucrose ; ignore fructose
[max 3]
A word equation / balanced equation if
MP3 not written out
do not award MP3 if ‘broken down’
A formula for glucose in an equation
MP5 do not award if glucose is broken
down unless already penalised in MP3
(d) 1
2
3
4
5
respired / oxidised to provide energy / used to provide energy /
energy for a suitable process ; R ‘produce energy’ A respiration
unqualified
converted to starch for (energy) storage ;
converted to cellulose to make cell walls ;
used to make nectar to attract, pollinators / AW ;
stored in fruits to attract animals (for seed dispersal) ; [max 2]
e.g. energy for, growth / active transport
R to make fruit / seed unqualified

(e) 1
2
3
4
5
6
root hairs / root hair cells ;
active transport ;
against, concentration / diffusion, gradient
A from low to high concentration ;
using, energy / ATP ; R energy produced / production of energy
from respiration ;
ref to, proteins / carrier molecules (in membranes) ; [max 3]
ignore diffusion / movement down a
concentration gradient / osmosis
ignore gradient in ‘from low concentration
gradient to high concentration gradient’

5 (a) halves the number of chromosomes / diploid to haploid ;
ignore halves the genetic material
produces variation / AW ; [2]
accept produces haploid, nuclei / cells /
gametes
ignore prevents doubling of chromosome
number
(b) (i) question is discounted [2]
(ii) 1
2
3
4
(only) one fertilisation / one zygote / one fertilised egg ;
zygote / fertilised egg / (cells in) embryo, divides / splits in two ;
by mitosis ;
into two (groups of) genetically identical cells ;
[2]
R ‘from a single cell’ but allow ecf for other
MPs
R egg divides
A same , genetic material / genetic make-
up / genome
R similar
(c) increase in, complexity / AW ;
ref to specialisation / differentiation ;
ref to different types of cells ;
ref to, tissues / organs ;
[max 2]
ignore (rapid) growth / change in shape
A ‘legs / arms / AW, start to grow’
(d) 1. Xh
Y ;
2. XH
Xh
;
3. XH
XH
;
[3]
do not accept male genotypes for MP2
and MP3

(e) 1
2
3
4
5
6
mutation / change in DNA ;
in the gene, for blood clotting protein / on X chromosome ;
in the mother / mother is a carrier / mother is heterozygous ;
R parent(s) is / are heterozygous
haemophilia is sex linked / shows sex linkage ;
idea that the mother’s egg with the mutant allele fuses with a Y
bearing sperm ;
e.g. cause of mutation ; ionising radiation / chemical(s)
[max 2]
MP2 can only be awarded if MP1 is
awarded
MP3 A in context of allele passing down the
female line for several / many generations
(without being expressed in a male)
ignore carried on the X chromosome as this
is in the question

6 (a) there are different forms of one, feature / characteristic ;
example of a feature shown by Soay sheep ;
coat / fur, colours
patterns of coat / AW
with and without horns
lengths of horns
ear, length / width / size / shape
face, length / width / size / shape
body mass
body shape / body size / AW [2]
look for a general explanation of
‘variation in their phenotype’ and an
example
the example chosen does not have to
be visible in Fig. 6.1
(b) (i)
1
2
3
in years with high populations of sheep
more deaths in total ; A low survival rate
for all sizes of lambs
more lambs died than survived ;
any comparative data quote using same body mass in high and low
population years – units (kg) are not necessary
A tolerance given in table for bars between gridlines
[max 2]
looking at sum total of the bars in each
graph
looking at bars for each body mass
e.g. lambs 13-14 (kg), 106 died in high
population year against 12 that died in
low population year
see page 18 for table of data

(ii)
1
2
3
4
5
6
7
8
9
10
in high population – ora for low population
one mark for competition and two marks for marking points 2-11
competition for, shelter / food / grass / resources ;
as a result of competition there is shortage of food for each lamb ;
as a result of competition for food
lambs do not store enough fat ;
ref insulation ;
cannot survive the winter ;
ewes / females, produce less milk ;
ref to number of lambs per female ;
ref to, more likely to die of disease / AW ;
A disease more likely to spread
more small lambs die ;
(pregnant) ewes / females, are short of food
[1]
[max 2]
ignore explanations about why the
population is high in some years and
low in others – not relevant
R competition for mates

(c)
1
2
3
4
5
6
8
note that this is not a question about artificial selection
variation / AW, among the sheep in the population ;
some are better, adapted / suited / AW, than others ; A ‘best adapted’
any example of an adaptive feature for survival in the extreme conditions ;
any example of an appropriate selective agent ;
ignore ‘extreme conditions / weather’
survive and, breed / have offspring ; A ora
pass on their alleles ;
idea that
over time better adapted, features / traits, become more common ; [max 4]
points need to be in correct sequence
and in the context of selection
R better animals survive unqualified by
adaptation or some example
‘some sheep have thicker coats’ = MP1
and MP3
MP3 must be a feature related to
survival in extreme conditions, not
‘strength’, ‘fitness’ ‘healthiness’ etc
to survive the cold = MP4

body mass / kg low population years high population years
died survived died survived
3 – 4 0 0 6
(5 – 7)
0
5 – 6 0 2
(1 – 3)
15
(14 – 16)
0
7 – 8 0 7
(6 – 8)
20 3
(2 – 4)
9 – 10 5
(4 – 6)
16
(15 – 17)
56 6
(5 – 7)
11 – 12 12
(11 – 12)
48 94
(93 – 95)
25
(24 – 26)
13 – 14 12
(11 – 12)
57
(56 – 58)
106
(105 – 107)
30
(29 – 31)
15 - 16 12
(11 – 12)
52 48 34
(33 – 35)
17 – 18 6
(5 – 7)
22
(21 – 23)
16 18
(17 – 19)
19 – 20 2
(1 – 3)
12 6
(5 – 7)
2
(1 – 3)
21 - 22 0 0 2
(1 – 3)
0

0610 w13 ms_32

More Related Content

Similar to 0610 w13 ms_32

More from King Ali

Recently uploaded

In this document

0610 w13 ms_32