o22O7O2O
CARIBBEAN
EXAMINATIONS
COUNCIL
CARIBBEAN ADVANCED PROFICIENCY EXAMINATION@
B
IOLOGY
UNIT 2
PAPER 02
MARK SCHEME
MAY,/JUNE
2
015
/c?PE/Mn 2015
-2-
o22A'7 020 / CAPE / MS 201s
Biology
Unit 2 Paper
02
Mark Scheme
,June
Question
(a) (r)
2
015
1
A reqion: Increase i-n photosynthesls rate directly
(linear)to increase in light intenslty
propoltional
B region: no change in photosynthesis rate as light intensity
increases/no further effect of light on rate/rate remains constant
Each d€6cEiption
(ii)
Oxyqen production
[2 Earks]
1 Eark
in p hotosvnthesis
. Light energy causes electrons to be emitted from PsII
(Photosystem II)
. Electrons return to PSII flom !.,ater, refeasing 02
. Photolysr-s -enzyme (in PSII) splits water
. 21za - 4H* + 4e- a O: I must state 02 release and at least
other product of photolysis, hydrogen or electrons)
2- 4 points
1 point
(b)
(i)
crpillarr tub€
m.t3urlne Or
2 uarke
1 nark
one
[2 Earke]
stlIched graph p.Pcr
or rul€r mersurcmcol
Stringe to re$l
sodr lime for
.brorbing CO)
gcrminr.ing
mcnLrcuYholdine bcrar
l,ocation for pfacement of germinatlng seeds
Carbon dioxlde absorbent (soda lime)
System for measurement of O: uptake (e.g. capiLlary tube and
meniscus with graph paper background)
Colrect diagra-E with all colrponentg
(capr-I1ary tube, syringe, soda lime and seeds)
1 Ealk
correcb
ttrre€
least
with
at
diagraE
Representative
3 marks
annotations
2 Balka
Wi.th 2 annotations and other Lab61s
1 Eark
tlith colEect labels and/or one annotation
Procedure:
Pface lrelghed seeds in respironeter
ColoLrred waLer dropfet inLrodrced lnio capillary tube by drPP:- ng
t1p into beaker of r.rater
r'o
Movement of meniscus of coloureo wal-er drop measured ovel time
calculaLe vcLur,e oi C uP'.ake
Conplete descriPtion
2
maEks
[6 narks
]
-3Biology
Unit 2
Paper 02
Mark scheme
June 2 015
1 Dark
Partial description
o22A'7 A2A / CAPE/ MS 2015
-4-
Question 1 cont'
(ii )
Biofogy
Unit 2 Paper
Mark Scheme
June 2 015
a2201 020 /3APE/ MS 2015
02
d
Precautions
1
2
3
4
Handle soda lime (CO2 absolbent) with care
Ensure apparatus / se t -up is a1rtight
Ensure that no air bubbles in capillary tube with indicator
fluid
Do not handfe respirometer once it
is set up (place at
constant temPerature
Allow apparatus / set-up to equilibrate for a few minutes
Take measulements when !ate of movernent of meniscus is
)
5
6
constant
Return droplet to end of tube by pushinq in the syrinqe
plunger
B
Use fresh, health seeds/do not leave the gernlnating seeds
too -Long (e.9. days)in Lhe syrjnge
Germinating seeds should not touch soda lime
10. Remove testa from seeds
1
11.
Set up a contlol respirometer with inert material instead of
germi;ating seeds to account for any changes in atmospheric
condit ions
72. Do repl ications
13. Any other Plausibl-e Precarr Li on
For each of any 5 Poi.nts - 1 Dalk
[5
Barks I
Total 15 EarkE
Biology
Ut,it 2 Paper
Mark scheme
a22At 020 / CAPE/ MS 2 015
02
June 2 015
Question
(a)
(i)
(ii)
2
Arlow pointing to rubber bung in vertical
capillary tube on Figure 2.
reqion ot
[1
Bark I
Basis: as water absarbed fron capiflary tube ta fiaintain the
transpiration strean, air bubble noves fton oae point to another
a)-onq capifTary tube
tlavelled by the bubble in a given time interval
using the scale/r€cord tiEe taken for bubble to travel along a
specified dis tance
R€ading i9 taken s€v€raL times during the duration of the
M€asure distance
experiment
Av€rage r€ading is cal culated
R,ate of tranEPiratj'on
travelled Per unit time
3-{ points
2 points
1 point
(b)
is
calculated
3 Darkg
2 narks
1 t[ark
from average distance
[3 rarks l
xyfem vessel
1
2
3
4
5
6
1
B
9
of water
Tlssue consists malnIy of (thln) vessefs conduct a stream
inuous
Vessels tong (elongated) and arranged end to-end form a cont
column
no barrier to
End vrall-s of cetls with perforatlons (br'oken down)
flow
water rises
Narrow lumen (i-n some specles) increases hej-ght that
Wlde lumen (in some specles) minimizes resistance to flow
cell contents)
Vessels aie holIow(empty lumen/no cytoplasm/lack
transport of
raprd
for
allowing
fIow,
reduces resistance to water
water
to r'ralf s and
Vessel walL ce 1Iul-ose -hydroph i L ic-wate r molecufes adhere
supPort column of vJater
fo' support (Less
CeLl of vessel walIs -Lignifred makes it rigid
loss
likely to collapse unaer iater tension)/wal1s leaterproof hence
of water mlnimi zed
Pits present in xyLem vessel walLs
vessels/overcome aI} a ir lock
aLlow movement between xyLem
-6a220102A /
CF,PE /
MS 2015
Bioloqy
Uoit 2
Paper
Mark Scheme
June 2 015
Question 2 :..: ' I
10.
11.
72.
02
by
s (of mature xylem tissue)are dead hence all water absorbed
by
used
being
without
root hai r cells gea transported to the leaves
passive
a
mostly
is
Process
the cel1s of xylem ta s sue / transport
Pre s ence of tracheids in xylem tissue - conduct water
Presence of parench\rma celfs - buffer for water transport
[4 Barksl
1 nark
FoE each of anY four PointE
Cef
l-
(c)
lodm. -1
Intim.
(litrin8
E.dir
morcl.
[b].
- .b.tic llDrt
-l'
(c)(a)
endothe.l i um (part of tunica
Cells/nuclei shown on i nnermos L Iayer
int rma )
thick wavy lines (part
Layer of eLastic fibres beneath endotheliun
of Eunica 1ni ama )
smooth
lines
Middle Iayer (tunaca medla) !J1th dense fibres/thacker
muscle/eIastlc t as sue
loose fibres/finer llnes (less
outer laYer ( tunica adventitia )
connective tissue
dense )
1 Dark [4 Earkg]
For each tissue laYer - detailE dralrn coErectLy but detaifs are
Nate: If there is an atterlpt to dtaw details
award 7 nark.
layers
tissue
incorrect foi at Least three
-1a2201020 /:APE/ MS 2 015
Biology
Unit 2 Paper
Mark Scheme
02
,fune 2 015
Question 2 .cnl 'C
(ii)
. Very thick walls
. Made up of smooth muscle and efastic fibres
. Aflows wall to stretch under pressure (do not burst or
rupture )
. Convoluted nature of endothelium allot s lumen to
expand
Each of any two Pointg
(iii)
Di
1 Eark
[2 Eark6l
fference
Larger/wider lumen
Thlnner walls
. Walls are collapsible
change s (irregular
Anypoint-1lark
shape of lumen
)
[1 Dark]
Total 15 Earke
-8Biology
Unl.t 2 Paper
Mark Scheme
0220t 020 /CAPL/ MS 2015
02
,fune 2 015
ouestion
(a)
3
(i)
20
l6
Age group
2
D2-5 ye.rcld
D
EGll
8
ye.r-old
Nll2-19 yerr-olds
4
0
tg7t-1974 1976.1980 198&194
2003-21)06
Time Perlod
Bars clearly distinguished,/key given
A11 data points correct
Appropriate scale used (at least % paqe used on boLh
axes )
Bais separa*.ed betlreen time int€r'vals
Axis lntervals correctly label led
Axls-titles correc t
. Appropriate graph title given ( see Table title for
example
)
6 - 7 points
5 pointa
4 pointg
3 points
2 po j,ntg
5 EarkE
4 BarkE
3 Darks
2 narks
1 nark
Note.'
If line graph drawn award I nark if titfe given
If bar gtaph dtawn as stacked bar chart accepL if
points plotted co r tect fY
(rr)
Chanqes
[5 narks]
in obesrty
GeneraL increase in obesity +evels over time for al aqe g roups
The degree of increase in obesaty levels over time 1s smal I es t
for the 2-5 years age group/more marked for oLde' age group s
1
Accept any othe! aPProPriate deEcription
Each poj.nt - 1 mark
[2 narks
]
-9-
02201020 / CAPE/ MS 2015
Bi ol ogy
Unit 2
Paper
Mark Scheme
June 2 015
Question 3 ccni'
(iii )
d
Reasons
.
.
.
.
02
for trends
Lower 1eve1s of physical activity (exercise)
Poor diet and eatinq hab.rts
Lifestyle changes related especially for the older age groups
surveyed \6-7f, 12-19 years o1d) increased time spent on
electronic devices ?
Any othe! plausible reason e.g. socio-economic, cuftural, lack
of awareness of nature of condition
[3 aarks]
Eachpoint-1Eark
(b)
(i)
De
.
.
scrip! ion of
respon se
Short delay (2-3 days) no production
Then rapid increase in antibody concentration in the blood
after infecti on
. Maximum levels in blood at 10-14 days after infection
. Then level begins to fall slowly
3-4 pointE
1-2 points
(ii)
2 Darkg
1 Eark
t2 earks I
Secondary response memory ceffs from an earlier exposure
pathogen wilI allol'r rapid prodLlcLion of antibodies. 1 DaEk
to the
[1 narkl
(c)
antib odv
Active: immune svstern st imul a ted to produce part icular
ion
nat
vaccl
or
i-nfection
previous
(and can do so rapidfy) bY
Provided
Passive: InununitY Provided bY antibodies or antitoxins
e'g
fr:om outside body (natural e.g rnother to baby, artaficial
rnjection)
EachPoint-1rark
[2 Darks]
Aotal 15 Earks
-10a220'7A20 /CAPE/ MS 2015
Biology
Unit 2 Paper
02
Mark Scheme
June 2 015
Question 4
(a)
(i)
Explanation of i ne f ficiency
Energy transf€r froE one troPhic level to anoth€r is only 10
per cent or even leEs/ on average about 10 per cent of net
energy production at one trophic levef is passed on to the next
level/as enerqy passes along food chain lalge loasoa occur at
each t:rans f er
For example sun to plants 1s only 1 per cent efficient/
transfer of that energy from plants to primary consrlmers is 108
of energy from prj'mary consumers to
e ffi-cient / trans fer
secondary consumers is broken down to another 10 per cent and
so on/food chain can sustain no more than 6 levels due to
ine fficiency/organi sms high up in the food chain qet very
1itt1e of original energy input.
Trop hic level definition
group of organism occuplaing t}€ sa.De feeding Poaition in food
chain (e.g. PrimarY Producels, prrmary constuterS, secondarY
consumers / feeding fevel
Reasons
5
Of all sunllght available only smaff per cent converted
green pl-ants to chemical energy (Iess than 3 per cent )
Some
of the organisms die and are not eaten
bY
hence energY
foss
Some parts of
faeces /wa s te
organisms not digested and so energy lost
Some
energy is lost as nitrogenous excretory materials
Some
energy is lost as heat in resplration/digestron
as
energy used for growth, repair: and reproduction hence not
passed on
Some
Nutritlonal qualrty of matertal that is consumed - consume r s
can convert high-qualiLy food soulces intc new fiving tissue
than low-quallty food s oulce 5
more efficiently
Elq)lanation of inefficienqY - 2 earkg
1 nalk
IncotoPfete D€finj-tion of tloPhic level - 1 Dark
1 nark
Each of any Chree reasons
[6 narks
]
-11Bioloqy
Unit 2 Paper
Mark Scheme
June 2 015
a2201020 /3APE/ MS 2015
02
Question 4 ccri'd
(relatlve) nurnlcer (amount) of
(ii ) Pyramid of !!@eI!
indivj-dua1s/orqanisms (per unit area) at each trophic (feeding)
level
Pyramid of Biomass - vreight (total, dry) of organisms at each
trophic level (at partj-cular time )
(productivi ty)
amount of enelgy (cal oric
P ramid of Ener
value/productj-vi ty ) at each trophic leve1.
Pyramid
of energy most accurate representatlon
because
No inverted pyramids are obtained (as seen in aquatic
bi
.
.
.
.
omas s
)
actuaf energy transferred and includes solar eoergy
input
Can be more readily used to compare ecosystems/two species
at the same leve 1
Can measure productivity over tlme (not static/or limited
to one point in time as other t!.ro/not standing crop)
Overcomes dj.fficulty and complexity of collectlng (huge)
data for pyramid of nurrbers Shows
. Difficulty in assigning specles to tiophic levels for
quantlfrcation (nunbers or biomas s )
. Can take into account juveniles or 1[unature folms
. More useful to compare relati-ve energy flows in different
ecosystems/two species at the same trophlc leveI
Each of three PYraoids - 1 Dalk
S61€cting PyraEid of energy as DosC accurate
Any one reason - 1 Eark
Note: Award 7 nark lf aLL three types af pyranids
stated but not
(b)
1
desc r Tbed
1 Dark
[5
Barks I
biodiversj.ty promotes stabil ityl ecos ys tems with compfex food
webs (high biodiversity) more stable/Loss of blodiversity (number
of species) causes a loss of ecosystem stability/increased
compfexity is usually associated r'rith greater stabll1ty
Hj.gh
study of grassland in USA
one ecologicaf field
richness also fowered the
plant
species
reductions in
resistance of grassland productron to drought
-72a2201020 / ]APE/ MS 2015
Biofogy
Unit 2 Paper
Mark Scheme
June 2 015
estion
'j
b c.iii
4
02
Grazing ecosysLem in Serengeti
to stability
high biodiversity
linked
Paine sLudied the animal-s that Iive alongr a stretch of
rocky seashore by removing one pr:edatory sea star species
after a trme, blodiversity decreased greatly stability no
longer exi st ed
Studies of microbiaf corurunities in snall experimental
charnlrers show that fluctuations in ecosystem functions such
as producti-vity can be greater when species richness rs
reduced
OR
2
Divereity tends to de-stabilize coErDunity dynBDics,/ high
baodrversity may not promote stabrlity
Many object to modeling
multispecres lab corununities
lntroduced species can
pests on continents
crash
become
Naturaf monocultures (salt marsh, bracken)
lnsect
abundance
seem
stable
does fluctuate markedly in
troprcal
OR
3
Debate as to whether relationship beeween diversity and stabiLity
(e . g ,
is sinp]-e ay b€ aultiple
impact more
r€l,ationships
pronounced at lower 1eve1s of diversity cf to hrgher or dependent
on leve1 at vrhich stabillty
1s berng defrned ecosystem versus
spec ie
s
)
Experiments in aquat i c ecosystem large scafe proce
play a signi ficant rofe in determining ou tcome
s
se s
OR
4
shether coroplex ecosystems are ttlore or
Unable to say definitively
limited evidence for and against
less stable
Few experimental studres on
stability have been at tempt ed,
a long term at tribute of a
"eqJ''es ei!heL lo.lg-ru.lrjng
with short I ived organrsms
impact of biodiversity
on
mdinly because sLabifrry is
system and testing for it
experiments or experinent s
-13Bj.ology
Unit 2 Paper
Mark Scheme
June 2 015
a2201020 /3APE/ MS 2015
02
Questj-on 4 (b)ccni-''j
Experiments nanipulating divers i ty criticized because of
24-yeat study of I nner
small spatial and temporaf scales
Mongofia grassland shows vari at ion
Giving c19ar viellpoint wit}t €r<Planation
No €rq)lanation,/viewpoint not clearlY atat€d
Discussion of evidence in suPPort of viewpoint
Incorylete/validitY unclear
Nate: If specif ic,/h@othetical exanple given e.q
detorestation and inpact an associated fauna ot
fionflsh and caraf reefs - award 7 mark
-2 Darke
-1 Dark
-2 Darks
-1 Eark
[4 Darksl
Total 15 Darke
-14Biology
Unit 2 Paper
Mark Scheme
June 2 015
Question
(a)
02201A2A / CAPE / MS 2015
02
5
Absorption of glucose occurs in proximal convoluted tubule of
nephron
Active transport of Na* out of (proximal) tubule cells across outer
menbranes
Nat moves from glomerular fil-trate into tubule cells due to
concentration gradient
glucose co-transport s ystem (carrier) that transports glucose
Na
at the same time
For €ach any 3 Pointss - 1 Dark
is
Presence of gfucose in urlne can occur if concentration in blood
very hiqh
This may indicate diabetes but requires more tests to confirm
sefective re absotpxton
Accept: Impairnenx af kidney function
Clinical Sigrrificance well erPlained
IncoEplet€
2 Darke
1 tlark
[5
-(b)
EaEkEl
Initiatlon
Cycle i orti ated by SAN (sino-atrial
node) ln muscle of right
atrium.
Cy c1e
detai
Is
emits impul-ses that travel across cardiac muscle in
atria st imul ates atria to contract
impul se s
Electrical s igna ls move to AV Node det aying (emptY
inq) bLood into
forcing
AtriaI sys tole : Atrla cont ract
cl osed )
valves
open/semilunar
ventricles (AV vafves remain
to
Purkinj e flbres
HIS
then
of
bundle
Signals move from AV Node to
atlows ventricle to contracL
bLood out ot
Ventri cul ar systofe - both v.ont ri cle s contract forcingvalves forced
lunar
heart (lnto arteries) (AV valve s close / semi
open )
chanicers relax and fiLI with
At ri a] and venLllcLrlar diastole
blood
SAN
Mechan i sms
to prevent backflow
Valves in velns ( semi luna r )
Valves be tween airia and ventricLes
reverse bLcod flow
(tricuspld,
bicusPid) Preven
L
-15Biofogy
Unit 2 Paper
Mark Scheme
June 2 015
Ouestion 5 c.n
1,'
o22A'7 02A / C|\PE / MS 2015
02
i
1 Dark
Initiation
Any 3 pointE of qYcI€ &taile to include
at leaat on6 refer€nce to atrial and/or v€ntEicular
2 Darks
diastoLe & systol€
1 Ealk
IncoDptete (any 2 Points)
1 Bark
Arty one point for Backflow
(c)
Reg ulatory
effects of
[4 oarksl
Co2
in blood vessels (carotid arteries) monitor
concentration of Cor and other subsLances.
High CO2 leads to stimulation of sympathetic nerve (cardiac
Chemorecepto!s
tor )
Increased heart rate
acce 1e ra
For each Point
Adrena I
1 [ark
ine
stimulate
anticipation)
Impulses from braan (during nervous
glands
I
adrenaline Production bY adrena
in bloo d to heart and stimulates SAN
Adrenaline circulates
-(sino-atrial node)
Increases cardiac outPut
heart rate
force of contract ion
3 tr,oints
2 poinca
1 point
3 Darka
2 Earks
1 Eark
[6 Earks]
Total 15 Darks
-L6a220'7 020
/:APE/ MS 2015
Biofoqy
Unit2-Papei02
Mark Scheme
.lune 2 015
Questlon
(a)
(i )
6
Di sease
refer to a speci fic ilf ness,/bodily disorder due to a s ingle
cause (e.g, Pathogens)
Wider use - anything that impai rs normal functioning of
body/dlsordered state of an organ
May
Discussion
1
2
3
4
on (influencad by) social and econo[ic envilonEent likely
higher a personrs socioeconomic status is, the more
of
1eve1s
Iower
with
people
good
health/
enjoy
heishe) is to
education generally have a hlqhe! risk of experiencing Poorer
heal Lh/access to health serv.ices
Dep€ndent
what is
Dep€ndent on physical environDent (where we live'
safe' the air
physically around us) - if your water 'is clean. andyour
house is
heafthy'
you nreutn. is pure, your workplace is
heal-th'
good
to
enjoy
likely
more
comfortable and safe, you ale
and b€hawiors
D€p€odent on Pe.8on'B individual charact€ristics
job'
statistics
a
person
has
(who we are and what $,e do) - if a
people
healttFthan
better
enjoy
;how ,Ehat he (she) mcre likely to
N rKl'i
ll'e's
conlroL
some
have
rlnenp!at'ed/
r,riia .it:e
';e!
support,
conditions neaLtn witl benefit too/ tf one has famify
ot
chances
coinmunity
as support from friends and
." *"ff
none
who
has
somebody
greater
than
far
enjoying good health are
how a
a'n."i ini,,qsl traditions and customs of a societyin and
people's
role
"i.."porris to them play an lmportant
i.^iiy
drug use'
issues- diet, physlcal actlvity'
health/lifestyle
diseases
tiansmitted
sexuafly
e.g.
pithogens
exposure to
Biology and Genetics
Range of factors e.g' age- where ofder adults are bioloqrcally
due to the
proie to beang in poorer health than adolescenfs
qender
related
aging/sex
inv"L..L and cognitive effects eof
anaemla'
ce11
sickle
condations
'g'
?.lto."/inn.tit.a
haemophilia, family history of heart disease/ diabetes
Explanation of diseago
incoryIete
- 2 Earks
- 1 mark
- 2 Ealks
Any thrae factore gtated
1 nark
Onty ewo factors stated
2 q4!ks
gtated
factors
of
Discussion
Orrfy ot" factor gtated riiCh discusEion - 1 Bark
Stating three factors but discussl.ng one - 3 Earks
[
5 riarks
]
-1'7
-
Biology
Unit 2 Paper
o22A'7 02A / CAPE / MS 2015
02
Mark Scheme
.rune 2015
ouestion
6 cont ' d
(ii) Categorles
1
Social
2
3
4
human induced
or self-inflicted
Infoctious/coDDunicable/pathogenic
caused by
organisms or passed frorn one person to another
living
Deficiency - absence of nutrients in a diet
G€netic/congenital due to genetj-c defects or plesent at
birth
5
6
Ag€ing,/deg€nerativ€/chronic - associated with degeneration of
tissues
Mental variety of disorder associated with impairment ot
brain function/mind
acute'
nan- j:nfect iou s ,
le,
physical, physloloqicaf disease, fifestyfe but onfy if
there is no siqnificant overTap between twa cateqoraes
Accept:
norl-connunica
b
stated
Problem
rigid
Difficulty in assignrng a disease to single category/no
disease
of
aspects
fferent
di
/
of
categories
ap
bounda riei / overl
used
any aPpropri ate e . g. heart disease coufd be
Example
could
congenital or human induced or physical/mental allness
with
social
associated
disease
i
ous
fecL
in
if,ed/sone
inher
be
conditlons
EACH of anY tvro categories described
- 1 aark
no/incorrect
but
stating two categori6s
- 1 mark
descEiPtions
- l Eark
Stating ProbI€E
[4 Earksl
challenge
exanple tso desonstrate
- 1 Bark
(b)
sandra
Phygical deP€ndence (freqlleocy of use/strong craving)
Shows withdrawal s],mptoms (nausea, restiess and anxiolrs)
use of the drug is abruptfy reduced or stopped for short
period/s\,..nptoms severe based on frequency of use
rrhen
ti.me
-18a220'1020 / CAPE/ MS 2015
Biology
Unit2-Paper02
Mark Scheme
,fune 2 015
Question 6
con l
'C
l"Iayne
Psychological &p€ndence ( craving
)
Can qo without use for long periods/no stronqt withdrawalbored
or
depres sed
symptoms/i1lness/use when feeling
(mind) /share experlence trith friends
Expl anation
Druq abuse habltuaf (compulsive/excessive/self-damaging) use
of drugs to alter one's mood/ emot ion/ s tate of consciousnes s /use
of a drug for a non-therapeutic effect/use leading to an
addiction
(dependency)
- d€P€ndency correctly identified and 2 Earkg
corEectfy identified but not clearly justified - 1 Eark
Correct exPlanation of drug abuse - 1 Dark
Note: if dependency suqgested far both cases but twe nat
identified award ane nark
FoE each case
justified
[5 narksl
Total 15 [a!ks