specimen (ial) ms - unit 6 edexcel biology

Pearson Edexcel International Pearson Education Limited 2013 Sample Assessment Materials Advanced Level in Biology

233

Mark Scheme (SAM)

Pearson Edexcel International Advanced Level in Biology

Unit 6: Practical Biology and Investigative Skills

14

*S45359A01416*

(e) The limitations of your proposed method.(3)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(Total for Question 3 = 22 marks)

TOTAL FOR PAPER = 50 MARKS


234

All material in this publication is copyright Pearson Education Ltd 2013


235

General marking guidance

x All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last.

x Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions.

x Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie.

x There is no ceiling on achievement. All marks on the mark scheme should be used appropriately.

x All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidates response is not worthy of credit according to the mark scheme.

x Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited.

x When examiners are in doubt regarding the application of the mark scheme to a candidates response, the team leader must be consulted.

x Crossed-out work should be marked UNLESS the candidate has replaced it with an alternative response.

x Mark schemes will indicate within the table where, and which strands of Quality of Written Communication, are being assessed. The strands are as follows:

i. ensure that text is legible and that spelling, punctuation and grammar are accurate so that meaning is clear

ii. select and use a form and style of writing appropriate to purpose and to complex subject matter

iii. organise information clearly and coherently, using specialist vocabulary when appropriate.


236

Using the Mark Scheme

Examiners should NOT give credit for incorrect or inadequate answers, but allow candidates to be rewarded for answers showing correct application of principles and knowledge. Examiners should therefore read carefully and consider every response: even if it is not what is expected, it may still be creditworthy.

The mark scheme gives examiners: x an idea of the types of response expected x how individual marks are to be awarded x the total mark for each question x examples of responses that should NOT receive credit.

/ Means that the responses are alternatives and either answer should receive full credit.

() Means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of the expected answer.

Bold Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer.

ecf/TE/cq (error carried forward)(transfer error)(consequential) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part of the same question.

Candidates must make their meaning clear to the examiner to gain the mark. Do not give credit for correct words/phrases which are put together in a meaningless manner. Answers must be in the correct context.


237

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

1(a

) 1.

and

2. I

dea

of c

lear

dep

ende

nt v

aria

bles

, e.

g. t

idal

vo

lum

e, m

inut

e ve

ntila

tion,

bre

athi

ng r

ate,

rat

e of

ox

ygen

abs

orpt

ion

3.Ref

eren

ce t

o su

itabl

e un

its for

a c

hose

n de

pend

ent

variab

le

4.Id

ea o

f ca

libra

tion

of s

piro

met

er t

race

5.D

escr

iptio

n of

how

tra

ce u

sed

to o

btai

n de

pend

ent

variab

le

6.Id

ea o

f re

peat

s

ACCEP

T M

ps fro

m s

uita

bly

anno

tate

d di

agra

m,

e.g.

M

ps 1

, 2,

5.

Mp1

and

2.

NO

T d

epth

of

brea

thin

g,

tida

l int

ake

, vi

tal c

apac

ity,

IRV,

ERV.

Mp4

det

ail n

ot r

equi

red.

Mp5

som

e de

tail

requ

ired

, e.

g. c

ount

the

num

ber

of

peak

s pe

r m

inut

e.

ACCEP

T re

peat

in t

erm

s of

mea

sure

men

t of

an

indi

vidu

al o

r us

ing

seve

ral s

ubje

cts.

(4)

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

1(b

)(i)

Any

tw

o fr

om:

1.Sam

e pe

rson

2.Sam

e ag

e

3.Sam

e ge

nder

4.Te

mpe

ratu

re

5.Ti

me

of d

ay/e

q

6.D

iet

befo

re t

estin

g/eq

7.Spe

ed o

f ky

mog

raph

/eq

8.Any

oth

er c

redi

ble

alte

rnat

ive

vari

able

App

ly li

st p

rinc

iple

m

ark

first

tw

o va

riab

les

give

n.

Do

NO

T ac

cept

mas

s vo

lum

e of

sod

a lim

e KO

H

(sho

uld

be in

exc

ess)

, re

fere

nce

to o

xyge

n so

urce

or

oxyg

en c

once

ntra

tion/

leve

l in

spir

omet

er.

ACCEP

T si

ze/m

ass/

BM

I/ph

ysic

al a

ctiv

ity o

f su

bjec

t,

time

to a

cclim

atis

e, h

umid

ity.

(2)


238

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

1(b

)(ii

) 1.

App

ropr

iate

var

iabl

e ch

osen

fro

m 1

(b)(

i),

with

su

itabl

e co

ntro

l met

hod

desc

ribe

d

2.D

escr

iptio

n of

like

ly e

ffec

t on

the

dep

ende

nt

vari

able

pro

vide

d

Mar

ks c

an b

e aw

arde

d as

long

as

the

vari

able

cho

sen

was

sug

gest

ed in

1(b

)(i)

eve

n if

not

cred

it w

orth

y in

1(

b)(i

).

Mp1

ACCEP

T us

e a

tem

pera

ture

-con

trol

led

room

/roo

m t

herm

osta

t/ai

r-co

nditi

oned

roo

m/e

q.

NO

T ca

rry

out

at r

oom

tem

pera

ture

.

Sim

ilarly

with

tim

e t

hey

need

to

give

som

e de

tail,

e.

g. r

ecor

d br

eath

ing

for

5 m

inut

es/u

se a

sto

pwat

ch

to e

nsur

e br

eath

ing

was

rec

orde

d fo

r sa

me

leng

th o

f tim

e.

Whe

n de

scribi

ng t

he li

kely

eff

ect,

we

expe

ct t

o se

e a

reas

onab

le a

ttem

pt t

o de

scribe

effec

t of

cha

nge

in

cont

rol v

aria

ble

on d

epen

dent

var

iabl

e.

Do

NO

T ACCEP

T: g

ener

al s

tate

men

ts s

uch

as w

ould

gi

ve in

accu

rate

res

ults

Mp2

in c

onte

xt o

f th

is e

xper

imen

t in

crea

sed

envi

ronm

enta

l tem

pera

ture

will

lead

to

a re

duce

d br

eath

ing

rate

and

tid

al v

olum

e (c

onve

rse

for

decr

ease

d te

mpe

ratu

re).

At

high

er t

empe

ratu

res

the

brea

thin

g ra

te w

ould

de

crea

se g

ains

Mp2

.

(2)


239

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

1(c

)1.

Mor

e {e

nerg

y/re

spirat

ion/

oxyg

en/e

q}

need

ed/e

q

2.Ref

eren

ce {

auto

nom

ic/s

ympa

thet

ic

(inc

reas

es)/

para

sym

path

etic

(d

ecre

ases

)/so

mat

ic}

nerv

ous

syst

em/p

hren

ic

nerv

e/eq

3.Ref

eren

ce

{ven

tilat

ion/

resp

irat

ory/

insp

irat

ory/

expi

rato

ry}

cent

re

4.(I

n) m

edul

la

5.Id

ea o

f ch

emor

ecep

tors

(ca

rotid

/aor

tic)

6.Ref

eren

ce c

hang

es in

{ca

rbon

di

oxid

e/pH

/tem

pera

ture

} (i

n bl

ood)

det

ecte

d

7.Ref

eren

ce (

mot

or)

cort

ex

8.Id

ea t

hat

nerv

e im

puls

es g

o to

mus

cles

in

volv

ed in

bre

athi

ng

ACCEP

T co

nver

se if

it is

cle

ar t

he s

tude

nt is

ref

erri

ng

to ly

ing

dow

n.

IGN

ORE

nerv

e im

puls

es/n

ervo

us s

yste

m.

NO

T if

inco

rrec

tly q

ualif

ied.

ACCEP

T br

eath

ing

cont

rol c

entr

e.

Mus

t be

in c

onte

xt o

f co

ntro

lling

bre

athi

ng.

NO

T if

inco

rrec

tly q

ualif

ied

by lo

catio

n.

ACCEP

T ch

emor

ecep

tors

in a

rter

ies.

IG

NO

RE

stre

tch

rece

ptor

s.

(4)

Tota

l fo

r Q

ues

tio

n 1

= 1

2 M

arks


240

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

2(a

) 1.

(The

re w

ill b

e) n

o si

gnifi

cant

diff

eren

ce

2.In

the

num

ber

of w

orm

s {c

omin

g to

the

su

rfac

e in

eac

h 0.

5 m

2 {q

uadr

at/f

ound

/eq}

be

twee

n ea

ch {

plou

ghin

g te

chni

que/

field

/eq}

/eq

Diff

eren

t nu

mbe

r of

wor

ms

in t

he fie

lds

OR b

ecau

se

of d

iffer

ent

plou

ghin

g.

(2)

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

2(b

) 1.

(Med

ian

for)

fie

ld A

= 8

2.(M

edia

n fo

r) fie

ld B

= 7

3.Raw

dat

a ra

nked

and

in s

uita

ble

tabl

e fo

rmat

of

row

s an

d co

lum

ns

4.Acc

urat

e he

adin

gs e

.g.

N

umbe

r of

wor

ms

in

{qua

drat

/0.2

5m2 }

Fi

eld

A

Fiel

d B

13

15

10

12

9

10

9

9

8 8

5

7

4 6

4

6

3 4

3

0

ACCEP

T su

itabl

e ta

bles

tur

ned

90o .

IGN

ORE

omis

sion

of

rule

d lin

es w

ithin

bod

y of

tab

le

and

unra

nked

dat

a.

NO

T 0.

5m2 .

NO

T if

no r

efer

ence

to

quad

rat/

area

.

(4)


241

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

2(c

) A

axe

s co

rrec

t or

ient

atio

n an

d sc

ale

with

sui

tabl

e la

bels

Pda

ta p

lott

ed a

s ba

r ch

art

with

bars

plot

ted

corr

ectly

B r

ange

bar

incl

uded

A E

xpec

t to

see

med

ian

in y

-axi

s la

bel.

ACCEP

T ec

f fo

r un

its b

ut n

ot n

o un

its.

P ACCEP

T m

eans

if in

2(b

) m

eans

cal

cula

ted

or

med

ians

inco

rrec

tly c

alcu

late

d.

(3)

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

2(d

) 1.

The

(sm

alle

r) v

alue

of {U

/eq}

is h

ighe

r th

an

the

criti

cal v

alue

2.Ref

eren

ce t

o cr

itica

l val

ue o

f 23

3.Th

eref

ore

ther

e is

no

sig

nif

ican

t d

iffe

ren

cebe

twee

n th

e nu

mbe

r of

wor

ms

{com

ing

to t

he

surf

ace

in e

ach

quad

rat/

foun

d in

eac

h fie

ld/e

q}

4.Acc

ept

null

hypo

thes

is/e

q

5.Ref

eren

ce t

o {w

ide

vari

abili

ty o

f da

ta/m

edia

ns

are

very

clo

se t

oget

her/

eq}

ACCEP

T cl

earl

y m

arke

d va

lue

in t

able

.

Cre

dit

do

not

reje

ct

IGN

ORE

over

lapp

ing

erro

r ba

rs.

(4)


242

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

2(e

)1.

Idea

tha

t ot

her

fact

ors

may

not

hav

e be

en t

aken

in

to c

onsi

dera

tion

2.Sam

ple

size

sm

all/

sam

ple

only

tak

en a

t on

e tim

e pe

riod

/eq

3.Ref

eren

ce t

o {w

ide

vari

abili

ty o

f da

ta/e

q}

ACCEP

T na

med

fac

tor.

IGN

ORE

differ

ence

in n

umbe

r of

qua

drat

s sa

mpl

ed.

IGN

ORE

over

lapp

ing

erro

r/ra

nge

bars

.

(3)

Tota

l fo

r Q

ues

tio

n 2

= 1

6 M

arks

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

3(a

) 1.

Sui

tabl

e et

hica

l arg

umen

t, e

.g.

ther

e is

no

sign

ifica

nt e

thic

al is

sue

2.Th

ere

are

no s

igni

fican

t sa

fety

issu

es

3.Saf

ety

issu

e re

late

d to

min

eral

s, e

.g.

min

eral

al

lerg

ies

or ir

rita

nts

4.Saf

ety

issu

e re

late

d to

pla

nts,

e.g

. pl

ant

alle

rgie

s or

irri

tant

s

5.Saf

ety

rela

ted

to h

ydro

poni

cs,

e.g.

may

pro

vide

go

od g

row

ing

cond

ition

s fo

r ba

cter

ia/f

ungi

IGN

ORE

idea

tha

t re

mov

ing

plan

ts fro

m e

nviron

men

t is

an

ethi

cal c

once

rn.

IGN

ORE

{sol

utio

ns/c

hem

ical

s} m

ay b

e co

rros

ive.

(2

)


243

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

3(b

) 1.

See

if p

ropo

sed

met

hod

will

wor

k/eq

2.See

if t

he p

lant

cho

sen

will

gro

w in

hyd

ropo

nic

unit/

eq

3.Id

ea o

f se

lect

ing

rang

e of

Mg

conc

entr

atio

ns

4.Fi

nd s

uita

ble

met

hod

of m

easu

ring

{g

row

th/y

ield

/col

our

of le

aves

/nu

mbe

r of

le

aves

/eq}

5.Che

ck m

ost

suita

ble

cond

ition

s (f

or g

row

th o

f pl

ants

) /e

q

6.Sel

ect

suita

ble

times

cale

for

mea

suri

ng g

row

th/e

q

Igno

re p

ract

ice

prop

osed

met

hod

.

(3)


244

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

3 (

c)

1.Cle

ar s

tate

men

t of

dep

ende

nt v

aria

ble,

i.e.

exa

ctly

w

hat

is t

o be

mea

sure

d st

ated

, e.

g. m

ass

of p

lant

tis

sue,

mas

s of

fru

it, le

ngth

of

shoo

t,

{num

ber/

colo

ur}

of le

aves

/eq

2.Cle

ar d

escr

iptio

n of

met

hod

of m

easu

ring

cha

nge

in d

epen

dent

var

iabl

e

3.Cle

ar s

tate

men

t of

inde

pend

ent

vari

able

=

conc

entr

atio

n of

mag

nesi

um

4.Ran

ge o

f su

itabl

e co

ncen

trat

ions

sug

gest

ed (

at

leas

t 5)

5.Som

e cl

ear

cons

ider

atio

n of

tim

e pe

riod

ove

r w

hich

the

gro

wth

will

be

mea

sure

d/eq

6.an

d 7.

Ide

ntifi

catio

n of

up

to 2

oth

er v

aria

bles

tha

t co

uld

affe

ct g

row

th

8.an

d 9.

Des

crip

tion

of h

ow t

hose

2 id

entif

ied

variab

les

can

be c

ontr

olle

d

10.I

dea

of n

eed

for

repl

ica

at e

ach

conc

entr

atio

n

11.c

ontr

ol o

f so

urce

of

plan

t, e

.g.

use

of s

ame

spec

ies/

variet

y/so

urce

of

seed

s

12.U

se o

f gr

aph

to id

entify

oth

er v

alue

s of

co

ncen

trat

ion

t

o te

st t

o id

entif

y op

timum

co

ncen

trat

ion/

eq

Nee

d to

see

ter

m d

epen

dent

var

iabl

e.

Des

crip

tion

of c

alcu

latio

ns n

ot r

equi

red.

Nee

d to

see

ter

m in

depe

nden

t va

riab

le.

ACCEP

T a

stat

emen

t th

at 5

diff

eren

t co

ncen

trat

ions

w

ould

be

used

. IG

NO

RE

answ

ers

of f

ewer

tha

n 3

days

.

ACCEP

T vo

lum

e of

sol

utio

ns f

or o

ne o

f th

ese

mar

ks.

Mus

t de

scribe

how

var

iabl

es a

re c

ontr

olle

d. I

gnor

e re

spon

ses

such

as

use

a g

reen

hous

e/

put

them

so

mew

here

with

the

sam

e lig

ht in

tens

ity.

Idea

of co

ntro

lling

for

gen

etic

var

iabi

lity.

(8)

+

(2 S

PG

-

see

bel

ow

)


245

Sp

ellin

g,

Pu

nct

uat

ion

an

d G

ram

mar

(S

PG

) -

Aw

ard

up

to

2 m

arks

Sta

rt w

ith

2 m

arks

an

d if

cri

teri

a n

ot m

et m

ove

to 1

an

d t

hen

0

Leve

lM

ark

Des

crip

tor

Leve

l 3

2

The

acco

unt

is w

ell o

rgan

ised

with

no

undu

e re

petit

ion

and

a co

rrec

t se

quen

ce.

Ther

e is

goo

d us

e of

sc

ient

ific

voca

bula

ry in

the

con

text

of

the

inve

stig

atio

n de

scri

bed.

The

acc

ount

is w

ritt

en in

con

tinuo

us

pros

e w

hich

is g

ram

mat

ical

ly s

ound

with

no

maj

or s

pelli

ng e

rror

s.

Leve

l 2

1

Ther

e is

som

e di

sorg

anis

atio

n in

the

acc

ount

whi

ch is

not

alw

ays

in t

he c

orre

ct s

eque

nce.

Som

e re

leva

nt

scie

ntifi

c vo

cabu

lary

is u

sed.

The

acc

ount

is n

ot a

lway

s in

con

tinuo

us p

rose

and

the

re a

re g

ram

mat

ical

er

rors

and

som

e im

port

ant

spel

ling

mis

take

s.

Leve

l 1

0

The

acco

unt

is v

ery

diso

rgan

ised

and

is v

ery

diffic

ult

to fol

low

. Sci

entif

ic v

ocab

ular

y is

ver

y lim

ited

with

m

any

spel

ling

and

gram

mat

ical

err

ors.

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

3(d

) 1.

Cle

ar t

able

whi

ch m

atch

es m

etho

d de

scribe

d w

ith

head

ings

and

uni

ts

2.Cha

nge

in {

grow

th/e

q} c

alcu

late

d, e

.g.

by

mea

suring

{ch

ange

in le

ngth

/per

cent

age

chan

ge in

m

ass/

eq}

3.M

eans

cal

cula

ted

from

rep

eat

data

4.{S

catt

er/l

ine}

gra

ph for

mat

with

cor

rect

ly-l

abel

led

ax

es/e

q

5.U

se o

f gr

aph

to {

estim

ate

rang

e fo

r op

timum

/to

iden

tify

othe

r va

lues

of co

ncen

trat

ion

to t

est

to

iden

tify

optim

um c

once

ntra

tion/

eq}

Tabl

e w

ith c

olum

ns/r

ows

for

raw

dat

a. I

gnor

e un

its in

bo

dy o

f ta

ble.

(4)


246

Qu

esti

on

Nu

mb

er

An

swer

A

dd

itio

nal

Gu

idan

ce

Mar

k

3(e

)1.

Diff

icul

t to

con

trol

all

vari

able

s af

fect

ing

plan

t gr

owth

2.Ex

ampl

e of

unc

ontr

olle

d va

riab

le,

e.g.

see

ds d

o no

t ge

rmin

ate

at t

he s

ame

time,

gen

etic

di

ffer

ence

s be

twee

n th

e pl

ants

3.Ref

eren

ce t

o lim

iting

fac

tor(

s)

4.Ref

eren

ce t

o ne

ed for

mor

e th

an o

ne t

ype

of

min

eral

for

eff

ectiv

e gr

owth

of

plan

ts

5.Spe

cifie

d di

ffic

ulty

in m

easu

ring

dep

ende

nt

variab

le/e

q

Nee

ds t

o be

rel

ated

to

plan

t gr

owth

.

Sim

ply

stat

ing

that

a p

artic

ular

var

iabl

e w

as n

ot

cont

rolle

d ga

ins

only

.

ACCEP

T co

ntam

inat

ion

with

mic

roor

gani

sms

may

af

fect

pla

nt g

row

th.

IGN

ORE

refe

renc

e to

poo

r ch

oice

of

depe

nden

t va

riab

le.

(3)

Tota

l fo

r Q

ues

tio

n 3

= 2

2 M

arks

Tota

l for

Pap

er =

50

Mar

ks

specimen (ial) ms - unit 6 edexcel biology

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