29Biology guide 29

Core Topi

c 1:

Cel

l bio

logy

15

hou

rs

Esse

ntia

l ide

a: T

he e

volu

tion

of m

ultic

ellu

lar o

rgan

ism

s al

low

ed c

ell s

peci

aliz

atio

n an

d ce

ll re

plac

emen

t.

1.1

Intr

oduc

tion

to c

ells

Nat

ure

of s

cien

ce:

Look

ing

for t

rend

s an

d di

scre

panc

ies—

alth

ough

mos

t org

anis

ms

conf

orm

to c

ell t

heor

y, th

ere

are

exce

ptio

ns. (

3.1)

Ethi

cal i

mpl

icat

ions

of r

esea

rch—

rese

arch

invo

lvin

g st

em c

ells

is g

row

ing

in im

port

ance

and

rais

es e

thic

al is

sues

. (4.

5)

Und

erst

andi

ngs:

• A

ccor

ding

to th

e ce

ll th

eory

, liv

ing

orga

nism

s ar

e co

mpo

sed

of c

ells

.

• O

rgan

ism

s co

nsis

ting

of o

nly

one

cell

carr

y ou

t all

func

tions

of l

ife in

that

cel

l.

• Su

rfac

e ar

ea to

vol

ume

ratio

is im

port

ant i

n th

e lim

itatio

n of

cel

l siz

e.

• M

ultic

ellu

lar o

rgan

ism

s ha

ve p

rope

rtie

s th

at e

mer

ge fr

om th

e in

tera

ctio

n of

th

eir c

ellu

lar c

ompo

nent

s.

• Sp

ecia

lized

tiss

ues

can

deve

lop

by c

ell d

iffer

entia

tion

in m

ultic

ellu

lar

orga

nism

s.

• D

iffer

entia

tion

invo

lves

the

expr

essi

on o

f som

e ge

nes

and

not o

ther

s in

a

cell’

s ge

nom

e.

• Th

e ca

paci

ty o

f ste

m c

ells

to d

ivid

e an

d di

ffer

entia

te a

long

diff

eren

t pa

thw

ays

is n

eces

sary

in e

mbr

yoni

c de

velo

pmen

t and

als

o m

akes

ste

m c

ells

su

itabl

e fo

r the

rape

utic

use

s.

Inte

rnat

iona

l-m

inde

dnes

s:

• St

em c

ell r

esea

rch

has

depe

nded

on

the

wor

k of

team

s of

sci

entis

ts in

man

y co

untr

ies

who

sha

re re

sults

ther

eby

spee

ding

up

the

rate

of p

rogr

ess.

H

owev

er, n

atio

nal g

over

nmen

ts a

re in

fluen

ced

by lo

cal,

cultu

ral a

nd re

ligio

us

trad

ition

s th

at im

pact

on

the

wor

k of

sci

entis

ts a

nd th

e us

e of

ste

m c

ells

in

ther

apy.

Theo

ry o

f kno

wle

dge:

• Th

ere

is a

diff

eren

ce b

etw

een

the

livin

g an

d th

e no

n-liv

ing

envi

ronm

ent.

How

are

we

able

to k

now

the

diff

eren

ce?

Uti

lizat

ion:

• Th

e us

e of

ste

m c

ells

in th

e tr

eatm

ent o

f dis

ease

is m

ostly

at t

he e

xper

imen

tal

stag

e, w

ith th

e ex

cept

ion

of b

one

mar

row

ste

m c

ells

. Sci

entis

ts, h

owev

er,

antic

ipat

e th

e us

e of

ste

m c

ell t

hera

pies

as

a st

anda

rd m

etho

d of

trea

ting

a w

hole

rang

e of

dis

ease

s in

the

near

futu

re, i

nclu

ding

hea

rt d

isea

se a

nd

diab

etes

.

Topic 1: Cell biology

Biology guide30

1.1

Intr

oduc

tion

to c

ells

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: Q

uest

ioni

ng th

e ce

ll th

eory

usi

ng a

typi

cal e

xam

ples

, inc

ludi

ng

stria

ted

mus

cle,

gia

nt a

lgae

and

ase

ptat

e fu

ngal

hyp

hae.

• A

pplic

atio

n: In

vest

igat

ion

of fu

nctio

ns o

f life

in P

aram

eciu

m a

nd o

ne n

amed

ph

otos

ynth

etic

uni

cellu

lar o

rgan

ism

.

• A

pplic

atio

n: U

se o

f ste

m c

ells

to tr

eat S

targ

ardt

’s di

seas

e an

d on

e ot

her

nam

ed c

ondi

tion.

• A

pplic

atio

n: E

thic

s of

the

ther

apeu

tic u

se o

f ste

m c

ells

from

spe

cial

ly c

reat

ed

embr

yos,

from

the

umbi

lical

cor

d bl

ood

of a

new

-bor

n ba

by a

nd fr

om a

n ad

ult’s

ow

n tis

sues

.

• Sk

ill: U

se o

f a li

ght m

icro

scop

e to

inve

stig

ate

the

stru

ctur

e of

cel

ls a

nd

tissu

es, w

ith d

raw

ing

of c

ells

. Cal

cula

tion

of th

e m

agni

ficat

ion

of d

raw

ings

an

d th

e ac

tual

siz

e of

str

uctu

res

and

ultr

astr

uctu

res

show

n in

dra

win

gs o

r m

icro

grap

hs. (

Prac

tical

1)

Gui

danc

e:

• St

uden

ts a

re e

xpec

ted

to b

e ab

le to

nam

e an

d br

iefly

exp

lain

thes

e fu

nctio

ns

of li

fe: n

utrit

ion,

met

abol

ism

, gro

wth

, res

pons

e, e

xcre

tion,

hom

eost

asis

and

re

prod

uctio

n.

• Ch

lore

lla o

r Sce

nede

smus

are

sui

tabl

e ph

otos

ynth

etic

uni

cells

, but

Eug

lena

sh

ould

be

avoi

ded

as it

can

feed

het

erot

roph

ical

ly.

• Sc

ale

bars

are

use

ful a

s a

way

of i

ndic

atin

g ac

tual

siz

es in

dra

win

gs a

nd

mic

rogr

aphs

.

Aim

s:

• A

im 8

: The

re a

re e

thic

al is

sues

invo

lved

in s

tem

cel

l res

earc

h, w

heth

er

hum

ans

or o

ther

ani

mal

s ar

e us

ed. U

se o

f em

bryo

nic

stem

cel

ls in

volv

es

the

deat

h of

ear

ly-s

tage

em

bryo

s, b

ut if

ther

apeu

tic c

loni

ng is

suc

cess

fully

de

velo

ped

the

suff

erin

g of

pat

ient

s w

ith a

wid

e va

riety

of c

ondi

tions

cou

ld

be re

duce

d.

Topic 1: Cell biology

Biology guide 31

Esse

ntia

l ide

a: E

ukar

yote

s ha

ve a

muc

h m

ore

com

plex

cel

l str

uctu

re th

an p

roka

ryot

es.

1.2

Ult

rast

ruct

ure

of c

ells

Nat

ure

of s

cien

ce:

Dev

elop

men

ts in

sci

entif

ic re

sear

ch fo

llow

impr

ovem

ents

in a

ppar

atus

—th

e in

vent

ion

of e

lect

ron

mic

rosc

opes

led

to g

reat

er u

nder

stan

ding

of c

ell s

truc

ture

. (1.

8)

Und

erst

andi

ngs:

• Pr

okar

yote

s ha

ve a

sim

ple

cell

stru

ctur

e w

ithou

t com

part

men

taliz

atio

n.

• Eu

kary

otes

hav

e a

com

part

men

taliz

ed c

ell s

truc

ture

.

• El

ectr

on m

icro

scop

es h

ave

a m

uch

high

er re

solu

tion

than

ligh

t mic

rosc

opes

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: S

truc

ture

and

func

tion

of o

rgan

elle

s w

ithin

exo

crin

e gl

and

cells

of

the

panc

reas

and

with

in p

alis

ade

mes

ophy

ll ce

lls o

f the

leaf

.

• A

pplic

atio

n: P

roka

ryot

es d

ivid

e by

bin

ary

fissi

on.

• Sk

ill: D

raw

ing

of th

e ul

tras

truc

ture

of p

roka

ryot

ic c

ells

bas

ed o

n el

ectr

on

mic

rogr

aphs

.

• Sk

ill: D

raw

ing

of th

e ul

tras

truc

ture

of e

ukar

yotic

cel

ls b

ased

on

elec

tron

m

icro

grap

hs.

• Sk

ill: I

nter

pret

atio

n of

ele

ctro

n m

icro

grap

hs to

iden

tify

orga

nelle

s an

d de

duce

the

func

tion

of s

peci

aliz

ed c

ells

.

Gui

danc

e:

• D

raw

ings

of p

roka

ryot

ic c

ells

sho

uld

show

the

cell

wal

l, pi

li an

d fla

gella

, and

pl

asm

a m

embr

ane

encl

osin

g cy

topl

asm

that

con

tain

s 70

S rib

osom

es a

nd a

nu

cleo

id w

ith n

aked

DN

A.

• D

raw

ings

of e

ukar

yotic

cel

ls s

houl

d sh

ow a

pla

sma

mem

bran

e en

clos

ing

cyto

plas

m th

at c

onta

ins

80S

ribos

omes

and

a n

ucle

us, m

itoch

ondr

ia a

nd

othe

r mem

bran

e-bo

und

orga

nelle

s ar

e pr

esen

t in

the

cyto

plas

m. S

ome

euka

ryot

ic c

ells

hav

e a

cell

wal

l.

Inte

rnat

iona

l-m

inde

dnes

s:

• M

icro

scop

es w

ere

inve

nted

sim

ulta

neou

sly

in d

iffer

ent p

arts

of t

he w

orld

at

a tim

e w

hen

info

rmat

ion

trav

elle

d sl

owly

. Mod

ern-

day

com

mun

icat

ions

hav

e al

low

ed fo

r im

prov

emen

ts in

the

abili

ty to

col

labo

rate

, enr

ichi

ng s

cien

tific

en

deav

our.

Theo

ry o

f kno

wle

dge:

• Th

e w

orld

that

we

inha

bit i

s lim

ited

by th

e w

orld

that

we

see.

Is th

ere

any

dist

inct

ion

to b

e dr

awn

betw

een

know

ledg

e cl

aim

s de

pend

ent u

pon

obse

rvat

ions

mad

e by

sen

se p

erce

ptio

n an

d kn

owle

dge

clai

ms

depe

nden

t up

on o

bser

vatio

ns a

ssis

ted

by te

chno

logy

?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Ph

ysic

s To

pic

4.4

Wav

e be

havi

our

Topi

c C

.1 In

trod

uctio

n to

imag

ing

Topi

c C

.3 F

ibre

optic

s

Aim

s:

• A

im 8

: Dev

elop

men

ts in

sci

ence

, suc

h as

ele

ctro

n m

icro

scop

y, c

an h

ave

econ

omic

ben

efits

as

they

giv

e co

mm

erci

al c

ompa

nies

opp

ortu

nitie

s to

m

ake

prof

its, b

ut th

is c

an a

ffec

t coo

pera

tion

betw

een

scie

ntis

ts.

Topic 1: Cell biology

Biology guide32

Esse

ntia

l ide

a: T

he s

truc

ture

of b

iolo

gica

l mem

bran

es m

akes

them

flui

d an

d dy

nam

ic.

1.3

Mem

bran

e st

ruct

ure

Nat

ure

of s

cien

ce:

Usi

ng m

odel

s as

repr

esen

tatio

ns o

f the

real

wor

ld—

ther

e ar

e al

tern

ativ

e m

odel

s of

mem

bran

e st

ruct

ure.

(1.11

)

Fals

ifica

tion

of th

eorie

s w

ith o

ne th

eory

bei

ng s

uper

sede

d by

ano

ther

—ev

iden

ce fa

lsifi

ed th

e D

avso

n-D

anie

lli m

odel

. (1.

9)

Und

erst

andi

ngs:

• Ph

osph

olip

ids

form

bila

yers

in w

ater

due

to th

e am

phip

athi

c pr

oper

ties

of

phos

phol

ipid

mol

ecul

es.

• M

embr

ane

prot

eins

are

div

erse

in te

rms

of s

truc

ture

, pos

ition

in th

e m

embr

ane

and

func

tion.

• Ch

oles

tero

l is

a co

mpo

nent

of a

nim

al c

ell m

embr

anes

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

hole

ster

ol in

mam

mal

ian

mem

bran

es re

duce

s m

embr

ane

fluid

ity a

nd p

erm

eabi

lity

to s

ome

solu

tes.

• Sk

ill: D

raw

ing

of th

e flu

id m

osai

c m

odel

.

• Sk

ill: A

naly

sis

of e

vide

nce

from

ele

ctro

n m

icro

scop

y th

at le

d to

the

prop

osal

of

the

Dav

son-

Dan

ielli

mod

el.

• Sk

ill: A

naly

sis

of th

e fa

lsifi

catio

n of

the

Dav

son-

Dan

ielli

mod

el th

at le

d to

the

Sing

er-N

icol

son

mod

el.

Gui

danc

e:

• A

mph

ipat

hic

phos

phol

ipid

s ha

ve h

ydro

phili

c an

d hy

drop

hobi

c pr

oper

ties.

• D

raw

ings

of t

he fl

uid

mos

aic

mod

el o

f mem

bran

e st

ruct

ure

can

be tw

o di

men

sion

al ra

ther

than

thre

e di

men

sion

al. I

ndiv

idua

l pho

spho

lipid

m

olec

ules

sho

uld

be s

how

n us

ing

the

sym

bol o

f a c

ircle

with

two

para

llel

lines

att

ache

d. A

rang

e of

mem

bran

e pr

otei

ns s

houl

d be

sho

wn

incl

udin

g gl

ycop

rote

ins.

Theo

ry o

f kno

wle

dge:

• Th

e ex

plan

atio

n of

the

stru

ctur

e of

the

plas

ma

mem

bran

e ha

s ch

ange

d ov

er

the

year

s as

new

evi

denc

e an

d w

ays

of a

naly

sis

have

com

e to

ligh

t. U

nder

w

hat c

ircum

stan

ces

is it

impo

rtan

t to

lear

n ab

out t

heor

ies

that

wer

e la

ter

disc

redi

ted?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

2.3

Carb

ohyd

rate

s an

d lip

ids

Topi

c 2.

6 St

ruct

ure

of D

NA

and

RN

A

Topic 1: Cell biology

Biology guide 33

Esse

ntia

l ide

a: M

embr

anes

con

trol

the

com

posi

tion

of c

ells

by

activ

e an

d pa

ssiv

e tr

ansp

ort.

1.4

Mem

bran

e tr

ansp

ort

Nat

ure

of s

cien

ce:

Expe

rimen

tal d

esig

n—ac

cura

te q

uant

itativ

e m

easu

rem

ent i

n os

mos

is e

xper

imen

ts a

re e

ssen

tial.

(3.1)

Und

erst

andi

ngs:

• Pa

rtic

les

mov

e ac

ross

mem

bran

es b

y si

mpl

e di

ffus

ion,

faci

litat

ed d

iffus

ion,

os

mos

is a

nd a

ctiv

e tr

ansp

ort.

• Th

e flu

idity

of m

embr

anes

allo

ws

mat

eria

ls to

be

take

n in

to c

ells

by

endo

cyto

sis

or re

leas

ed b

y ex

ocyt

osis

. Ves

icle

s m

ove

mat

eria

ls w

ithin

cel

ls.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: S

truc

ture

and

func

tion

of s

odiu

m–p

otas

sium

pum

ps fo

r act

ive

tran

spor

t and

pot

assi

um c

hann

els

for f

acili

tate

d di

ffus

ion

in a

xons

.

• A

pplic

atio

n: T

issu

es o

r org

ans

to b

e us

ed in

med

ical

pro

cedu

res

mus

t be

bath

ed in

a s

olut

ion

with

the

sam

e os

mol

arity

as

the

cyto

plas

m to

pre

vent

os

mos

is.

• Sk

ill: E

stim

atio

n of

osm

olar

ity in

tiss

ues

by b

athi

ng s

ampl

es in

hyp

oton

ic a

nd

hype

rton

ic s

olut

ions

. (Pr

actic

al 2

)

Gui

danc

e:

• O

smos

is e

xper

imen

ts a

re a

use

ful o

ppor

tuni

ty to

str

ess

the

need

for a

ccur

ate

mas

s an

d vo

lum

e m

easu

rem

ents

in s

cien

tific

exp

erim

ents

.

Uti

lizat

ion:

• Ki

dney

dia

lysi

s ar

tific

ially

mim

ics

the

func

tion

of th

e hu

man

kid

ney

by u

sing

ap

prop

riate

mem

bran

es a

nd d

iffus

ion

grad

ient

s.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

6.5

Neu

rons

and

syn

apse

s

Aim

s:

• A

im 8

: Org

an d

onat

ion

rais

es s

ome

inte

rest

ing

ethi

cal i

ssue

s, in

clud

ing

the

altr

uist

ic n

atur

e of

org

an d

onat

ion

and

conc

erns

abo

ut s

ale

of h

uman

org

ans.

• A

im 6

: Dia

lysi

s tu

bing

exp

erim

ents

can

act

as

a m

odel

of m

embr

ane

actio

n.

Expe

rimen

ts w

ith p

otat

o, b

eetr

oot o

r sin

gle-

celle

d al

gae

can

be u

sed

to

inve

stig

ate

real

mem

bran

es.

Topic 1: Cell biology

Biology guide34

Esse

ntia

l ide

a: T

here

is a

n un

brok

en c

hain

of l

ife fr

om th

e fir

st c

ells

on

Eart

h to

all

cells

in o

rgan

ism

s al

ive

toda

y.

1.5

The

orig

in o

f cel

ls

Nat

ure

of s

cien

ce:

Test

ing

the

gene

ral p

rinci

ples

that

und

erlie

the

natu

ral w

orld

—th

e pr

inci

ple

that

cel

ls o

nly

com

e fr

om p

re-e

xist

ing

cells

nee

ds to

be

verif

ied.

(1.9

)

Und

erst

andi

ngs:

• Ce

lls c

an o

nly

be fo

rmed

by

divi

sion

of p

re-e

xist

ing

cells

.

• Th

e fir

st c

ells

mus

t hav

e ar

isen

from

non

-livi

ng m

ater

ial.

• Th

e or

igin

of e

ukar

yotic

cel

ls c

an b

e ex

plai

ned

by th

e en

dosy

mbi

otic

theo

ry.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: E

vide

nce

from

Pas

teur

’s ex

perim

ents

that

spo

ntan

eous

ge

nera

tion

of c

ells

and

org

anis

ms

does

not

now

occ

ur o

n Ea

rth.

Gui

danc

e:

• Ev

iden

ce fo

r the

end

osym

biot

ic th

eory

is e

xpec

ted.

The

orig

in o

f euk

aryo

te

cilia

and

flag

ella

doe

s no

t nee

d to

be

incl

uded

.

• St

uden

ts s

houl

d be

aw

are

that

the

64 c

odon

s in

the

gene

tic c

ode

have

th

e sa

me

mea

ning

s in

nea

rly a

ll or

gani

sms,

but

that

ther

e ar

e so

me

min

or

varia

tions

that

are

like

ly to

hav

e ac

crue

d si

nce

the

com

mon

orig

in o

f life

on

Eart

h.

Theo

ry o

f kno

wle

dge:

• Bi

olog

y is

the

stud

y of

life

, yet

life

is a

n em

erge

nt p

rope

rty.

Und

er w

hat

circ

umst

ance

s is

a s

yste

ms

appr

oach

pro

duct

ive

in b

iolo

gy a

nd u

nder

w

hat c

ircum

stan

ces

is a

redu

ctio

nist

app

roac

h m

ore

appr

opria

te?

How

do

scie

ntis

ts d

ecid

e be

twee

n co

mpe

ting

appr

oach

es?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

5.1

Evid

ence

for e

volu

tion

Aim

s:

• A

im 6

: Pas

teur

’s ex

perim

ent c

an b

e re

peat

ed u

sing

mod

ern

appa

ratu

s.

Topic 1: Cell biology

Biology guide 35

Esse

ntia

l ide

a: C

ell d

ivis

ion

is e

ssen

tial b

ut m

ust b

e co

ntro

lled.

1.6

Cell

divi

sion

Nat

ure

of s

cien

ce:

Sere

ndip

ity a

nd s

cien

tific

dis

cove

ries—

the

disc

over

y of

cyc

lins

was

acc

iden

tal.

(1.4

)

Und

erst

andi

ngs:

• M

itosi

s is d

ivis

ion

of th

e nu

cleu

s int

o tw

o ge

netic

ally

iden

tical

dau

ghte

r nuc

lei.

• Ch

rom

osom

es c

onde

nse

by s

uper

coili

ng d

urin

g m

itosi

s.

• Cy

toki

nesi

s oc

curs

aft

er m

itosi

s an

d is

diff

eren

t in

plan

t and

ani

mal

cel

ls.

• In

terp

hase

is a

ver

y ac

tive

phas

e of

the

cell

cycl

e w

ith m

any

proc

esse

s oc

curr

ing

in th

e nu

cleu

s an

d cy

topl

asm

.

• Cy

clin

s ar

e in

volv

ed in

the

cont

rol o

f the

cel

l cyc

le.

• M

utag

ens,

onc

ogen

es a

nd m

etas

tasi

s ar

e in

volv

ed in

the

deve

lopm

ent o

f pr

imar

y an

d se

cond

ary

tum

ours

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: T

he c

orre

latio

n be

twee

n sm

okin

g an

d in

cide

nce

of c

ance

rs.

• Sk

ill: I

dent

ifica

tion

of p

hase

s of

mito

sis

in c

ells

vie

wed

with

a m

icro

scop

e or

in

a m

icro

grap

h.

• Sk

ill: D

eter

min

atio

n of

a m

itotic

inde

x fr

om a

mic

rogr

aph.

Gui

danc

e:

• Th

e se

quen

ce o

f eve

nts

in th

e fo

ur p

hase

s of

mito

sis

shou

ld b

e kn

own.

• Pr

epar

atio

n of

tem

pora

ry m

ount

s of

root

squ

ashe

s is

reco

mm

ende

d bu

t ph

ases

in m

itosi

s ca

n al

so b

e vi

ewed

usi

ng p

erm

anen

t slid

es.

• To

avo

id c

onfu

sion

in te

rmin

olog

y, te

ache

rs a

re e

ncou

rage

d to

refe

r to

the

two

part

s of

a c

hrom

osom

e as

sis

ter c

hrom

atid

s, w

hile

they

are

att

ache

d to

ea

ch o

ther

by

a ce

ntro

mer

e in

the

early

sta

ges

of m

itosi

s. F

rom

ana

phas

e on

war

ds, w

hen

sist

er c

hrom

atid

s ha

ve s

epar

ated

to fo

rm in

divi

dual

st

ruct

ures

, the

y sh

ould

be

refe

rred

to a

s ch

rom

osom

es.

Inte

rnat

iona

l-m

inde

dnes

s:

• Bi

olog

ists

in la

bora

torie

s th

roug

hout

the

wor

ld a

re re

sear

chin

g in

to th

e ca

uses

and

trea

tmen

t of c

ance

r.

Theo

ry o

f kno

wle

dge:

• A

num

ber o

f sci

entif

ic d

isco

verie

s ar

e cl

aim

ed to

be

inci

dent

al o

r se

rend

ipito

us. T

o w

hat e

xten

t mig

ht s

ome

of th

ese

scie

ntifi

c di

scov

erie

s be

th

e re

sult

of in

tuiti

on ra

ther

than

luck

?

Uti

lizat

ion:

• Th

e m

itotic

inde

x is

an

impo

rtan

t pro

gnos

tic to

ol fo

r pre

dict

ing

the

resp

onse

of

can

cer c

ells

to c

hem

othe

rapy

.

Aim

s:

• A

im 8

: The

toba

cco

indu

stry

cou

ld b

e di

scus

sed.

Sup

pres

sion

of t

he re

sults

of

rese

arch

by

toba

cco

com

pani

es in

to th

e he

alth

eff

ects

of s

mok

ing

toba

cco

was

une

thic

al. S

mok

ing

caus

es c

onsi

dera

ble

soci

al h

arm

, but

, with

the

exce

ptio

n of

law

s on

pro

duct

ion

and

supp

ly in

Bhu

tan,

has

nev

er b

een

mad

e ill

egal

.

Biology guide36

Core Topi

c 2:

Mol

ecul

ar b

iolo

gy

21 h

ours

Esse

ntia

l ide

a: L

ivin

g or

gani

sms

cont

rol t

heir

com

posi

tion

by a

com

plex

web

of c

hem

ical

reac

tions

.

2.1

Mol

ecul

es to

met

abol

ism

Nat

ure

of s

cien

ce:

Fals

ifica

tion

of th

eorie

s—th

e ar

tific

ial s

ynth

esis

of u

rea

help

ed to

fals

ify v

italis

m. (

1.9)

Und

erst

andi

ngs:

• M

olec

ular

bio

logy

exp

lain

s liv

ing

proc

esse

s in

term

s of

the

chem

ical

su

bsta

nces

invo

lved

.

• Ca

rbon

ato

ms

can

form

four

cov

alen

t bon

ds a

llow

ing

a di

vers

ity o

f sta

ble

com

poun

ds to

exi

st.

• Li

fe is

bas

ed o

n ca

rbon

com

poun

ds in

clud

ing

carb

ohyd

rate

s, li

pids

, pro

tein

s an

d nu

clei

c ac

ids.

• M

etab

olis

m is

the

web

of a

ll th

e en

zym

e-ca

taly

sed

reac

tions

in a

cel

l or

orga

nism

.

• A

nabo

lism

is th

e sy

nthe

sis

of c

ompl

ex m

olec

ules

from

sim

pler

mol

ecul

es

incl

udin

g th

e fo

rmat

ion

of m

acro

mol

ecul

es fr

om m

onom

ers

by c

onde

nsat

ion

reac

tions

.

• Ca

tabo

lism

is th

e br

eakd

own

of c

ompl

ex m

olec

ules

into

sim

pler

mol

ecul

es

incl

udin

g th

e hy

drol

ysis

of m

acro

mol

ecul

es in

to m

onom

ers.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s: Ch

emis

try

To

pic

4 Ch

emic

al b

ondi

ng a

nd s

truc

ture

O

ptio

n B

Bioc

hem

istr

y

Aim

s:

• A

im 7

: IC

T ca

n be

use

d fo

r mol

ecul

ar v

isua

lizat

ion

of c

arbo

hydr

ates

, lip

ids

and

prot

eins

in th

is s

ub-t

opic

and

in 2

.3 a

nd 2

.4.

• A

im 6

: Foo

d te

sts

such

as

the

use

of io

dine

to id

entif

y st

arch

or B

ened

ict’s

re

agen

t to

iden

tify

redu

cing

sug

ars

coul

d be

car

ried

out.

Topic 2: Molecular biology

Biology guide 37

2.1

Mol

ecul

es to

met

abol

ism

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

rea

as a

n ex

ampl

e of

a c

ompo

und

that

is p

rodu

ced

by li

ving

or

gani

sms

but c

an a

lso

be a

rtifi

cial

ly s

ynth

esiz

ed.

• Sk

ill: D

raw

ing

mol

ecul

ar d

iagr

ams

of g

luco

se, r

ibos

e, a

sat

urat

ed fa

tty

acid

an

d a

gene

raliz

ed a

min

o ac

id.

• Sk

ill: I

dent

ifica

tion

of b

ioch

emic

als

such

as

suga

rs, l

ipid

s or

am

ino

acid

s fr

om

mol

ecul

ar d

iagr

ams.

Gui

danc

e:

• O

nly

the

ring

form

s of

D-r

ibos

e, a

lpha

–D-g

luco

se a

nd b

eta-

D-g

luco

se a

re

expe

cted

in d

raw

ings

.

• Su

gars

incl

ude

mon

osac

char

ides

and

dis

acch

arid

es.

• O

nly

one

satu

rate

d fa

t is

expe

cted

and

its

spec

ific

nam

e is

not

nec

essa

ry.

• Th

e va

riabl

e ra

dica

l of a

min

o ac

ids

can

be s

how

n as

R. T

he s

truc

ture

of

indi

vidu

al R

-gro

ups

does

not

nee

d to

be

mem

oriz

ed.

• St

uden

ts s

houl

d be

abl

e to

reco

gniz

e fr

om m

olec

ular

dia

gram

s th

at

trig

lyce

rides

, pho

spho

lipid

s an

d st

eroi

ds a

re li

pids

. Dra

win

gs o

f ste

roid

s ar

e no

t exp

ecte

d.

• Pr

otei

ns o

r par

ts o

f pol

ypep

tides

sho

uld

be re

cogn

ized

from

mol

ecul

ar

diag

ram

s sh

owin

g am

ino

acid

s lin

ked

by p

eptid

e bo

nds.

Topic 2: Molecular biology

Biology guide38

Esse

ntia

l ide

a: W

ater

is th

e m

ediu

m o

f life

.

2.2

Wat

er

Nat

ure

of s

cien

ce:

Use

theo

ries

to e

xpla

in n

atur

al p

heno

men

a—th

e th

eory

that

hyd

roge

n bo

nds

form

bet

wee

n w

ater

mol

ecul

es e

xpla

ins

the

prop

ertie

s of

wat

er. (

2.2)

Und

erst

andi

ngs:

• W

ater

mol

ecul

es a

re p

olar

and

hyd

roge

n bo

nds

form

bet

wee

n th

em.

• H

ydro

gen

bond

ing

and

dipo

larit

y ex

plai

n th

e co

hesi

ve, a

dhes

ive,

ther

mal

an

d so

lven

t pro

pert

ies

of w

ater

.

• Su

bsta

nces

can

be

hydr

ophi

lic o

r hyd

roph

obic

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

ompa

rison

of t

he th

erm

al p

rope

rtie

s of

wat

er w

ith th

ose

of

met

hane

.

• A

pplic

atio

n: U

se o

f wat

er a

s a

cool

ant i

n sw

eat.

• A

pplic

atio

n: M

odes

of t

rans

port

of g

luco

se, a

min

o ac

ids,

cho

lest

erol

, fat

s,

oxyg

en a

nd s

odiu

m c

hlor

ide

in b

lood

in re

latio

n to

thei

r sol

ubili

ty in

wat

er.

Gui

danc

e:

• St

uden

ts s

houl

d kn

ow a

t lea

st o

ne e

xam

ple

of a

ben

efit

to li

ving

org

anis

ms

of e

ach

prop

erty

of w

ater

.

• Tr

ansp

aren

cy o

f wat

er a

nd m

axim

um d

ensi

ty a

t 4°C

do

not n

eed

to b

e in

clud

ed.

• Co

mpa

rison

of t

he th

erm

al p

rope

rtie

s of

wat

er a

nd m

etha

ne a

ssis

ts in

the

unde

rsta

ndin

g of

the

sign

ifica

nce

of h

ydro

gen

bond

ing

in w

ater

.

Inte

rnat

iona

l-m

inde

dnes

s:

• Th

ere

are

chal

leng

es fo

r the

incr

easi

ng h

uman

pop

ulat

ion

in s

harin

g w

ater

re

sour

ces

equi

tabl

y fo

r drin

king

and

irrig

atio

n, e

lect

ricity

gen

erat

ion

and

a ra

nge

of in

dust

rial a

nd d

omes

tic p

roce

sses

.

Theo

ry o

f kno

wle

dge:

• Cl

aim

s ab

out t

he “m

emor

y of

wat

er” h

ave

been

cat

egor

ized

as

pseu

dosc

ient

ific.

Wha

t are

the

crite

ria th

at c

an b

e us

ed to

dis

tingu

ish

scie

ntifi

c cl

aim

s fr

om p

seud

osci

entif

ic c

laim

s?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

4.3

Carb

on c

yclin

gTo

pic

4.4

Clim

ate

chan

gePh

ysic

s To

pic

3.1

Ther

mal

con

cept

s

Aim

s:

• A

im 6

: Pro

bes

can

be u

sed

to d

eter

min

e th

e ef

fect

of d

iffer

ent f

acto

rs li

kely

to

influ

ence

coo

ling

with

wat

er.

Topic 2: Molecular biology

Biology guide 39

Esse

ntia

l ide

a: C

ompo

unds

of c

arbo

n, h

ydro

gen

and

oxyg

en a

re u

sed

to s

uppl

y an

d st

ore

ener

gy.

2.3

Carb

ohyd

rate

s an

d lip

ids

Nat

ure

of s

cien

ce:

Eval

uatin

g cl

aim

s—he

alth

cla

ims

mad

e ab

out l

ipid

s in

die

ts n

eed

to b

e as

sess

ed. (

5.2)

Und

erst

andi

ngs:

• M

onos

acch

arid

e m

onom

ers

are

linke

d to

geth

er b

y co

nden

satio

n re

actio

ns to

fo

rm d

isac

char

ides

and

pol

ysac

char

ide

poly

mer

s.

• Fa

tty

acid

s ca

n be

sat

urat

ed, m

onou

nsat

urat

ed o

r pol

yuns

atur

ated

.

• U

nsat

urat

ed fa

tty

acid

s ca

n be

cis

or t

rans

isom

ers.

• Tr

igly

cerid

es a

re fo

rmed

by

cond

ensa

tion

from

thre

e fa

tty

acid

s and

one

gly

cero

l.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: S

truc

ture

and

func

tion

of c

ellu

lose

and

sta

rch

in p

lant

s an

d gl

ycog

en in

hum

ans.

• A

pplic

atio

n: S

cien

tific

evi

denc

e fo

r hea

lth ri

sks

of tr

ans

fats

and

sat

urat

ed

fatt

y ac

ids.

• A

pplic

atio

n: L

ipid

s ar

e m

ore

suita

ble

for l

ong-

term

ene

rgy

stor

age

in h

uman

s th

an c

arbo

hydr

ates

.

• A

pplic

atio

n: E

valu

atio

n of

evi

denc

e an

d th

e m

etho

ds u

sed

to o

btai

n th

e ev

iden

ce fo

r hea

lth c

laim

s m

ade

abou

t lip

ids.

• Sk

ill: U

se o

f mol

ecul

ar v

isua

lizat

ion

soft

war

e to

com

pare

cel

lulo

se, s

tarc

h an

d gl

ycog

en.

• Sk

ill: D

eter

min

atio

n of

bod

y m

ass

inde

x by

cal

cula

tion

or u

se o

f a n

omog

ram

.

Gui

danc

e:

• Th

e st

ruct

ure

of s

tarc

h sh

ould

incl

ude

amyl

ose

and

amyl

opec

tin.

• N

amed

exa

mpl

es o

f fat

ty a

cids

are

not

requ

ired.

• Su

cros

e, la

ctos

e an

d m

alto

se s

houl

d be

incl

uded

as

exam

ples

of

disa

ccha

rides

pro

duce

d by

com

bini

ng m

onos

acch

arid

es.

Inte

rnat

iona

l-m

inde

dnes

s:

• Va

riatio

n in

the

prev

alen

ce o

f diff

eren

t hea

lth p

robl

ems

arou

nd th

e w

orld

co

uld

be d

iscu

ssed

incl

udin

g ob

esity

, die

tary

ene

rgy

defic

ienc

y, k

was

hior

kor,

anor

exia

ner

vosa

and

cor

onar

y he

art d

isea

se.

Theo

ry o

f kno

wle

dge:

• Th

ere

are

conf

lictin

g vi

ews

as to

the

harm

s an

d be

nefit

s of

fats

in d

iets

. How

do

we

deci

de b

etw

een

com

petin

g vi

ews?

Uti

lizat

ion:

• Po

tato

es h

ave

been

gen

etic

ally

mod

ified

to re

duce

the

leve

l of a

myl

ose

to

prod

uce

a m

ore

effe

ctiv

e ad

hesi

ve.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yO

ptio

n B:

Bio

tech

nolo

gy a

nd b

ioin

form

atic

s

Aim

s:

• A

im 8

: The

re a

re s

ocia

l im

plic

atio

ns o

f obe

sity

.

Topic 2: Molecular biology

Biology guide40

Esse

ntia

l ide

a: P

rote

ins

have

a v

ery

wid

e ra

nge

of fu

nctio

ns in

livi

ng o

rgan

ism

s.

2.4

Prot

eins

Nat

ure

of s

cien

ce:

Look

ing

for p

atte

rns,

tren

ds a

nd d

iscr

epan

cies

—m

ost b

ut n

ot a

ll or

gani

sms

asse

mbl

e pr

otei

ns fr

om th

e sa

me

amin

o ac

ids.

(3.1)

Und

erst

andi

ngs:

• A

min

o ac

ids

are

linke

d to

geth

er b

y co

nden

satio

n to

form

pol

ypep

tides

.

• Th

ere

are

20 d

iffer

ent a

min

o ac

ids

in p

olyp

eptid

es s

ynth

esiz

ed o

n rib

osom

es.

• A

min

o ac

ids

can

be li

nked

toge

ther

in a

ny s

eque

nce

givi

ng a

hug

e ra

nge

of

poss

ible

pol

ypep

tides

.

• Th

e am

ino

acid

seq

uenc

e of

pol

ypep

tides

is c

oded

for b

y ge

nes.

• A

pro

tein

may

con

sist

of a

sin

gle

poly

pept

ide

or m

ore

than

one

pol

ypep

tide

linke

d to

geth

er.

• Th

e am

ino

acid

seq

uenc

e de

term

ines

the

thre

e-di

men

sion

al c

onfo

rmat

ion

of

a pr

otei

n.

• Li

ving

org

anis

ms

synt

hesi

ze m

any

diff

eren

t pro

tein

s w

ith a

wid

e ra

nge

of

func

tions

.

• Ev

ery

indi

vidu

al h

as a

uni

que

prot

eom

e.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: R

ubis

co, i

nsul

in, i

mm

unog

lobu

lins,

rhod

opsi

n, c

olla

gen

and

spid

er s

ilk a

s ex

ampl

es o

f the

rang

e of

pro

tein

func

tions

.

• A

pplic

atio

n: D

enat

urat

ion

of p

rote

ins

by h

eat o

r by

devi

atio

n of

pH

from

the

optim

um.

• Sk

ill: D

raw

ing

mol

ecul

ar d

iagr

ams

to s

how

the

form

atio

n of

a p

eptid

e bo

nd.

Uti

lizat

ion:

• Pr

oteo

mic

s an

d th

e pr

oduc

tion

of p

rote

ins

by c

ells

cul

ture

d in

ferm

ente

rs

offe

r man

y op

port

uniti

es fo

r the

food

, pha

rmac

eutic

al a

nd o

ther

indu

strie

s.

Aim

s:

• A

im 7

: IC

T ca

n be

use

d fo

r mol

ecul

ar v

isua

lizat

ion

of th

e st

ruct

ure

of

prot

eins

.

• A

im 8

: Obt

aini

ng s

ampl

es o

f hum

an b

lood

for i

mm

unol

ogic

al,

phar

mac

eutic

al a

nd a

nthr

opol

ogic

al s

tudi

es is

an

inte

rnat

iona

l end

eavo

ur

with

man

y et

hica

l iss

ues.

Topic 2: Molecular biology

Biology guide 41

2.4

Prot

eins

Gui

danc

e:

• Th

e de

taile

d st

ruct

ure

of th

e si

x pr

otei

ns s

elec

ted

to il

lust

rate

the

func

tions

of

pro

tein

s is

not

nee

ded.

• Eg

g w

hite

or a

lbum

in s

olut

ions

can

be

used

in d

enat

urat

ion

expe

rimen

ts.

• St

uden

ts s

houl

d kn

ow th

at m

ost o

rgan

ism

s us

e th

e sa

me

20 a

min

o ac

ids

in th

e sa

me

gene

tic c

ode

alth

ough

ther

e ar

e so

me

exce

ptio

ns. S

peci

fic

exam

ples

cou

ld b

e us

ed fo

r illu

stra

tion.

Topic 2: Molecular biology

Biology guide42

Esse

ntia

l ide

a: E

nzym

es c

ontr

ol th

e m

etab

olis

m o

f the

cel

l.

2.5

Enzy

mes

Nat

ure

of s

cien

ce:

Expe

rimen

tal d

esig

n—ac

cura

te, q

uant

itativ

e m

easu

rem

ents

in e

nzym

e ex

perim

ents

requ

ire re

plic

ates

to e

nsur

e re

liabi

lity.

(3.2

)

Und

erst

andi

ngs:

• En

zym

es h

ave

an a

ctiv

e si

te to

whi

ch s

peci

fic s

ubst

rate

s bi

nd.

• En

zym

e ca

taly

sis

invo

lves

mol

ecul

ar m

otio

n an

d th

e co

llisi

on o

f sub

stra

tes

with

the

activ

e si

te.

• Te

mpe

ratu

re, p

H a

nd s

ubst

rate

con

cent

ratio

n af

fect

the

rate

of a

ctiv

ity o

f en

zym

es.

• En

zym

es c

an b

e de

natu

red.

• Im

mob

ilize

d en

zym

es a

re w

idel

y us

ed in

indu

stry

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: M

etho

ds o

f pro

duct

ion

of la

ctos

e-fr

ee m

ilk a

nd it

s ad

vant

ages

.

• Sk

ill: D

esig

n of

exp

erim

ents

to te

st th

e ef

fect

of t

empe

ratu

re, p

H a

nd

subs

trat

e co

ncen

trat

ion

on th

e ac

tivity

of e

nzym

es.

• Sk

ill: E

xper

imen

tal i

nves

tigat

ion

of a

fact

or a

ffec

ting

enzy

me

activ

ity.

(Pra

ctic

al 3

)

Gui

danc

e:

• La

ctas

e ca

n be

imm

obili

zed

in a

lgin

ate

bead

s an

d ex

perim

ents

can

then

be

carr

ied

out i

n w

hich

the

lact

ose

in m

ilk is

hyd

roly

sed.

• St

uden

ts s

houl

d be

abl

e to

ske

tch

grap

hs to

sho

w th

e ex

pect

ed e

ffec

ts o

f te

mpe

ratu

re, p

H a

nd s

ubst

rate

con

cent

ratio

n on

the

activ

ity o

f enz

ymes

. Th

ey s

houl

d be

abl

e to

exp

lain

the

patt

erns

or t

rend

s ap

pare

nt in

thes

e gr

aphs

.

Theo

ry o

f kno

wle

dge:

• D

evel

opm

ent o

f som

e te

chni

ques

ben

efits

par

ticul

ar h

uman

pop

ulat

ions

m

ore

than

oth

ers.

For

exa

mpl

e, th

e de

velo

pmen

t of l

acto

se-f

ree

milk

av

aila

ble

in E

urop

e an

d N

orth

Am

eric

a w

ould

hav

e gr

eate

r ben

efit

in A

fric

a/A

sia

whe

re la

ctos

e in

tole

ranc

e is

mor

e pr

eval

ent.

The

deve

lopm

ent o

f te

chni

ques

requ

ires

finan

cial

inve

stm

ent.

Shou

ld k

now

ledg

e be

sha

red

whe

n te

chni

ques

dev

elop

ed in

one

par

t of t

he w

orld

are

mor

e ap

plic

able

in

anot

her?

Uti

lizat

ion:

• En

zym

es a

re e

xten

sive

ly u

sed

in in

dust

ry fo

r the

pro

duct

ion

of it

ems

from

fr

uit j

uice

to w

ashi

ng p

owde

r.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

8 A

HL

Met

abol

ism

, cel

l res

pira

tion

and

phot

osyn

thes

is

Topic 2: Molecular biology

Biology guide 43

Esse

ntia

l ide

a: T

he s

truc

ture

of D

NA

allo

ws

effic

ient

sto

rage

of g

enet

ic in

form

atio

n.

2.6

Stru

ctur

e of

DN

A a

nd R

NA

Nat

ure

of s

cien

ce:

Usi

ng m

odel

s as

repr

esen

tatio

n of

the

real

wor

ld—

Cric

k an

d W

atso

n us

ed m

odel

mak

ing

to d

isco

ver t

he s

truc

ture

of D

NA

. (1.

10)

Und

erst

andi

ngs:

• Th

e nu

clei

c ac

ids

DN

A a

nd R

NA

are

pol

ymer

s of

nuc

leot

ides

.

• D

NA

diff

ers

from

RN

A in

the

num

ber o

f str

ands

pre

sent

, the

bas

e co

mpo

sitio

n an

d th

e ty

pe o

f pen

tose

.

• D

NA

is a

dou

ble

helix

mad

e of

two

antip

aral

lel s

tran

ds o

f nuc

leot

ides

link

ed

by h

ydro

gen

bond

ing

betw

een

com

plem

enta

ry b

ase

pairs

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

rick

and

Wat

son’

s el

ucid

atio

n of

the

stru

ctur

e of

DN

A u

sing

m

odel

mak

ing.

• Sk

ill: D

raw

ing

sim

ple

diag

ram

s of

the

stru

ctur

e of

sin

gle

nucl

eotid

es a

nd

of D

NA

and

RN

A, u

sing

circ

les,

pen

tago

ns a

nd re

ctan

gles

to re

pres

ent

phos

phat

es, p

ento

ses

and

base

s.

Gui

danc

e:

• In

dia

gram

s of

DN

A s

truc

ture

, the

hel

ical

sha

pe d

oes

not n

eed

to b

e sh

own,

bu

t the

two

stra

nds

shou

ld b

e sh

own

antip

aral

lel.

Ade

nine

sho

uld

be s

how

n pa

ired

with

thym

ine

and

guan

ine

with

cyt

osin

e, b

ut th

e re

lativ

e le

ngth

s of

th

e pu

rine

and

pyrim

idin

e ba

ses

do n

ot n

eed

to b

e re

calle

d, n

or th

e nu

mbe

rs

of h

ydro

gen

bond

s be

twee

n th

e ba

se p

airs

.

Theo

ry o

f kno

wle

dge:

• Th

e st

ory

of th

e el

ucid

atio

n of

the

stru

ctur

e of

DN

A il

lust

rate

s th

at

coop

erat

ion

and

colla

bora

tion

amon

g sc

ient

ists

exi

sts

alon

gsid

e co

mpe

titio

n be

twee

n re

sear

ch g

roup

s. T

o w

hat e

xten

t is

rese

arch

in s

ecre

t ‘an

ti-sc

ient

ific’

? W

hat i

s th

e re

latio

nshi

p be

twee

n sh

ared

and

per

sona

l kno

wle

dge

in th

e na

tura

l sci

ence

s?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

2.2

Wat

er

Topi

c 3.

5 G

enet

ic m

odifi

catio

n an

d bi

otec

hnol

ogy

Topi

c 7

Nuc

leic

aci

ds

Topic 2: Molecular biology

Biology guide44

Esse

ntia

l Ide

a: G

enet

ic in

form

atio

n in

DN

A c

an b

e ac

cura

tely

cop

ied

and

can

be tr

ansl

ated

to m

ake

the

prot

eins

nee

ded

by th

e ce

ll.

2.7

DN

A re

plic

atio

n, tr

ansc

ript

ion

and

tran

slat

ion

Nat

ure

of s

cien

ce:

Obt

aini

ng e

vide

nce

for s

cien

tific

theo

ries—

Mes

elso

n an

d St

ahl o

btai

ned

evid

ence

for t

he s

emi-c

onse

rvat

ive

repl

icat

ion

of D

NA

. (1.

8)

Und

erst

andi

ngs:

• Th

e re

plic

atio

n of

DN

A is

sem

i-con

serv

ativ

e an

d de

pend

s on

com

plem

enta

ry

base

pai

ring.

• H

elic

ase

unw

inds

the

doub

le h

elix

and

sep

arat

es th

e tw

o st

rand

s by

bre

akin

g hy

drog

en b

onds

.

• D

NA

pol

ymer

ase

links

nuc

leot

ides

toge

ther

to fo

rm a

new

str

and,

usi

ng th

e pr

e-ex

istin

g st

rand

as

a te

mpl

ate.

• Tr

ansc

riptio

n is

the

synt

hesi

s of

mRN

A c

opie

d fr

om th

e D

NA

bas

e se

quen

ces

by R

NA

pol

ymer

ase.

• Tr

ansl

atio

n is

the

synt

hesi

s of

pol

ypep

tides

on

ribos

omes

.

• Th

e am

ino

acid

seq

uenc

e of

pol

ypep

tides

is d

eter

min

ed b

y m

RNA

acc

ordi

ng

to th

e ge

netic

cod

e.

• Co

dons

of t

hree

bas

es o

n m

RNA

cor

resp

ond

to o

ne a

min

o ac

id in

a

poly

pept

ide.

• Tr

ansl

atio

n de

pend

s on

com

plem

enta

ry b

ase

pairi

ng b

etw

een

codo

ns o

n m

RNA

and

ant

icod

ons

on tR

NA

.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

se o

f Taq

DN

A p

olym

eras

e to

pro

duce

mul

tiple

cop

ies

of D

NA

ra

pidl

y by

the

poly

mer

ase

chai

n re

actio

n (P

CR).

• A

pplic

atio

n: P

rodu

ctio

n of

hum

an in

sulin

in b

acte

ria a

s an

exa

mpl

e of

the

univ

ersa

lity

of th

e ge

netic

cod

e al

low

ing

gene

tran

sfer

bet

wee

n sp

ecie

s.

• Sk

ill: U

se a

tabl

e of

the

gene

tic c

ode

to d

educ

e w

hich

cod

on(s

) cor

resp

onds

to

whi

ch a

min

o ac

id.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

3.5

Gen

etic

mod

ifica

tion

and

biot

echn

olog

yTo

pic

7.2

Tran

scrip

tion

and

gene

exp

ress

ion

Topi

c 7.

3 Tr

ansl

atio

n

Aim

s:

• A

im 8

: The

re a

re e

thic

al im

plic

atio

ns in

alte

ring

the

geno

me

of a

n or

gani

sm

in o

rder

to p

rodu

ce p

rote

ins

for m

edic

al u

se in

hum

ans.

Topic 2: Molecular biology

Biology guide 45

2.7

DN

A re

plic

atio

n, tr

ansc

ript

ion

and

tran

slat

ion

• Sk

ill: A

naly

sis

of M

esel

son

and

Stah

l’s re

sults

to o

btai

n su

ppor

t for

the

theo

ry

of s

emi-c

onse

rvat

ive

repl

icat

ion

of D

NA

.

• Sk

ill: U

se a

tabl

e of

mRN

A c

odon

s an

d th

eir c

orre

spon

ding

am

ino

acid

s to

ded

uce

the

sequ

ence

of a

min

o ac

ids

code

d by

a s

hort

mRN

A s

tran

d of

kn

own

base

seq

uenc

e.

• Sk

ill: D

educ

ing

the

DN

A b

ase

sequ

ence

for t

he m

RNA

str

and.

Gui

danc

e:

• Th

e di

ffer

ent t

ypes

of D

NA

pol

ymer

ase

do n

ot n

eed

to b

e di

stin

guis

hed.

Topic 2: Molecular biology

Biology guide46

Esse

ntia

l ide

a: C

ell r

espi

ratio

n su

pplie

s en

ergy

for t

he fu

nctio

ns o

f life

.

2.8

Cell

resp

irat

ion

Nat

ure

of s

cien

ce:

Ass

essi

ng th

e et

hics

of s

cien

tific

rese

arch

—th

e us

e of

inve

rteb

rate

s in

resp

irom

eter

exp

erim

ents

has

eth

ical

impl

icat

ions

. (4.

5)

Und

erst

andi

ngs:

• Ce

ll re

spira

tion

is th

e co

ntro

lled

rele

ase

of e

nerg

y fr

om o

rgan

ic c

ompo

unds

to

pro

duce

ATP

.

• AT

P fr

om c

ell r

espi

ratio

n is

imm

edia

tely

ava

ilabl

e as

a s

ourc

e of

ene

rgy

in th

e ce

ll.

• A

naer

obic

cel

l res

pira

tion

give

s a

smal

l yie

ld o

f ATP

from

glu

cose

.

• A

erob

ic c

ell r

espi

ratio

n re

quire

s ox

ygen

and

giv

es a

larg

e yi

eld

of A

TP fr

om

gluc

ose.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

se o

f ana

erob

ic c

ell r

espi

ratio

n in

yea

sts

to p

rodu

ce e

than

ol

and

carb

on d

ioxi

de in

bak

ing.

• A

pplic

atio

n: L

acta

te p

rodu

ctio

n in

hum

ans

whe

n an

aero

bic

resp

iratio

n is

us

ed to

max

imiz

e th

e po

wer

of m

uscl

e co

ntra

ctio

ns.

• Sk

ill: A

naly

sis

of re

sults

from

exp

erim

ents

invo

lvin

g m

easu

rem

ent o

f re

spira

tion

rate

s in

ger

min

atin

g se

eds

or in

vert

ebra

tes

usin

g a

resp

irom

eter

.

Gui

danc

e:

• D

etai

ls o

f the

met

abol

ic p

athw

ays

of c

ell r

espi

ratio

n ar

e no

t nee

ded

but t

he

subs

trat

es a

nd fi

nal w

aste

pro

duct

s sh

ould

be

know

n.

• Th

ere

are

man

y si

mpl

e re

spiro

met

ers

whi

ch c

ould

be

used

. Stu

dent

s ar

e ex

pect

ed to

kno

w th

at a

n al

kali

is u

sed

to a

bsor

b CO

2, so

redu

ctio

ns in

vo

lum

e ar

e du

e to

oxy

gen

use.

Tem

pera

ture

sho

uld

be k

ept c

onst

ant t

o av

oid

volu

me

chan

ges

due

to te

mpe

ratu

re fl

uctu

atio

ns.

Aim

s:

• A

im 8

: The

eth

ics

of th

e us

e of

ani

mal

s in

exp

erim

ents

cou

ld b

e di

scus

sed

in re

latio

n to

resp

irom

eter

exp

erim

ents

. Lar

ge-s

cale

use

of f

ood

plan

ts fo

r bi

ofue

ls a

nd th

e re

sulti

ng im

pact

on

food

pric

es h

as e

thic

al im

plic

atio

ns.

Topic 2: Molecular biology

Biology guide 47

Esse

ntia

l ide

a: P

hoto

synt

hesi

s us

es th

e en

ergy

in s

unlig

ht to

pro

duce

the

chem

ical

ene

rgy

need

ed fo

r life

.

2.9

Phot

osyn

thes

is

Nat

ure

of s

cien

ce:

Expe

rimen

tal d

esig

n—co

ntro

lling

rele

vant

var

iabl

es in

pho

tosy

nthe

sis

expe

rimen

ts is

ess

entia

l. (3

.1)

Und

erst

andi

ngs:

• Ph

otos

ynth

esis

is th

e pr

oduc

tion

of c

arbo

n co

mpo

unds

in c

ells

usi

ng li

ght

ener

gy.

• Vi

sibl

e lig

ht h

as a

rang

e of

wav

elen

gths

with

vio

let t

he s

hort

est w

avel

engt

h an

d re

d th

e lo

nges

t.

• Ch

loro

phyl

l abs

orbs

red

and

blue

ligh

t mos

t eff

ectiv

ely

and

refle

cts

gree

n lig

ht m

ore

than

oth

er c

olou

rs.

• O

xyge

n is

pro

duce

d in

pho

tosy

nthe

sis

from

the

phot

olys

is o

f wat

er.

• En

ergy

is n

eede

d to

pro

duce

car

bohy

drat

es a

nd o

ther

car

bon

com

poun

ds

from

car

bon

diox

ide.

• Te

mpe

ratu

re, l

ight

inte

nsity

and

car

bon

diox

ide

conc

entr

atio

n ar

e po

ssib

le

limiti

ng fa

ctor

s on

the

rate

of p

hoto

synt

hesi

s.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

hang

es to

the

Eart

h’s

atm

osph

ere,

oce

ans

and

rock

dep

ositi

on

due

to p

hoto

synt

hesi

s.

• Sk

ill: D

raw

ing

an a

bsor

ptio

n sp

ectr

um fo

r chl

orop

hyll

and

an a

ctio

n sp

ectr

um fo

r pho

tosy

nthe

sis.

• Sk

ill: D

esig

n of

exp

erim

ents

to in

vest

igat

e th

e ef

fect

of l

imiti

ng fa

ctor

s on

ph

otos

ynth

esis

.

• Sk

ill: S

epar

atio

n of

pho

tosy

nthe

tic p

igm

ents

by

chro

mat

ogra

ph. (

Prac

tical

4)

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

2.5

Enzy

mes

Topic 2: Molecular biology

Biology guide48

2.9

Phot

osyn

thes

is

Gui

danc

e:

• St

uden

ts s

houl

d kn

ow th

at v

isib

le li

ght h

as w

avel

engt

hs b

etw

een

400

and

700

nano

met

res,

but

they

are

not

exp

ecte

d to

reca

ll th

e w

avel

engt

hs o

f sp

ecifi

c co

lour

s of

ligh

t.

• W

ater

free

of d

isso

lved

car

bon

diox

ide

for p

hoto

synt

hesi

s ex

perim

ents

can

be

pro

duce

d by

boi

ling

and

cool

ing

wat

er.

• Pa

per c

hrom

atog

raph

y ca

n be

use

d to

sep

arat

e ph

otos

ynth

etic

pig

men

ts b

ut

thin

laye

r chr

omat

ogra

phy

give

s be

tter

resu

lts.

49Biology guide 49

Core Topi

c 3:

Gen

etic

s 15

hou

rs

Esse

ntia

l ide

a: E

very

livi

ng o

rgan

ism

inhe

rits

a bl

uepr

int f

or li

fe fr

om it

s pa

rent

s.

3.1

Gen

es

Nat

ure

of s

cien

ce:

Dev

elop

men

ts in

sci

entif

ic re

sear

ch fo

llow

impr

ovem

ents

in te

chno

logy

—ge

ne s

eque

ncer

s ar

e us

ed fo

r the

seq

uenc

ing

of g

enes

. (1.

8)

Und

erst

andi

ngs:

• A

gen

e is

a h

erita

ble

fact

or th

at c

onsi

sts

of a

leng

th o

f DN

A a

nd in

fluen

ces

a sp

ecifi

c ch

arac

teris

tic.

• A

gen

e oc

cupi

es a

spe

cific

pos

ition

on

a ch

rom

osom

e.

• Th

e va

rious

spe

cific

form

s of

a g

ene

are

alle

les.

• A

llele

s di

ffer

from

eac

h ot

her b

y on

e or

onl

y a

few

bas

es.

• N

ew a

llele

s ar

e fo

rmed

by

mut

atio

n.

• Th

e ge

nom

e is

the

who

le o

f the

gen

etic

info

rmat

ion

of a

n or

gani

sm.

• Th

e en

tire

base

seq

uenc

e of

hum

an g

enes

was

seq

uenc

ed in

the

Hum

an

Gen

ome

Proj

ect.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: T

he c

ause

s of

sic

kle

cell

anem

ia, i

nclu

ding

a b

ase

subs

titut

ion

mut

atio

n, a

cha

nge

to th

e ba

se s

eque

nce

of m

RNA

tran

scrib

ed fr

om it

and

a

chan

ge to

the

sequ

ence

of a

pol

ypep

tide

in h

emog

lobi

n.

• A

pplic

atio

n: C

ompa

rison

of t

he n

umbe

r of g

enes

in h

uman

s w

ith o

ther

sp

ecie

s.

• Sk

ill: U

se o

f a d

atab

ase

to d

eter

min

e di

ffer

ence

s in

the

base

seq

uenc

e of

a

gene

in tw

o sp

ecie

s.

Inte

rnat

iona

l-m

inde

dnes

s:

• Se

quen

cing

of t

he h

uman

gen

ome

show

s th

at a

ll hu

man

s sh

are

the

vast

m

ajor

ity o

f the

ir ba

se s

eque

nces

but

als

o th

at th

ere

are

man

y si

ngle

nu

cleo

tide

poly

mor

phis

ms

that

con

trib

ute

to h

uman

div

ersi

ty.

Theo

ry o

f kno

wle

dge:

• Th

ere

is a

link

bet

wee

n si

ckle

cel

l ane

mia

and

pre

vale

nce

of m

alar

ia. H

ow c

an

we

know

whe

ther

ther

e is

a c

ausa

l lin

k in

suc

h ca

ses

or s

impl

y a

corr

elat

ion?

Aim

s:

• A

im 7

: The

use

of a

dat

abas

e to

com

pare

DN

A b

ase

sequ

ence

s.

• A

im 8

: Eth

ics

of p

aten

ting

hum

an g

enes

.

Topic 3: Genetics

Biology guide50

3.1

Gen

es

Gui

danc

e:

• St

uden

ts s

houl

d be

abl

e to

reca

ll on

e sp

ecifi

c ba

se s

ubst

itutio

n th

at c

ause

s gl

utam

ic a

cid

to b

e su

bstit

uted

by

valin

e as

the

sixt

h am

ino

acid

in th

e he

mog

lobi

n po

lype

ptid

e.

• Th

e nu

mbe

r of g

enes

in a

spe

cies

sho

uld

not b

e re

ferr

ed to

as

geno

me

size

as

this

term

is u

sed

for t

he to

tal a

mou

nt o

f DN

A. A

t lea

st o

ne p

lant

and

one

ba

cter

ium

sho

uld

be in

clud

ed in

the

com

paris

on a

nd a

t lea

st o

ne s

peci

es

with

mor

e ge

nes

and

one

with

few

er g

enes

than

a h

uman

.

• Th

e G

enba

nk®

data

base

can

be

used

to s

earc

h fo

r DN

A b

ase

sequ

ence

s. T

he

cyto

chro

me

C ge

ne s

eque

nce

is a

vaila

ble

for m

any

diff

eren

t org

anis

ms

and

is o

f par

ticul

ar in

tere

st b

ecau

se o

f its

use

in re

clas

sify

ing

orga

nism

s in

to th

ree

dom

ains

.

• D

elet

ions

, ins

ertio

ns a

nd fr

ame

shift

mut

atio

ns d

o no

t nee

d to

be

incl

uded

.

Topic 3: Genetics

Biology guide 51

Esse

ntia

l ide

a: C

hrom

osom

es c

arry

gen

es in

a li

near

seq

uenc

e th

at is

sha

red

by m

embe

rs o

f a s

peci

es.

3.2

Chro

mos

omes

Nat

ure

of s

cien

ce:

Dev

elop

men

ts in

rese

arch

follo

w im

prov

emen

ts in

tech

niqu

es—

auto

radi

ogra

phy

was

use

d to

est

ablis

h th

e le

ngth

of D

NA

mol

ecul

es in

chr

omos

omes

. (1.

8)

Und

erst

andi

ngs:

• Pr

okar

yote

s ha

ve o

ne c

hrom

osom

e co

nsis

ting

of a

circ

ular

DN

A m

olec

ule.

• So

me

prok

aryo

tes

also

hav

e pl

asm

ids

but e

ukar

yote

s do

not

.

• Eu

kary

ote

chro

mos

omes

are

line

ar D

NA

mol

ecul

es a

ssoc

iate

d w

ith h

isto

ne

prot

eins

.

• In

a e

ukar

yote

spe

cies

ther

e ar

e di

ffer

ent c

hrom

osom

es th

at c

arry

diff

eren

t ge

nes.

• H

omol

ogou

s ch

rom

osom

es c

arry

the

sam

e se

quen

ce o

f gen

es b

ut n

ot

nece

ssar

ily th

e sa

me

alle

les

of th

ose

gene

s.

• D

iplo

id n

ucle

i hav

e pa

irs o

f hom

olog

ous

chro

mos

omes

.

• H

aplo

id n

ucle

i hav

e on

e ch

rom

osom

e of

eac

h pa

ir.

• Th

e nu

mbe

r of c

hrom

osom

es is

a c

hara

cter

istic

feat

ure

of m

embe

rs o

f a

spec

ies.

• A

kar

yogr

am s

how

s th

e ch

rom

osom

es o

f an

orga

nism

in h

omol

ogou

s pa

irs o

f de

crea

sing

leng

th.

• Se

x is

det

erm

ined

by

sex

chro

mos

omes

and

aut

osom

es a

re c

hrom

osom

es

that

do

not d

eter

min

e se

x.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

airn

s’ te

chni

que

for m

easu

ring

the

leng

th o

f DN

A m

olec

ules

by

auto

radi

ogra

phy.

• A

pplic

atio

n: C

ompa

rison

of g

enom

e si

ze in

T2

phag

e, E

sche

richi

a co

li,

Dro

soph

ila m

elan

ogas

ter,

Hom

o sa

pien

s and

Par

is ja

poni

ca.

Inte

rnat

iona

l-m

inde

dnes

s:

• Se

quen

cing

of t

he ri

ce g

enom

e in

volv

ed c

oope

ratio

n be

twee

n bi

olog

ists

in

10 c

ount

ries.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

1.6

Cell

divi

sion

Aim

s:

• A

im 6

: Sta

inin

g ro

ot ti

p sq

uash

es a

nd m

icro

scop

e ex

amin

atio

n of

ch

rom

osom

es is

reco

mm

ende

d bu

t not

obl

igat

ory.

• A

im 7

: Use

of d

atab

ases

to id

entif

y ge

ne lo

ci a

nd p

rote

in p

rodu

cts

of g

enes

.

Topic 3: Genetics

Biology guide52

3.2

Chro

mos

omes

• A

pplic

atio

n: C

ompa

rison

of d

iplo

id c

hrom

osom

e nu

mbe

rs o

f Hom

o sa

pien

s, Pa

n tr

oglo

dyte

s, Ca

nis f

amili

aris,

Ory

za sa

tiva,

Par

asca

ris e

quor

um.

• A

pplic

atio

n: U

se o

f kar

yogr

ams

to d

educ

e se

x an

d di

agno

se D

own

synd

rom

e in

hum

ans.

• Sk

ill: U

se o

f dat

abas

es to

iden

tify

the

locu

s of

a h

uman

gen

e an

d its

po

lype

ptid

e pr

oduc

t.

Gui

danc

e:

• Th

e te

rms

kary

otyp

e an

d ka

ryog

ram

hav

e di

ffer

ent m

eani

ngs.

Kar

yoty

pe is

a

prop

erty

of a

cel

l—th

e nu

mbe

r and

type

of c

hrom

osom

es p

rese

nt in

the

nucl

eus,

not

a p

hoto

grap

h or

dia

gram

of t

hem

.

• G

enom

e si

ze is

the

tota

l len

gth

of D

NA

in a

n or

gani

sm. T

he e

xam

ples

of

geno

me

and

chro

mos

ome

num

ber h

ave

been

sel

ecte

d to

allo

w p

oint

s of

in

tere

st to

be

rais

ed.

• Th

e tw

o D

NA

mol

ecul

es fo

rmed

by

DN

A re

plic

atio

n pr

ior t

o ce

ll di

visi

on a

re

cons

ider

ed to

be

sist

er c

hrom

atid

s un

til th

e sp

littin

g of

the

cent

rom

ere

at th

e st

art o

f ana

phas

e. A

fter

this

, the

y ar

e in

divi

dual

chr

omos

omes

.

Topic 3: Genetics

Biology guide 53

Esse

ntia

l ide

a: A

llele

s se

greg

ate

durin

g m

eios

is a

llow

ing

new

com

bina

tions

to b

e fo

rmed

by

the

fusi

on o

f gam

etes

.

3.3

Mei

osis

Nat

ure

of s

cien

ce:

Mak

ing

care

ful o

bser

vatio

ns—

mei

osis

was

dis

cove

red

by m

icro

scop

e ex

amin

atio

n of

div

idin

g ge

rm-li

ne c

ells

. (1.

8)

Und

erst

andi

ngs:

• O

ne d

iplo

id n

ucle

us d

ivid

es b

y m

eios

is to

pro

duce

four

hap

loid

nuc

lei.

• Th

e ha

lvin

g of

the

chro

mos

ome

num

ber a

llow

s a

sexu

al li

fe c

ycle

with

fusi

on

of g

amet

es.

• D

NA

is re

plic

ated

bef

ore

mei

osis

so

that

all

chro

mos

omes

con

sist

of t

wo

sist

er c

hrom

atid

s.

• Th

e ea

rly s

tage

s of

mei

osis

invo

lve

pairi

ng o

f hom

olog

ous

chro

mos

omes

and

cr

ossi

ng o

ver f

ollo

wed

by

cond

ensa

tion.

• O

rient

atio

n of

pai

rs o

f hom

olog

ous

chro

mos

omes

prio

r to

sepa

ratio

n is

ra

ndom

.

• Se

para

tion

of p

airs

of h

omol

ogou

s ch

rom

osom

es in

the

first

div

isio

n of

m

eios

is h

alve

s th

e ch

rom

osom

e nu

mbe

r.

• Cr

ossi

ng o

ver a

nd ra

ndom

orie

ntat

ion

prom

otes

gen

etic

var

iatio

n.

• Fu

sion

of g

amet

es fr

om d

iffer

ent p

aren

ts p

rom

otes

gen

etic

var

iatio

n.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: N

on-d

isju

nctio

n ca

n ca

use

Dow

n sy

ndro

me

and

othe

r ch

rom

osom

e ab

norm

aliti

es.

• A

pplic

atio

n: S

tudi

es s

how

ing

age

of p

aren

ts in

fluen

ces

chan

ces

of n

on-

disj

unct

ion.

Theo

ry o

f kno

wle

dge:

• In

192

2 th

e nu

mbe

r of c

hrom

osom

es c

ount

ed in

a h

uman

cel

l was

48.

Thi

s re

mai

ned

the

esta

blis

hed

num

ber f

or 3

0 ye

ars,

eve

n th

ough

a re

view

of

phot

ogra

phic

evi

denc

e fr

om th

e tim

e cl

early

sho

wed

that

ther

e w

ere

46. F

or

wha

t rea

sons

do

exis

ting

belie

fs c

arry

a c

erta

in in

ertia

?

Uti

lizat

ion:

• A

n un

ders

tand

ing

of k

aryo

type

s ha

s al

low

ed d

iagn

oses

to b

e m

ade

for t

he

purp

oses

of g

enet

ic c

ouns

ellin

g.

Sylla

bus

and

cros

s-cu

rric

ular

link

s: Bi

olog

y

Topi

c 1.

6 Ce

ll di

visi

on

Topi

c 10

.1 M

eios

is

Topi

c 11

.4 S

exua

l rep

rodu

ctio

n

Aim

s:

• A

im 8

: Pre

-nat

al s

cree

ning

for c

hrom

osom

e ab

norm

aliti

es g

ives

an

indi

catio

n of

the

sex

of th

e fe

tus

and

rais

es e

thic

al is

sues

ove

r sel

ectiv

e ab

ortio

n of

fe

mal

e fe

tuse

s in

som

e co

untr

ies.

Topic 3: Genetics

Biology guide54

3.3

Mei

osis

• A

pplic

atio

n: D

escr

iptio

n of

met

hods

use

d to

obt

ain

cells

for k

aryo

type

an

alys

is e

.g. c

horio

nic

villu

s sa

mpl

ing

and

amni

ocen

tesi

s an

d th

e as

soci

ated

ris

ks.

• Sk

ill: D

raw

ing

diag

ram

s to

sho

w th

e st

ages

of m

eios

is re

sulti

ng in

the

form

atio

n of

four

hap

loid

cel

ls.

Gui

danc

e:

• Pr

epar

atio

n of

mic

rosc

ope

slid

es s

how

ing

mei

osis

is c

halle

ngin

g an

d pe

rman

ent s

lides

sho

uld

be a

vaila

ble

in c

ase

no c

ells

in m

eios

is a

re v

isib

le in

te

mpo

rary

mou

nts.

• D

raw

ings

of t

he s

tage

s of

mei

osis

do

not n

eed

to in

clud

e ch

iasm

ata.

• Th

e pr

oces

s of

chi

asm

ata

form

atio

n ne

ed n

ot b

e ex

plai

ned.

Topic 3: Genetics

Biology guide 55

Esse

ntia

l ide

a: T

he in

herit

ance

of g

enes

follo

ws

patt

erns

.

3.4

Inhe

rita

nce

Nat

ure

of s

cien

ce:

Mak

ing

quan

titat

ive

mea

sure

men

ts w

ith re

plic

ates

to e

nsur

e re

liabi

lity.

Men

del’s

gen

etic

cro

sses

with

pea

pla

nts

gene

rate

d nu

mer

ical

dat

a. (3

.2)

Und

erst

andi

ngs:

• M

ende

l dis

cove

red

the

prin

cipl

es o

f inh

erita

nce

with

exp

erim

ents

in w

hich

la

rge

num

bers

of p

ea p

lant

s w

ere

cros

sed.

• G

amet

es a

re h

aplo

id s

o co

ntai

n on

ly o

ne a

llele

of e

ach

gene

.

• Th

e tw

o al

lele

s of

eac

h ge

ne s

epar

ate

into

diff

eren

t hap

loid

dau

ghte

r nuc

lei

durin

g m

eios

is.

• Fu

sion

of g

amet

es re

sults

in d

iplo

id z

ygot

es w

ith tw

o al

lele

s of

eac

h ge

ne

that

may

be

the

sam

e al

lele

or d

iffer

ent a

llele

s.

• D

omin

ant a

llele

s m

ask

the

effe

cts

of re

cess

ive

alle

les

but c

o-do

min

ant a

llele

s ha

ve jo

int e

ffec

ts.

• M

any

gene

tic d

isea

ses

in h

uman

s ar

e du

e to

rece

ssiv

e al

lele

s of

aut

osom

al

gene

s, a

lthou

gh s

ome

gene

tic d

isea

ses

are

due

to d

omin

ant o

r co-

dom

inan

t al

lele

s.

• So

me

gene

tic d

isea

ses

are

sex-

linke

d. T

he p

atte

rn o

f inh

erita

nce

is d

iffer

ent

with

sex

-link

ed g

enes

due

to th

eir l

ocat

ion

on s

ex c

hrom

osom

es.

• M

any

gene

tic d

isea

ses

have

bee

n id

entif

ied

in h

uman

s bu

t mos

t are

ver

y ra

re.

• Ra

diat

ion

and

mut

agen

ic c

hem

ical

s in

crea

se th

e m

utat

ion

rate

and

can

cau

se

gene

tic d

isea

ses

and

canc

er.

Theo

ry o

f kno

wle

dge:

• M

ende

l’s th

eorie

s w

ere

not a

ccep

ted

by th

e sc

ient

ific

com

mun

ity fo

r a lo

ng

time.

Wha

t fac

tors

wou

ld e

ncou

rage

the

acce

ptan

ce o

f new

idea

s by

the

scie

ntifi

c co

mm

unity

?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

1.6

Cell

divi

sion

Aim

s:

• A

im 8

: Soc

ial i

mpl

icat

ions

of d

iagn

osis

of m

utat

ions

, inc

ludi

ng th

e ef

fect

s on

th

e fa

mily

and

stig

mat

izat

ion.

Topic 3: Genetics

Biology guide56

3.4

Inhe

rita

nce

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: In

herit

ance

of A

BO b

lood

gro

ups.

• A

pplic

atio

n: R

ed-g

reen

col

our b

lindn

ess

and

hem

ophi

lia a

s ex

ampl

es o

f sex

-lin

ked

inhe

ritan

ce.

• A

pplic

atio

n: In

herit

ance

of c

ystic

fibr

osis

and

Hun

tingt

on’s

dise

ase.

• A

pplic

atio

n: C

onse

quen

ces

of ra

diat

ion

afte

r nuc

lear

bom

bing

of H

irosh

ima

and

acci

dent

at C

hern

obyl

.

• Sk

ill: C

onst

ruct

ion

of P

unne

tt g

rids

for p

redi

ctin

g th

e ou

tcom

es o

f m

onoh

ybrid

gen

etic

cro

sses

.

• Sk

ill: C

ompa

rison

of p

redi

cted

and

act

ual o

utco

mes

of g

enet

ic c

ross

es u

sing

re

al d

ata.

• Sk

ill: A

naly

sis

of p

edig

ree

char

ts to

ded

uce

the

patt

ern

of in

herit

ance

of

gene

tic d

isea

ses.

Gui

danc

e:

• A

llele

s ca

rrie

d on

X c

hrom

osom

es s

houl

d be

sho

wn

as s

uper

scrip

t let

ters

on

an u

pper

cas

e X,

suc

h as

Xh .

• Th

e ex

pect

ed n

otat

ion

for A

BO b

lood

gro

up a

llele

s is

:

Phen

otyp

eO A B A

B

Gen

otyp

eii IA

IA o

r IAi

IB IB or I

B iIA

IB

Topic 3: Genetics

Biology guide 57

Esse

ntia

l ide

a: B

iolo

gist

s ha

ve d

evel

oped

tech

niqu

es fo

r art

ifici

al m

anip

ulat

ion

of D

NA

, cel

ls a

nd o

rgan

ism

s.

3.5

Gen

etic

mod

ific

atio

n an

d bi

otec

hnol

ogy

Nat

ure

of s

cien

ce:

Ass

essi

ng ri

sks

asso

ciat

ed w

ith s

cien

tific

rese

arch

—sc

ient

ists

att

empt

to a

sses

s th

e ris

ks a

ssoc

iate

d w

ith g

enet

ical

ly m

odifi

ed c

rops

or l

ives

tock

. (4.

8)

Und

erst

andi

ngs:

• G

el e

lect

roph

ores

is is

use

d to

sep

arat

e pr

otei

ns o

r fra

gmen

ts o

f DN

A

acco

rdin

g to

siz

e.

• PC

R ca

n be

use

d to

am

plify

sm

all a

mou

nts

of D

NA

.

• D

NA

pro

filin

g in

volv

es c

ompa

rison

of D

NA

.

• G

enet

ic m

odifi

catio

n is

car

ried

out b

y ge

ne tr

ansf

er b

etw

een

spec

ies.

• Cl

ones

are

gro

ups

of g

enet

ical

ly id

entic

al o

rgan

ism

s, d

eriv

ed fr

om a

sin

gle

orig

inal

par

ent c

ell.

• M

any

plan

t spe

cies

and

som

e an

imal

spe

cies

hav

e na

tura

l met

hods

of

clon

ing.

• A

nim

als

can

be c

lone

d at

the

embr

yo s

tage

by

brea

king

up

the

embr

yo in

to

mor

e th

an o

ne g

roup

of c

ells

.

• M

etho

ds h

ave

been

dev

elop

ed fo

r clo

ning

adu

lt an

imal

s us

ing

diff

eren

tiate

d ce

lls.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: U

se o

f DN

A p

rofil

ing

in p

ater

nity

and

fore

nsic

inve

stig

atio

ns.

• A

pplic

atio

n: G

ene

tran

sfer

to b

acte

ria u

sing

pla

smid

s m

akes

use

of r

estr

ictio

n en

donu

clea

ses

and

DN

A li

gase

.

• A

pplic

atio

n: A

sses

smen

t of t

he p

oten

tial r

isks

and

ben

efits

ass

ocia

ted

with

ge

netic

mod

ifica

tion

of c

rops

.

• A

pplic

atio

n: P

rodu

ctio

n of

clo

ned

embr

yos

prod

uced

by

som

atic

-cel

l nuc

lear

tr

ansf

er.

Theo

ry o

f kno

wle

dge:

• Th

e us

e of

DN

A fo

r sec

urin

g co

nvic

tions

in le

gal c

ases

is w

ell e

stab

lishe

d,

yet e

ven

univ

ersa

lly a

ccep

ted

theo

ries

are

over

turn

ed in

the

light

of n

ew

evid

ence

in s

cien

ce. W

hat c

riter

ia a

re n

eces

sary

for a

sses

sing

the

relia

bilit

y of

ev

iden

ce?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

2.7

DN

A re

plic

atio

n, tr

ansc

riptio

n an

d tr

ansl

atio

n

Aim

s:

• A

im 6

: The

des

ign

of a

root

ing

expe

rimen

t sho

uld

idea

lly le

ad to

the

expe

rimen

t act

ually

bei

ng c

arrie

d ou

t by

stud

ents

.

• A

im 8

: The

eth

ics

of g

enet

ic m

odifi

catio

n co

uld

be d

iscu

ssed

.

Topic 3: Genetics

Biology guide58

3.5

Gen

etic

mod

ific

atio

n an

d bi

otec

hnol

ogy

• Sk

ill: D

esig

n of

an

expe

rimen

t to

asse

ss o

ne fa

ctor

aff

ectin

g th

e ro

otin

g of

st

em-c

uttin

gs.

• Sk

ill: A

naly

sis

of e

xam

ples

of D

NA

pro

files

.

• Sk

ill: A

naly

sis

of d

ata

on ri

sks

to m

onar

ch b

utte

rflie

s of

Bt c

rops

.

Gui

danc

e:

• St

uden

ts s

houl

d be

abl

e to

ded

uce

whe

ther

or n

ot a

man

cou

ld b

e th

e fa

ther

of

a c

hild

from

the

patt

ern

of b

ands

on

a D

NA

pro

file.

• D

olly

can

be

used

as

an e

xam

ple

of s

omat

ic-c

ell t

rans

fer.

• A

pla

nt s

peci

es s

houl

d be

cho

sen

for r

ootin

g ex

perim

ents

that

form

s ro

ots

read

ily in

wat

er o

r a s

olid

med

ium

.

59Biology guide 59

Core Topi

c 4:

Eco

logy

12

hou

rs

Esse

ntia

l ide

a: T

he c

ontin

ued

surv

ival

of l

ivin

g or

gani

sms

incl

udin

g hu

man

s de

pend

s on

sus

tain

able

com

mun

ities

.

4.1

Spec

ies,

com

mun

itie

s an

d ec

osys

tem

s

Nat

ure

of s

cien

ce:

Look

ing

for p

atte

rns,

tren

ds a

nd d

iscr

epan

cies

—pl

ants

and

alg

ae a

re m

ostly

aut

otro

phic

but

som

e ar

e no

t. (3

.1)

Und

erst

andi

ngs:

• Sp

ecie

s ar

e gr

oups

of o

rgan

ism

s th

at c

an p

oten

tially

inte

rbre

ed to

pro

duce

fe

rtile

off

sprin

g.

• M

embe

rs o

f a sp

ecie

s may

be

repr

oduc

tivel

y is

olat

ed in

sepa

rate

pop

ulat

ions

.

• Sp

ecie

s ha

ve e

ither

an

auto

trop

hic

or h

eter

otro

phic

met

hod

of n

utrit

ion

(a

few

spe

cies

hav

e bo

th m

etho

ds).

• Co

nsum

ers

are

hete

rotr

ophs

that

feed

on

livin

g or

gani

sms

by in

gest

ion.

• D

etrit

ivor

es a

re h

eter

otro

phs

that

obt

ain

orga

nic

nut

rient

s fr

om d

etrit

us b

y in

tern

al d

iges

tion.

• Sa

prot

roph

s ar

e he

tero

trop

hs th

at o

btai

n or

gani

c n

utrie

nts

from

dea

d or

gani

sms

by e

xter

nal d

iges

tion.

• A

com

mun

ity is

form

ed b

y po

pula

tions

of d

iffer

ent s

peci

es li

ving

toge

ther

an

d in

tera

ctin

g w

ith e

ach

othe

r.

• A

com

mun

ity fo

rms

an e

cosy

stem

by

its in

tera

ctio

ns w

ith th

e ab

iotic

en

viro

nmen

t.

• Au

totr

ophs

obt

ain

inor

gani

c n

utrie

nts

from

the

abio

tic e

nviro

nmen

t.

• Th

e su

pply

of i

norg

anic

nut

rient

s is

mai

ntai

ned

by n

utrie

nt c

yclin

g.

• Ec

osys

tem

s ha

ve th

e po

tent

ial t

o be

sus

tain

able

ove

r lon

g pe

riods

of t

ime.

Inte

rnat

iona

l-m

inde

dnes

s:

• Th

e ne

ed fo

r sus

tain

abili

ty in

hum

an a

ctiv

ities

cou

ld b

e di

scus

sed

and

the

met

hods

nee

ded

to p

rom

ote

this

.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:G

eogr

aphy

Part

2A

: Fre

sh w

ater

-issu

es a

nd c

onfli

cts

Envi

ronm

enta

l sys

tem

s an

d so

ciet

ies

Topi

c 2.

1 Sp

ecie

s an

d po

pula

tions

Aim

s:

• A

im 6

: It w

ould

be

best

for s

tude

nts

to o

btai

n da

ta fo

r the

chi

-squ

ared

test

th

emse

lves

, to

give

firs

t-ha

nd e

xper

ienc

e of

fiel

d w

ork

tech

niqu

es.

Topic 4: Ecology

Biology guide60

4.1

Spec

ies,

com

mun

itie

s an

d ec

osys

tem

s

App

licat

ions

and

ski

lls:

• Sk

ill: C

lass

ifyin

g sp

ecie

s as

aut

otro

phs,

con

sum

ers,

det

ritiv

ores

or s

apro

trop

hs

from

a k

now

ledg

e of

thei

r mod

e of

nut

ritio

n.

• Sk

ill: S

ettin

g up

seal

ed m

esoc

osm

s to

try

to e

stab

lish

sust

aina

bilit

y. (P

ract

ical

5)

• Sk

ill: T

estin

g fo

r ass

ocia

tion

betw

een

two

spec

ies

usin

g th

e ch

i-squ

ared

test

w

ith d

ata

obta

ined

by

quad

rat s

ampl

ing.

• Sk

ill: R

ecog

nizi

ng a

nd in

terp

retin

g st

atis

tical

sig

nific

ance

.

Gui

danc

e:

• M

esoc

osm

s ca

n be

set

up

in o

pen

tank

s, b

ut s

eale

d gl

ass

vess

els

are

pref

erab

le b

ecau

se e

ntry

and

exi

t of m

atte

r can

be

prev

ente

d bu

t lig

ht c

an

ente

r and

hea

t can

leav

e. A

quat

ic s

yste

ms

are

likel

y to

be

mor

e su

cces

sful

th

an te

rres

tria

l one

s.

• To

obt

ain

data

for t

he c

hi-s

quar

ed te

st, a

n ec

osys

tem

sho

uld

be c

hose

n in

w

hich

one

or m

ore

fact

ors

affe

ctin

g th

e di

strib

utio

n of

the

chos

en s

peci

es

varie

s. S

ampl

ing

shou

ld b

e ba

sed

on ra

ndom

num

bers

. In

each

qua

drat

the

pres

ence

or a

bsen

ce o

f the

cho

sen

spec

ies

shou

ld b

e re

cord

ed.

Topic 4: Ecology

Biology guide 61

Esse

ntia

l ide

a: E

cosy

stem

s re

quire

a c

ontin

uous

sup

ply

of e

nerg

y to

fuel

life

pro

cess

es a

nd to

repl

ace

ener

gy lo

st a

s he

at.

4.2

Ener

gy fl

ow

Nat

ure

of s

cien

ce:

Use

theo

ries

to e

xpla

in n

atur

al p

heno

men

a—th

e co

ncep

t of e

nerg

y flo

w e

xpla

ins

the

limite

d le

ngth

of f

ood

chai

ns. (

2.2)

Und

erst

andi

ngs:

• M

ost e

cosy

stem

s re

ly o

n a

supp

ly o

f ene

rgy

from

sun

light

.

• Li

ght e

nerg

y is

con

vert

ed to

che

mic

al e

nerg

y in

car

bon

com

poun

ds b

y ph

otos

ynth

esis

.

• Ch

emic

al e

nerg

y in

car

bon

com

poun

ds fl

ows

thro

ugh

food

cha

ins

by m

eans

of

feed

ing.

• En

ergy

rele

ased

from

car

bon

com

poun

ds b

y re

spira

tion

is u

sed

in li

ving

or

gani

sms

and

conv

erte

d to

hea

t.

• Li

ving

org

anis

ms

cann

ot c

onve

rt h

eat t

o ot

her f

orm

s of

ene

rgy.

• H

eat i

s lo

st fr

om e

cosy

stem

s.

• En

ergy

loss

es b

etw

een

trop

hic

leve

ls re

stric

t the

leng

th o

f foo

d ch

ains

and

th

e bi

omas

s of

hig

her t

roph

ic le

vels

.

App

licat

ions

and

ski

lls:

• Sk

ill: Q

uant

itativ

e re

pres

enta

tions

of e

nerg

y flo

w u

sing

pyr

amid

s of

ene

rgy.

Gui

danc

e:

• Py

ram

ids

of n

umbe

r and

bio

mas

s ar

e no

t req

uire

d. S

tude

nts

shou

ld b

e cl

ear

that

bio

mas

s in

terr

estr

ial e

cosy

stem

s di

min

ishe

s w

ith e

nerg

y al

ong

food

ch

ains

due

to lo

ss o

f car

bon

diox

ide,

wat

er a

nd o

ther

was

te p

rodu

cts,

suc

h as

ur

ea.

Inte

rnat

iona

l-m

inde

dnes

s:

• Th

e en

erge

tics

of fo

od c

hain

s is

a fa

ctor

in th

e ef

ficie

ncy

of fo

od p

rodu

ctio

n fo

r the

alle

viat

ion

of w

orld

hun

ger.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

2.8

Cell

resp

iratio

nTo

pic

2.9

Phot

osyn

thes

isPh

ysic

sTo

pic

2.3

Wor

k, e

nerg

y an

d po

wer

Topi

c B.

2 Th

erm

odyn

amic

sEn

viro

nmen

tal s

yste

ms

and

soci

etie

sTo

pic

2.3

Flow

s of

ene

rgy

and

mat

ter

Topic 4: Ecology

Biology guide62

4.2

Ener

gy fl

ow

• Py

ram

ids

of e

nerg

y sh

ould

be

draw

n to

sca

le a

nd s

houl

d be

ste

pped

, not

tr

iang

ular

. The

term

s pr

oduc

er, f

irst c

onsu

mer

and

sec

ond

cons

umer

and

so

on s

houl

d be

use

d, ra

ther

than

firs

t tro

phic

leve

l, se

cond

trop

hic

leve

l and

so

on.

• Th

e di

stin

ctio

n be

twee

n en

ergy

flow

in e

cosy

stem

s an

d cy

clin

g of

inor

gani

c nu

trie

nts

shou

ld b

e st

ress

ed. S

tude

nts

shou

ld u

nder

stan

d th

at th

ere

is a

co

ntin

uous

but

var

iabl

e su

pply

of e

nerg

y in

the

form

of s

unlig

ht b

ut th

at th

e su

pply

of n

utrie

nts

in a

n ec

osys

tem

is fi

nite

and

lim

ited.

Topic 4: Ecology

Biology guide 63

Esse

ntia

l ide

a: C

ontin

ued

avai

labi

lity

of c

arbo

n in

eco

syst

ems

depe

nds

on c

arbo

n cy

clin

g.

4.3

Carb

on c

yclin

g

Nat

ure

of s

cien

ce:

Mak

ing

accu

rate

, qua

ntita

tive

mea

sure

men

ts—

it is

impo

rtan

t to

obta

in re

liabl

e da

ta o

n th

e co

ncen

trat

ion

of c

arbo

n di

oxid

e an

d m

etha

ne in

the

atm

osph

ere.

(3.1)

Und

erst

andi

ngs:

• Au

totr

ophs

con

vert

car

bon

diox

ide

into

car

bohy

drat

es a

nd o

ther

car

bon

com

poun

ds.

• In

aqu

atic

eco

syst

ems

carb

on is

pre

sent

as

diss

olve

d ca

rbon

dio

xide

and

hy

drog

enca

rbon

ate

ions

.

• Ca

rbon

dio

xide

diff

uses

from

the

atm

osph

ere

or w

ater

into

aut

otro

phs.

• Ca

rbon

dio

xide

is p

rodu

ced

by re

spira

tion

and

diff

uses

out

of o

rgan

ism

s in

to

wat

er o

r the

atm

osph

ere.

• M

etha

ne is

pro

duce

d fr

om o

rgan

ic m

atte

r in

anae

robi

c co

nditi

ons

by

met

hano

geni

c ar

chae

ans

and

som

e di

ffus

es in

to th

e at

mos

pher

e or

ac

cum

ulat

es in

the

grou

nd.

• M

etha

ne is

oxi

dize

d to

car

bon

diox

ide

and

wat

er in

the

atm

osph

ere.

• Pe

at fo

rms

whe

n or

gani

c m

atte

r is

not f

ully

dec

ompo

sed

beca

use

of a

cidi

c an

d/or

ana

erob

ic c

ondi

tions

in w

ater

logg

ed s

oils

.

• Pa

rtia

lly d

ecom

pose

d or

gani

c m

atte

r fro

m p

ast g

eolo

gica

l era

s w

as

conv

erte

d ei

ther

into

coa

l or i

nto

oil a

nd g

as th

at a

ccum

ulat

e in

por

ous

rock

s.

• Ca

rbon

dio

xide

is p

rodu

ced

by th

e co

mbu

stio

n of

bio

mas

s an

d fo

ssili

zed

orga

nic

mat

ter.

• A

nim

als

such

as

reef

-bui

ldin

g co

rals

and

mol

lusc

a ha

ve h

ard

part

s th

at a

re

com

pose

d of

cal

cium

car

bona

te a

nd c

an b

ecom

e fo

ssili

zed

in li

mes

tone

.

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Ph

ysic

sTo

pic

8.1

Ener

gy s

ourc

esCh

emis

try

Topi

c C

.2 F

ossi

l fue

lsTo

pic

C.5

Env

ironm

enta

l im

pact

—gl

obal

war

min

g

Aim

s:

• A

im 8

: The

eth

ical

impl

icat

ions

of d

iver

ting

crop

s su

ch a

s m

aize

from

a fo

od

to a

fuel

cro

p co

uld

be c

onsi

dere

d.

Topic 4: Ecology

Biology guide64

4.3

Carb

on c

yclin

g

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: E

stim

atio

n of

car

bon

fluxe

s du

e to

pro

cess

es in

the

carb

on c

ycle

.

• A

pplic

atio

n: A

naly

sis

of d

ata

from

air

mon

itorin

g st

atio

ns to

exp

lain

ann

ual

fluct

uatio

ns.

• Sk

ill: C

onst

ruct

a d

iagr

am o

f the

car

bon

cycl

e.

Gui

danc

e:

• Ca

rbon

flux

es s

houl

d be

mea

sure

d in

gig

aton

nes.

Topic 4: Ecology

Biology guide 65

Esse

ntia

l ide

a: C

once

ntra

tions

of g

ases

in th

e at

mos

pher

e af

fect

clim

ates

exp

erie

nced

at t

he E

arth

’s su

rfac

e.

4.4

Clim

ate

chan

ge

Nat

ure

of s

cien

ce:

Ass

essi

ng c

laim

s—as

sess

men

t of t

he c

laim

s th

at h

uman

act

iviti

es a

re p

rodu

cing

clim

ate

chan

ge. (

5.2)

Und

erst

andi

ngs:

• Ca

rbon

dio

xide

and

wat

er v

apou

r are

the

mos

t sig

nific

ant g

reen

hous

e ga

ses.

• O

ther

gas

es in

clud

ing

met

hane

and

nitr

ogen

oxi

des

have

less

impa

ct.

• Th

e im

pact

of a

gas

dep

ends

on

its a

bilit

y to

abs

orb

long

wav

e ra

diat

ion

as

wel

l as

on it

s co

ncen

trat

ion

in th

e at

mos

pher

e.

• Th

e w

arm

ed E

arth

em

its lo

nger

wav

elen

gth

radi

atio

n (h

eat).

• Lo

nger

wav

e ra

diat

ion

is a

bsor

bed

by g

reen

hous

e ga

ses

that

reta

in th

e he

at

in th

e at

mos

pher

e.

• G

loba

l tem

pera

ture

s an

d cl

imat

e pa

tter

ns a

re in

fluen

ced

by c

once

ntra

tions

of

gre

enho

use

gase

s.

• Th

ere

is a

cor

rela

tion

betw

een

risin

g at

mos

pher

ic c

once

ntra

tions

of c

arbo

n di

oxid

e si

nce

the

star

t of t

he in

dust

rial r

evol

utio

n 20

0 ye

ars

ago

and

aver

age

glob

al te

mpe

ratu

res.

• Re

cent

incr

ease

s in

atm

osph

eric

car

bon

diox

ide

are

larg

ely

due

to in

crea

ses

in th

e co

mbu

stio

n of

foss

ilize

d or

gani

c m

atte

r.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: T

hrea

ts to

cor

al re

efs

from

incr

easi

ng c

once

ntra

tions

of d

isso

lved

ca

rbon

dio

xide

.

• A

pplic

atio

n: C

orre

latio

ns b

etw

een

glob

al te

mpe

ratu

res

and

carb

on d

ioxi

de

conc

entr

atio

ns o

n Ea

rth.

• A

pplic

atio

n: E

valu

atin

g cl

aim

s th

at h

uman

act

iviti

es a

re n

ot c

ausi

ng c

limat

e ch

ange

.

Inte

rnat

iona

l-m

inde

dnes

s:

• Re

leas

e of

gre

enho

use

gase

s oc

curs

loca

lly b

ut h

as a

glo

bal i

mpa

ct, s

o in

tern

atio

nal c

oope

ratio

n to

redu

ce e

mis

sion

s is

ess

entia

l.

Theo

ry o

f kno

wle

dge:

• Th

e pr

ecau

tiona

ry p

rinci

ple

is m

eant

to g

uide

dec

isio

n-m

akin

g in

con

ditio

ns

whe

re a

lack

of c

erta

inty

exi

sts.

Is c

erta

inty

eve

r pos

sibl

e in

the

natu

ral

scie

nces

?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Ph

ysic

sTo

pic

8.2

Ther

mal

ene

rgy

tran

sfer

Geo

grap

hyPa

rt 1

.3 P

atte

rns

in e

nviro

nmen

tal q

ualit

y an

d su

stai

nabi

lity/

Atm

osph

ere

and

chan

geEn

viro

nmen

tal s

yste

ms

and

soci

etie

sTo

pic

7.2

Clim

ate

chan

ge—

caus

es a

nd im

pact

s

Aim

s:

• A

im 7

: Dat

abas

es c

an b

e us

ed to

ana

lyse

con

cent

ratio

ns o

f gre

enho

use

gase

s.

• A

im 8

: The

re a

re in

tere

stin

g pa

ralle

ls b

etw

een

hum

ans

that

are

unw

illin

g to

re

duce

thei

r car

bon

foot

prin

t and

che

atin

g in

soc

ial a

nim

als.

Whe

n th

e le

vel

of c

heat

ing

rises

abo

ve a

cer

tain

leve

l, so

cial

beh

avio

ur b

reak

s do

wn.

Topic 4: Ecology

Biology guide66

4.4

Clim

ate

chan

ge

Gui

danc

e:

• Ca

rbon

dio

xide

, met

hane

and

wat

er v

apou

r sho

uld

be in

clud

ed in

di

scus

sion

s.

• Th

e ha

rmfu

l con

sequ

ence

s of

ozo

ne d

eple

tion

do n

ot n

eed

to b

e di

scus

sed

and

it sh

ould

be

mad

e cl

ear t

hat o

zone

dep

letio

n is

not

the

caus

e of

the

enha

nced

gre

enho

use

effe

ct.

67Biology guide 67

Core Topi

c 5:

Evo

lutio

n an

d bi

odiv

ersi

ty

12 h

ours

Esse

ntia

l ide

a: T

here

is o

verw

helm

ing

evid

ence

for t

he e

volu

tion

of li

fe o

n Ea

rth.

5.1

Evi

denc

e fo

r evo

luti

on

Nat

ure

of s

cien

ce:

Look

ing

for p

atte

rns,

tren

ds a

nd d

iscr

epan

cies

—th

ere

are

com

mon

feat

ures

in th

e bo

ne s

truc

ture

of v

erte

brat

e lim

bs d

espi

te th

eir v

arie

d us

e. (3

.1)

Und

erst

andi

ngs:

• Ev

olut

ion

occu

rs w

hen

herit

able

cha

ract

eris

tics

of a

spe

cies

cha

nge.

• Th

e fo

ssil

reco

rd p

rovi

des

evid

ence

for e

volu

tion.

• Se

lect

ive

bree

ding

of d

omes

ticat

ed a

nim

als

show

s th

at a

rtifi

cial

sel

ectio

n ca

n ca

use

evol

utio

n.

• Ev

olut

ion

of h

omol

ogou

s st

ruct

ures

by

adap

tive

radi

atio

n ex

plai

ns

sim

ilarit

ies

in s

truc

ture

whe

n th

ere

are

diff

eren

ces

in fu

nctio

n.

• Po

pula

tions

of a

spe

cies

can

gra

dual

ly d

iver

ge in

to s

epar

ate

spec

ies

by

evol

utio

n.

• Co

ntin

uous

var

iatio

n ac

ross

the

geog

raph

ical

rang

e of

rela

ted

popu

latio

ns

mat

ches

the

conc

ept o

f gra

dual

div

erge

nce.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: D

evel

opm

ent o

f mel

anis

tic in

sect

s in

pol

lute

d ar

eas.

• A

pplic

atio

n: C

ompa

rison

of t

he p

enta

dact

yl li

mb

of m

amm

als,

bird

s,

amph

ibia

ns a

nd re

ptile

s w

ith d

iffer

ent m

etho

ds o

f loc

omot

ion.

Theo

ry o

f kno

wle

dge:

• Ev

olut

iona

ry h

isto

ry is

an

espe

cial

ly c

halle

ngin

g ar

ea o

f sci

ence

bec

ause

ex

perim

ents

can

not b

e pe

rfor

med

to e

stab

lish

past

eve

nts

or th

eir c

ause

s.

Ther

e ar

e no

neth

eles

s sc

ient

ific

met

hods

of e

stab

lishi

ng b

eyon

d re

ason

able

do

ubt w

hat h

appe

ned

in s

ome

case

s. H

ow d

o th

ese

met

hods

com

pare

to

thos

e us

ed b

y hi

stor

ians

to re

cons

truc

t the

pas

t?

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Ph

ysic

sTo

pic

7.1 D

iscr

ete

ener

gy a

nd ra

dioa

ctiv

ityG

eogr

aphy

Pa

rt 1

.3 P

atte

rns

in e

nviro

nmen

tal q

ualit

y an

d su

stai

nabi

lity/

Biod

iver

sity

and

ch

ange

Envi

ronm

enta

l sys

tem

s an

d so

ciet

ies

Topi

c 4

Biod

iver

sity

in e

cosy

stem

s

Topic 5: Evolution and biodiversity

Biology guide68

Esse

ntia

l ide

a: T

he d

iver

sity

of l

ife h

as e

volv

ed a

nd c

ontin

ues

to e

volv

e by

nat

ural

sel

ectio

n.

5.2

Nat

ural

sel

ecti

on

Nat

ure

of s

cien

ce:

Use

theo

ries

to e

xpla

in n

atur

al p

heno

men

a—th

e th

eory

of e

volu

tion

by n

atur

al s

elec

tion

can

expl

ain

the

deve

lopm

ent o

f ant

ibio

tic re

sist

ance

in b

acte

ria. (

2.1)

Und

erst

andi

ngs:

• N

atur

al s

elec

tion

can

only

occ

ur if

ther

e is

var

iatio

n am

ong

mem

bers

of t

he

sam

e sp

ecie

s.

• M

utat

ion,

mei

osis

and

sex

ual r

epro

duct

ion

caus

e va

riatio

n be

twee

n in

divi

dual

s in

a s

peci

es.

• A

dapt

atio

ns a

re c

hara

cter

istic

s th

at m

ake

an in

divi

dual

sui

ted

to it

s en

viro

nmen

t and

way

of l

ife.

• Sp

ecie

s te

nd to

pro

duce

mor

e of

fspr

ing

than

the

envi

ronm

ent c

an s

uppo

rt.

• In

divi

dual

s th

at a

re b

ette

r ada

pted

tend

to s

urvi

ve a

nd p

rodu

ce m

ore

offs

prin

g w

hile

the

less

wel

l ada

pted

tend

to d

ie o

r pro

duce

few

er o

ffsp

ring.

• In

divi

dual

s th

at re

prod

uce

pass

on

char

acte

ristic

s to

thei

r off

sprin

g.

• N

atur

al s

elec

tion

incr

ease

s th

e fr

eque

ncy

of c

hara

cter

istic

s th

at m

ake

indi

vidu

als

bett

er a

dapt

ed a

nd d

ecre

ases

the

freq

uenc

y of

oth

er

char

acte

ristic

s le

adin

g to

cha

nges

with

in th

e sp

ecie

s.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

hang

es in

bea

ks o

f fin

ches

on

Dap

hne

Maj

or.

• A

pplic

atio

n: E

volu

tion

of a

ntib

iotic

resi

stan

ce in

bac

teria

.

Gui

danc

e:

• St

uden

ts s

houl

d be

cle

ar th

at c

hara

cter

istic

s ac

quire

d du

ring

the

lifet

ime

of

an in

divi

dual

are

not

her

itabl

e. T

he te

rm L

amar

ckis

m is

not

requ

ired.

Theo

ry o

f kno

wle

dge:

• N

atur

al S

elec

tion

is a

theo

ry. H

ow m

uch

evid

ence

is re

quire

d to

sup

port

a

theo

ry a

nd w

hat s

ort o

f cou

nter

evi

denc

e is

requ

ired

to re

fute

it?

Topic 5: Evolution and biodiversity

Biology guide 69

Esse

ntia

l ide

a: S

peci

es a

re n

amed

and

cla

ssifi

ed u

sing

an

inte

rnat

iona

lly a

gree

d sy

stem

.

5.3

Clas

sifi

cati

on o

f bio

dive

rsit

y

Nat

ure

of s

cien

ce:

Coop

erat

ion

and

colla

bora

tion

betw

een

grou

ps o

f sci

entis

ts—

scie

ntis

ts u

se th

e bi

nom

ial s

yste

m to

iden

tify

a sp

ecie

s ra

ther

than

the

man

y di

ffer

ent l

ocal

nam

es. (

4.3)

Und

erst

andi

ngs:

• Th

e bi

nom

ial s

yste

m o

f nam

es fo

r spe

cies

is u

nive

rsal

am

ong

biol

ogis

ts a

nd

has

been

agr

eed

and

deve

lope

d at

a s

erie

s of

con

gres

ses.

• W

hen

spec

ies

are

disc

over

ed th

ey a

re g

iven

sci

entif

ic n

ames

usi

ng th

e bi

nom

ial s

yste

m.

• Ta

xono

mis

ts c

lass

ify s

peci

es u

sing

a h

iera

rchy

of t

axa.

• A

ll or

gani

sms

are

clas

sifie

d in

to th

ree

dom

ains

.

• Th

e pr

inci

pal t

axa

for c

lass

ifyin

g eu

kary

otes

are

kin

gdom

, phy

lum

, cla

ss,

orde

r, fa

mily

, gen

us a

nd s

peci

es.

• In

a n

atur

al c

lass

ifica

tion,

the

genu

s an

d ac

com

pany

ing

high

er ta

xa c

onsi

st o

f al

l the

spe

cies

that

hav

e ev

olve

d fr

om o

ne c

omm

on a

nces

tral

spe

cies

.

• Ta

xono

mis

ts s

omet

imes

recl

assi

fy g

roup

s of

spe

cies

whe

n ne

w e

vide

nce

show

s th

at a

pre

viou

s ta

xon

cont

ains

spe

cies

that

hav

e ev

olve

d fr

om

diff

eren

t anc

estr

al s

peci

es.

• N

atur

al c

lass

ifica

tions

hel

p in

iden

tific

atio

n of

spe

cies

and

allo

w th

e pr

edic

tion

of c

hara

cter

istic

s sh

ared

by

spec

ies

with

in a

gro

up.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

lass

ifica

tion

of o

ne p

lant

and

one

ani

mal

spe

cies

from

dom

ain

to s

peci

es le

vel.

• A

pplic

atio

n: R

ecog

nitio

n fe

atur

es o

f bry

ophy

ta, f

ilici

noph

yta,

con

ifero

phyt

a an

d an

gios

perm

ophy

ta.

Inte

rnat

iona

l-m

inde

dnes

s:

• Th

ere

are

inte

rnat

iona

l cod

es o

f nom

encl

atur

e an

d ag

reem

ents

as

to th

e pr

inci

ples

to b

e fo

llow

ed in

the

clas

sific

atio

n of

livi

ng o

rgan

ism

s.

Theo

ry o

f kno

wle

dge:

• Th

e ad

optio

n of

a s

yste

m o

f bin

omia

l nom

encl

atur

e is

larg

ely

due

to S

wed

ish

bota

nist

and

phy

sici

an C

arol

us L

inna

eus

(170

7–17

78).

Linn

aeus

als

o de

fined

fo

ur g

roup

s of

hum

ans,

and

the

divi

sion

s w

ere

base

d on

bot

h ph

ysic

al a

nd

soci

al tr

aits

. By

21st

-cen

tury

sta

ndar

ds, h

is d

escr

iptio

ns c

an b

e re

gard

ed a

s ra

cist

. How

doe

s th

e so

cial

con

text

of s

cien

tific

wor

k af

fect

the

met

hods

an

d fin

ding

s of

rese

arch

? Is

it n

eces

sary

to c

onsi

der t

he s

ocia

l con

text

whe

n ev

alua

ting

ethi

cal a

spec

ts o

f kno

wle

dge

clai

ms?

Topic 5: Evolution and biodiversity

Biology guide70

5.3

Clas

sifi

cati

on o

f bio

dive

rsit

y

• A

pplic

atio

n: R

ecog

nitio

n fe

atur

es o

f por

ifera

, cni

daria

, pla

tyhe

lmin

tha,

an

nelid

a, m

ollu

sca,

art

hrop

oda

and

chor

data

.

• A

pplic

atio

n: R

ecog

nitio

n of

feat

ures

of b

irds,

mam

mal

s, a

mph

ibia

ns, r

eptil

es

and

fish.

• Sk

ill: C

onst

ruct

ion

of d

icho

tom

ous

keys

for u

se in

iden

tifyi

ng s

peci

men

s.

Gui

danc

e:

• A

rcha

ea, e

ubac

teria

and

euk

aryo

te s

houl

d be

use

d fo

r the

thre

e do

mai

ns.

• M

embe

rs o

f the

se d

omai

ns s

houl

d be

refe

rred

to a

s ar

chae

ans,

bac

teria

and

eu

kary

otes

.

• St

uden

ts s

houl

d kn

ow w

hich

pla

nt p

hyla

hav

e va

scul

ar ti

ssue

, but

oth

er

inte

rnal

det

ails

are

not

requ

ired.

• Re

cogn

ition

feat

ures

exp

ecte

d fo

r the

sel

ecte

d an

imal

phy

la a

re th

ose

that

are

mos

t use

ful i

n di

stin

guis

hing

the

grou

ps fr

om e

ach

othe

r and

full

desc

riptio

ns o

f the

cha

ract

eris

tics

of e

ach

phyl

um a

re n

ot n

eede

d.

• Vi

ruse

s ar

e no

t cla

ssifi

ed a

s liv

ing

orga

nism

s.

Topic 5: Evolution and biodiversity

Biology guide 71

Esse

ntia

l ide

a: T

he a

nces

try

of g

roup

s of

spe

cies

can

be

dedu

ced

by c

ompa

ring

thei

r bas

e or

am

ino

acid

seq

uenc

es.

5.4

Clad

isti

cs

Nat

ure

of s

cien

ce:

Fals

ifica

tion

of th

eorie

s w

ith o

ne th

eory

bei

ng s

uper

sede

d by

ano

ther

—pl

ant f

amili

es h

ave

been

recl

assi

fied

as a

resu

lt of

evi

denc

e fr

om c

ladi

stic

s. (1

.9)

Und

erst

andi

ngs:

• A

cla

de is

a g

roup

of o

rgan

ism

s th

at h

ave

evol

ved

from

a c

omm

on a

nces

tor.

• Ev

iden

ce fo

r whi

ch s

peci

es a

re p

art o

f a c

lade

can

be

obta

ined

from

the

base

se

quen

ces

of a

gen

e or

the

corr

espo

ndin

g am

ino

acid

seq

uenc

e of

a p

rote

in.

• Se

quen

ce d

iffer

ence

s ac

cum

ulat

e gr

adua

lly s

o th

ere

is a

pos

itive

cor

rela

tion

betw

een

the

num

ber o

f diff

eren

ces

betw

een

two

spec

ies

and

the

time

sinc

e th

ey d

iver

ged

from

a c

omm

on a

nces

tor.

• Tr

aits

can

be

anal

ogou

s or

hom

olog

ous.

• Cl

adog

ram

s ar

e tr

ee d

iagr

ams

that

sho

w th

e m

ost p

roba

ble

sequ

ence

of

dive

rgen

ce in

cla

des.

• Ev

iden

ce fr

om c

ladi

stic

s ha

s sh

own

that

cla

ssifi

catio

ns o

f som

e gr

oups

bas

ed

on s

truc

ture

did

not

cor

resp

ond

with

the

evol

utio

nary

orig

ins

of a

gro

up o

r sp

ecie

s.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

lado

gram

s in

clud

ing

hum

ans

and

othe

r prim

ates

.

• A

pplic

atio

n: R

ecla

ssifi

catio

n of

the

figw

ort f

amily

usi

ng e

vide

nce

from

cl

adis

tics.

• Sk

ill: A

naly

sis

of c

lado

gram

s to

ded

uce

evol

utio

nary

rela

tions

hips

.

Theo

ry o

f kno

wle

dge:

• A

maj

or s

tep

forw

ard

in th

e st

udy

of b

acte

ria w

as th

e re

cogn

ition

in 1

977

by

Carl

Woe

se th

at A

rcha

ea h

ave

a se

para

te li

ne o

f evo

lutio

nary

des

cent

from

ba

cter

ia. F

amou

s sc

ient

ists

, inc

ludi

ng L

uria

and

May

r, ob

ject

ed to

his

div

isio

n of

the

prok

aryo

tes.

To

wha

t ext

ent i

s co

nser

vatis

m in

sci

ence

des

irabl

e?

Biology guide72

Core Topi

c 6:

Hum

an p

hysi

olog

y 20

hou

rs

Esse

ntia

l ide

a: T

he s

truc

ture

of t

he w

all o

f the

sm

all i

ntes

tine

allo

ws

it to

mov

e, d

iges

t and

abs

orb

food

.

6.1

Dig

esti

on a

nd a

bsor

ptio

n

Nat

ure

of s

cien

ce:

Use

mod

els

as re

pres

enta

tions

of t

he re

al w

orld

—di

alys

is tu

bing

can

be

used

to m

odel

abs

orpt

ion

in th

e in

test

ine.

(1.1

0)

Und

erst

andi

ngs:

• Th

e co

ntra

ctio

n of

circ

ular

and

long

itudi

nal m

uscl

e of

the

smal

l int

estin

e m

ixes

the

food

with

enz

ymes

and

mov

es it

alo

ng th

e gu

t.

• Th

e pa

ncre

as s

ecre

tes

enzy

mes

into

the

lum

en o

f the

sm

all i

ntes

tine.

• En

zym

es d

iges

t mos

t mac

rom

olec

ules

in fo

od in

to m

onom

ers

in th

e sm

all

inte

stin

e.

• Vi

lli in

crea

se th

e su

rfac

e ar

ea o

f epi

thel

ium

ove

r whi

ch a

bsor

ptio

n is

car

ried

out.

• Vi

lli a

bsor

b m

onom

ers

form

ed b

y di

gest

ion

as w

ell a

s m

iner

al io

ns a

nd

vita

min

s.

• D

iffer

ent m

etho

ds o

f mem

bran

e tr

ansp

ort a

re re

quire

d to

abs

orb

diff

eren

t nu

trie

nts.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: P

roce

sses

occ

urrin

g in

the

smal

l int

estin

e th

at re

sult

in th

e di

gest

ion

of s

tarc

h an

d tr

ansp

ort o

f the

pro

duct

s of

dig

estio

n to

the

liver

.

• A

pplic

atio

n: U

se o

f dia

lysi

s tu

bing

to m

odel

abs

orpt

ion

of d

iges

ted

food

in

the

inte

stin

e.

Uti

lizat

ion:

• So

me

hydr

olyt

ic e

nzym

es h

ave

econ

omic

impo

rtan

ce, f

or e

xam

ple

amyl

ase

in p

rodu

ctio

n of

sug

ars

from

sta

rch

and

in th

e br

ewin

g of

bee

r.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

2.1

Mol

ecul

es to

met

abol

ism

Topi

c 2.

5 En

zym

es

Topic 6: Human physiology

Biology guide 73

6.1

Dig

esti

on a

nd a

bsor

ptio

n

• Sk

ill: P

rodu

ctio

n of

an

anno

tate

d di

agra

m o

f the

dig

estiv

e sy

stem

.

• Sk

ill: I

dent

ifica

tion

of ti

ssue

laye

rs in

tran

sver

se s

ectio

ns o

f the

sm

all i

ntes

tine

view

ed w

ith a

mic

rosc

ope

or in

a m

icro

grap

h.

Gui

danc

e:

• St

uden

ts s

houl

d kn

ow th

at a

myl

ase,

lipa

se a

nd a

n en

dope

ptid

ase

are

secr

eted

by

the

panc

reas

. The

nam

e tr

ypsi

n an

d th

e m

etho

d us

ed to

act

ivat

e it

are

not r

equi

red.

• St

uden

ts s

houl

d kn

ow th

at s

tarc

h, g

lyco

gen,

lipi

ds a

nd n

ucle

ic a

cids

are

di

gest

ed in

to m

onom

ers

and

that

cel

lulo

se re

mai

ns u

ndig

este

d.

• Ti

ssue

laye

rs s

houl

d in

clud

e lo

ngitu

dina

l and

circ

ular

mus

cles

, muc

osa

and

epith

eliu

m.

Topic 6: Human physiology

Biology guide74

Ess

enti

al id

ea: T

he b

lood

sys

tem

con

tinuo

usly

tran

spor

ts s

ubst

ance

s to

cel

ls a

nd s

imul

tane

ousl

y co

llect

s w

aste

pro

duct

s.

6.2

The

bloo

d sy

stem

Nat

ure

of s

cien

ce:

Theo

ries

are

rega

rded

as

unce

rtai

n—W

illia

m H

arve

y ov

ertu

rned

theo

ries

deve

lope

d by

the

anci

ent G

reek

phi

loso

pher

Gal

en o

n m

ovem

ent o

f blo

od in

the

body

. (1.

9)

Und

erst

andi

ngs:

• A

rter

ies

conv

ey b

lood

at h

igh

pres

sure

from

the

vent

ricle

s to

the

tissu

es o

f th

e bo

dy.

• A

rter

ies

have

mus

cle

cells

and

ela

stic

fibr

es in

thei

r wal

ls.

• Th

e m

uscl

e an

d el

astic

fibr

es a

ssis

t in

mai

ntai

ning

blo

od p

ress

ure

betw

een

pum

p cy

cles

.

• Bl

ood

flow

s th

roug

h tis

sues

in c

apill

arie

s. C

apill

arie

s ha

ve p

erm

eabl

e w

alls

th

at a

llow

exc

hang

e of

mat

eria

ls b

etw

een

cells

in th

e tis

sue

and

the

bloo

d in

th

e ca

pilla

ry.

• Ve

ins

colle

ct b

lood

at l

ow p

ress

ure

from

the

tissu

es o

f the

bod

y an

d re

turn

it

to th

e at

ria o

f the

hea

rt.

• Va

lves

in v

eins

and

the

hear

t ens

ure

circ

ulat

ion

of b

lood

by

prev

entin

g ba

ckflo

w.

• Th

ere

is a

sep

arat

e ci

rcul

atio

n fo

r the

lung

s.

• Th

e he

art b

eat i

s in

itiat

ed b

y a

grou

p of

spe

cial

ized

mus

cle

cells

in th

e rig

ht

atriu

m c

alle

d th

e si

noat

rial n

ode.

• Th

e si

noat

rial n

ode

acts

as

a pa

cem

aker

.

• Th

e si

noat

rial n

ode

send

s ou

t an

elec

tric

al s

igna

l tha

t stim

ulat

es c

ontr

actio

n as

it is

pro

paga

ted

thro

ugh

the

wal

ls o

f the

atr

ia a

nd th

en th

e w

alls

of t

he

vent

ricle

s.

• Th

e he

art r

ate

can

be in

crea

sed

or d

ecre

ased

by

impu

lses

bro

ught

to th

e he

art t

hrou

gh tw

o ne

rves

from

the

med

ulla

of t

he b

rain

.

• Ep

inep

hrin

e in

crea

ses

the

hear

t rat

e to

pre

pare

for v

igor

ous

phys

ical

act

ivity

.

Theo

ry o

f kno

wle

dge:

• O

ur c

urre

nt u

nder

stan

ding

is th

at e

mot

ions

are

the

prod

uct o

f act

ivity

in th

e br

ain

rath

er th

an th

e he

art.

Is k

now

ledg

e ba

sed

on s

cien

ce m

ore

valid

than

kn

owle

dge

base

d on

intu

ition

?

Uti

lizat

ion:

• U

nder

stan

ding

of t

he s

truc

ture

of t

he c

ardi

ovas

cula

r sys

tem

has

allo

wed

the

deve

lopm

ent o

f hea

rt s

urge

ry.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

2.2

Wat

erTo

pic

2.3

Carb

ohyd

rate

s an

d lip

ids

Topi

c 6.

4 G

as e

xcha

nge

Topi

c 6.

6 H

orm

ones

, hom

eost

asis

and

repr

oduc

tion

Aim

s:

• A

im 6

: A h

eart

dis

sect

ion

is su

gges

ted

as a

mea

ns o

f stu

dyin

g he

art s

truc

ture

.

• A

im 8

: The

soc

ial i

mpl

icat

ions

of c

oron

ary

hear

t dis

ease

cou

ld b

e di

scus

sed.

Topic 6: Human physiology

Biology guide 75

6.2

The

bloo

d sy

stem

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: W

illia

m H

arve

y’s

disc

over

y of

the

circ

ulat

ion

of th

e bl

ood

with

th

e he

art a

ctin

g as

the

pum

p.

• A

pplic

atio

n: P

ress

ure

chan

ges

in th

e le

ft a

triu

m, l

eft v

entr

icle

and

aor

ta

durin

g th

e ca

rdia

c cy

cle.

• A

pplic

atio

n: C

ause

s an

d co

nseq

uenc

es o

f occ

lusi

on o

f the

cor

onar

y ar

terie

s.

• Sk

ill: I

dent

ifica

tion

of b

lood

ves

sels

as

arte

ries,

cap

illar

ies

or v

eins

from

the

stru

ctur

e of

thei

r wal

ls.

• Sk

ill: R

ecog

nitio

n of

the

cham

bers

and

val

ves

of th

e he

art a

nd th

e bl

ood

vess

els

conn

ecte

d to

it in

dis

sect

ed h

eart

s or

in d

iagr

ams

of h

eart

str

uctu

re.

Topic 6: Human physiology

Biology guide76

Esse

ntia

l ide

a: T

he h

uman

bod

y ha

s st

ruct

ures

and

pro

cess

es th

at re

sist

the

cont

inuo

us th

reat

of i

nvas

ion

by p

atho

gens

.

6.3

Def

ence

aga

inst

infe

ctio

us d

isea

se

Nat

ure

of s

cien

ce:

Risk

s as

soci

ated

with

sci

entif

ic re

sear

ch—

Flor

ey a

nd C

hain

’s te

sts

on th

e sa

fety

of p

enic

illin

wou

ld n

ot b

e co

mpl

iant

with

cur

rent

pro

toco

l on

test

ing.

(4.8

)

Und

erst

andi

ngs:

• Th

e sk

in a

nd m

ucou

s m

embr

anes

form

a p

rimar

y de

fenc

e ag

ains

t pat

hoge

ns

that

cau

se in

fect

ious

dis

ease

.

• Cu

ts in

the

skin

are

sea

led

by b

lood

clo

ttin

g.

• Cl

ottin

g fa

ctor

s ar

e re

leas

ed fr

om p

late

lets

.

• Th

e ca

scad

e re

sults

in th

e ra

pid

conv

ersi

on o

f fib

rinog

en to

fibr

in b

y th

rom

bin.

• In

gest

ion

of p

atho

gens

by

phag

ocyt

ic w

hite

blo

od c

ells

giv

es n

on-s

peci

fic

imm

unity

to d

isea

ses.

• Pr

oduc

tion

of a

ntib

odie

s by

lym

phoc

ytes

in re

spon

se to

par

ticul

ar p

atho

gens

gi

ves

spec

ific

imm

unity

.

• A

ntib

iotic

s bl

ock

proc

esse

s th

at o

ccur

in p

roka

ryot

ic c

ells

but

not

in

euka

ryot

ic c

ells

.

• Vi

ruse

s la

ck a

met

abol

ism

and

can

not t

here

fore

be

trea

ted

with

ant

ibio

tics.

So

me

stra

ins

of b

acte

ria h

ave

evol

ved

with

gen

es th

at c

onfe

r res

ista

nce

to

antib

iotic

s an

d so

me

stra

ins

of b

acte

ria h

ave

mul

tiple

resi

stan

ce.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

ause

s an

d co

nseq

uenc

es o

f blo

od c

lot f

orm

atio

n in

cor

onar

y ar

terie

s.

• A

pplic

atio

n: F

lore

y an

d Ch

ain’

s ex

perim

ents

to te

st p

enic

illin

on

bact

eria

l in

fect

ions

in m

ice.

• A

pplic

atio

n: E

ffec

ts o

f HIV

on

the

imm

une

syst

em a

nd m

etho

ds o

f tr

ansm

issi

on.

Inte

rnat

iona

l-m

inde

dnes

s:

• Th

e sp

read

and

con

tain

men

t of d

isea

ses

such

as

bird

flu

requ

ire in

tern

atio

nal

coor

dina

tion

and

com

mun

icat

ion.

Uti

lizat

ion:

• A

n un

ders

tand

ing

of im

mun

ity h

as le

d to

the

deve

lopm

ent o

f vac

cina

tions

.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

5.2

Nat

ural

sel

ectio

nCh

emis

try

Topi

c D

2 A

spiri

n an

d pe

nici

llin

Aim

s:

• A

im 8

: The

soc

ial a

s w

ell a

s th

e ec

onom

ic b

enef

its o

f the

con

trol

of b

acte

rial

dise

ases

aro

und

the

wor

ld s

houl

d be

str

esse

d.

• A

im 9

: Sci

ence

has

lim

ited

mea

ns in

the

fight

aga

inst

pat

hoge

ns, a

s sh

own

by

the

spre

ad o

f new

dis

ease

s an

d an

tibio

tic-r

esis

tant

bac

teria

.

Topic 6: Human physiology

Biology guide 77

6.3

Def

ence

aga

inst

infe

ctio

us d

isea

se

Gui

danc

e:

• D

iagr

ams

of s

kin

are

not r

equi

red.

• Su

bgro

ups

of p

hago

cyte

and

lym

phoc

yte

are

not r

equi

red

but s

tude

nts

shou

ld b

e aw

are

that

som

e ly

mph

ocyt

es a

ct a

s m

emor

y ce

lls a

nd c

an q

uick

ly

repr

oduc

e to

form

a c

lone

of p

lasm

a ce

lls if

a p

atho

gen

carr

ying

a s

peci

fic

antig

en is

re-e

ncou

nter

ed.

• Th

e ef

fect

s of

HIV

on

the

imm

une

syst

em s

houl

d be

lim

ited

to a

redu

ctio

n in

the

num

ber o

f act

ive

lym

phoc

ytes

and

a lo

ss o

f the

abi

lity

to p

rodu

ce

antib

odie

s, le

adin

g to

the

deve

lopm

ent o

f AID

S.

Topic 6: Human physiology

Biology guide78

Esse

ntia

l ide

a: T

he lu

ngs

are

activ

ely

vent

ilate

d to

ens

ure

that

gas

exc

hang

e ca

n oc

cur p

assi

vely

.

6.4

Gas

exc

hang

e

Nat

ure

of s

cien

ce:

Obt

ain

evid

ence

for t

heor

ies—

epid

emio

logi

cal s

tudi

es h

ave

cont

ribut

ed to

our

und

erst

andi

ng o

f the

cau

ses

of lu

ng c

ance

r. (1

.8)

Und

erst

andi

ngs:

• Ve

ntila

tion

mai

ntai

ns c

once

ntra

tion

grad

ient

s of

oxy

gen

and

carb

on d

ioxi

de

betw

een

air i

n al

veol

i and

blo

od fl

owin

g in

adj

acen

t cap

illar

ies.

• Ty

pe I

pneu

moc

ytes

are

ext

rem

ely

thin

alv

eola

r cel

ls th

at a

re a

dapt

ed to

ca

rry

out g

as e

xcha

nge.

• Ty

pe II

pne

umoc

ytes

sec

rete

a s

olut

ion

cont

aini

ng s

urfa

ctan

t tha

t cre

ates

a

moi

st s

urfa

ce in

side

the

alve

oli t

o pr

even

t the

sid

es o

f the

alv

eolu

s ad

herin

g to

eac

h ot

her b

y re

duci

ng s

urfa

ce te

nsio

n.

• A

ir is

car

ried

to th

e lu

ngs

in th

e tr

ache

a an

d br

onch

i and

then

to th

e al

veol

i in

bron

chio

les.

• M

uscl

e co

ntra

ctio

ns c

ause

the

pres

sure

cha

nges

insi

de th

e th

orax

that

forc

e ai

r in

and

out o

f the

lung

s to

ven

tilat

e th

em.

• D

iffer

ent m

uscl

es a

re re

quire

d fo

r ins

pira

tion

and

expi

ratio

n be

caus

e m

uscl

es

only

do

wor

k w

hen

they

con

trac

t.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

ause

s an

d co

nseq

uenc

es o

f lun

g ca

ncer

.

• A

pplic

atio

n: C

ause

s an

d co

nseq

uenc

es o

f em

phys

ema.

• A

pplic

atio

n: E

xter

nal a

nd in

tern

al in

terc

osta

l mus

cles

, and

dia

phra

gm a

nd

abdo

min

al m

uscl

es a

s ex

ampl

es o

f ant

agon

istic

mus

cle

actio

n.

• Sk

ill: M

onito

ring

of v

entil

atio

n in

hum

ans

at re

st a

nd a

fter

mild

and

vig

orou

s ex

erci

se. (

Prac

tical

6)

Uti

lizat

ion:

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

1.4

Mem

bran

e tr

ansp

ort

Topi

c 1.

6 Ce

ll di

visi

onTo

pic

6.2

The

bloo

d sy

stem

Phys

ics

Topi

c 3.

2 M

odel

ling

a ga

s

Aim

s:

• A

im 8

: The

soc

ial c

onse

quen

ces

of lu

ng c

ance

r and

em

phys

ema

coul

d be

di

scus

sed.

Topic 6: Human physiology

Biology guide 79

6.4

Gas

exc

hang

e

Gui

danc

e:

• Ve

ntila

tion

can

eith

er b

e m

onito

red

by s

impl

e ob

serv

atio

n an

d si

mpl

e ap

para

tus

or b

y da

ta lo

ggin

g w

ith a

spi

rom

eter

or c

hest

bel

t and

pre

ssur

e m

eter

. Ven

tilat

ion

rate

and

tida

l vol

ume

shou

ld b

e m

easu

red,

but

the

term

s vi

tal c

apac

ity a

nd re

sidu

al v

olum

e ar

e no

t exp

ecte

d.

• St

uden

ts s

houl

d be

abl

e to

dra

w a

dia

gram

to s

how

the

stru

ctur

e of

an

alve

olus

and

an

adja

cent

cap

illar

y.

Topic 6: Human physiology

Biology guide80

Esse

ntia

l ide

a: N

euro

ns tr

ansm

it th

e m

essa

ge, s

ynap

ses

mod

ulat

e th

e m

essa

ge.

6.5

Neu

rons

and

syn

apse

s

Nat

ure

of s

cien

ce:

Coop

erat

ion

and

colla

bora

tion

betw

een

grou

ps o

f sci

entis

ts—

biol

ogis

ts a

re c

ontr

ibut

ing

to re

sear

ch in

to m

emor

y an

d le

arni

ng. (

4.3)

Und

erst

andi

ngs:

• N

euro

ns tr

ansm

it el

ectr

ical

impu

lses

.

• Th

e m

yelin

atio

n of

ner

ve fi

bres

allo

ws

for s

alta

tory

con

duct

ion.

• N

euro

ns p

ump

sodi

um a

nd p

otas

sium

ions

acr

oss

thei

r mem

bran

es to

ge

nera

te a

rest

ing

pote

ntia

l.

• A

n ac

tion

pote

ntia

l con

sist

s of d

epol

ariz

atio

n an

d re

pola

rizat

ion

of th

e ne

uron

.

• N

erve

impu

lses

are

act

ion

pote

ntia

ls p

ropa

gate

d al

ong

the

axon

s of

neu

rons

.

• Pr

opag

atio

n of

ner

ve im

puls

es is

the

resu

lt of

loca

l cur

rent

s th

at c

ause

eac

h su

cces

sive

par

t of t

he a

xon

to re

ach

the

thre

shol

d po

tent

ial.

• Sy

naps

es a

re ju

nctio

ns b

etw

een

neur

ons

and

betw

een

neur

ons

and

rece

ptor

or

eff

ecto

r cel

ls.

• W

hen

pres

ynap

tic n

euro

ns a

re d

epol

ariz

ed th

ey re

leas

e a

neur

otra

nsm

itter

in

to th

e sy

naps

e.

• A

ner

ve im

puls

e is

onl

y in

itiat

ed if

the

thre

shol

d po

tent

ial i

s re

ache

d.

App

licat

ions

and

ski

lls:

• Ap

plic

atio

n: S

ecre

tion

and

reab

sorp

tion

of a

cety

lcho

line

by n

euro

ns a

t syn

apse

s.

• A

pplic

atio

n: B

lock

ing

of s

ynap

tic tr

ansm

issi

on a

t cho

liner

gic

syna

pses

in

inse

cts

by b

indi

ng o

f neo

nico

tinoi

d pe

stic

ides

to a

cety

lcho

line

rece

ptor

s.

• Sk

ill: A

naly

sis

of o

scill

osco

pe tr

aces

sho

win

g re

stin

g po

tent

ials

and

act

ion

pote

ntia

ls.

Gui

danc

e:

• Th

e de

tails

of s

truc

ture

of d

iffer

ent t

ypes

of n

euro

n ar

e no

t nee

ded.

• O

nly

chem

ical

syn

apse

s ar

e re

quire

d, n

ot e

lect

rical

, and

they

can

sim

ply

be

refe

rred

to a

s sy

naps

es.

Uti

lizat

ion:

• A

n un

ders

tand

ing

of th

e w

orki

ngs

of n

euro

tran

smitt

ers

and

syna

pses

has

le

d to

the

deve

lopm

ent o

f num

erou

s ph

arm

aceu

tical

s fo

r the

trea

tmen

t of

men

tal d

isor

ders

.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

y To

pic

1.4

Mem

bran

e tr

ansp

ort

Chem

istr

y To

pic

C6 E

lect

roch

emis

try,

rech

arge

able

bat

terie

s an

d fu

el c

ells

Psyc

holo

gyCo

re: B

iolo

gica

l lev

el o

f ana

lysi

s

Aim

s:

• A

im 8

: The

soc

ial e

ffec

ts o

f the

abu

se o

f psy

choa

ctiv

e dr

ugs

coul

d be

co

nsid

ered

, as

coul

d th

e us

e of

the

neur

otox

in B

otox

for c

osm

etic

trea

tmen

ts.

Topic 6: Human physiology

Biology guide 81

Esse

ntia

l ide

a: H

orm

ones

are

use

d w

hen

sign

als

need

to b

e w

idel

y di

strib

uted

.

6.6

Hor

mon

es, h

omeo

stas

is a

nd re

prod

ucti

on

Nat

ure

of s

cien

ce:

Dev

elop

men

ts in

sci

entif

ic re

sear

ch fo

llow

impr

ovem

ents

in a

ppar

atus

—W

illia

m H

arve

y w

as h

ampe

red

in h

is o

bser

vatio

nal r

esea

rch

into

repr

oduc

tion

by la

ck o

f eq

uipm

ent.

The

mic

rosc

ope

was

inve

nted

17

year

s af

ter h

is d

eath

. (1.

8)

Und

erst

andi

ngs:

• In

sulin

and

glu

cago

n ar

e se

cret

ed b

y β

and

α ce

lls o

f the

pan

crea

s re

spec

tivel

y to

con

trol

blo

od g

luco

se c

once

ntra

tion.

• Th

yrox

in is

sec

rete

d by

the

thyr

oid

glan

d to

regu

late

the

met

abol

ic ra

te a

nd

help

con

trol

bod

y te

mpe

ratu

re.

• Le

ptin

is s

ecre

ted

by c

ells

in a

dipo

se ti

ssue

and

act

s on

the

hypo

thal

amus

of

the

brai

n to

inhi

bit a

ppet

ite.

• M

elat

onin

is s

ecre

ted

by th

e pi

neal

gla

nd to

con

trol

circ

adia

n rh

ythm

s.

• A

gen

e on

the

Y ch

rom

osom

e ca

uses

em

bryo

nic

gona

ds to

dev

elop

as

test

es

and

secr

ete

test

oste

rone

.

• Te

stos

tero

ne c

ause

s pr

e-na

tal d

evel

opm

ent o

f mal

e ge

nita

lia a

nd b

oth

sper

m

prod

uctio

n an

d de

velo

pmen

t of m

ale

seco

ndar

y se

xual

cha

ract

eris

tics

durin

g pu

bert

y.

• Es

trog

en a

nd p

roge

ster

one

caus

e pr

e-na

tal d

evel

opm

ent o

f fem

ale

repr

oduc

tive

orga

ns a

nd fe

mal

e se

cond

ary

sexu

al c

hara

cter

istic

s du

ring

pube

rty.

• Th

e m

enst

rual

cyc

le is

con

trol

led

by n

egat

ive

and

posi

tive

feed

back

m

echa

nism

s in

volv

ing

ovar

ian

and

pitu

itary

hor

mon

es.

App

licat

ions

and

ski

lls:

• A

pplic

atio

n: C

ause

s an

d tr

eatm

ent o

f Typ

e I a

nd T

ype

II di

abet

es.

• A

pplic

atio

n: T

estin

g of

lept

in o

n pa

tient

s w

ith c

linic

al o

besi

ty a

nd re

ason

s fo

r th

e fa

ilure

to c

ontr

ol th

e di

seas

e.

Uti

lizat

ion:

• H

orm

ones

are

use

d in

a v

arie

ty o

f the

rapi

es s

uch

as re

plac

emen

t the

rapi

es.

Sylla

bus

and

cros

s-cu

rric

ular

link

s:Bi

olog

yTo

pic

3.2

Chro

mos

omes

Topi

c 3.

3 M

eios

isTo

pic

10.1

Mei

osis

Psyc

holo

gy

Core

: Bio

logi

cal l

evel

of a

naly

sis

Aim

s:

• A

im 8

: Sci

entis

ts a

re a

war

e th

at th

e dr

ugs

wom

en ta

ke in

fert

ility

trea

tmen

t po

se p

oten

tial r

isks

to h

ealth

. Sho

uld

scie

ntifi

c kn

owle

dge

over

ride

com

pass

iona

te c

onsi

dera

tions

in tr

eatin

g in

fert

ile c

oupl

es?

Topic 6: Human physiology

Biology guide82

6.6

Hor

mon

es, h

omeo

stas

is a

nd re

prod

ucti

on

• A

pplic

atio

n: C

ause

s of

jet l

ag a

nd u

se o

f mel

aton

in to

alle

viat

e it.

• A

pplic

atio

n: T

he u

se in

IVF

of d

rugs

to s

uspe

nd th

e no

rmal

sec

retio

n of

ho

rmon

es, f

ollo

wed

by

the

use

of a

rtifi

cial

dos

es o

f hor

mon

es to

indu

ce

supe

rovu

latio

n an

d es

tabl

ish

a pr

egna

ncy.

• A

pplic

atio

n: W

illia

m H

arve

y’s

inve

stig

atio

n of

sex

ual r

epro

duct

ion

in d

eer.

• Sk

ill: A

nnot

ate

diag

ram

s of

the

mal

e an

d fe

mal

e re

prod

uctiv

e sy

stem

to s

how

na

mes

of s

truc

ture

s an

d th

eir f

unct

ions

.

Gui

danc

e:

• Th

e ro

les

of F

SH, L

H, e

stro

gen

and

prog

este

rone

in th

e m

enst

rual

cyc

le a

re

expe

cted

.

• W

illia

m H

arve

y fa

iled

to s

olve

the

mys

tery

of s

exua

l rep

rodu

ctio

n be

caus

e ef

fect

ive

mic

rosc

opes

wer

e no

t ava

ilabl

e w

hen

he w

as w

orki

ng, s

o fu

sion

of

gam

etes

and

sub

sequ

ent e

mbr

yo d

evel

opm

ent r

emai

ned

undi

scov

ered

.