AS OCR Unit 1 Biology

Everything you need to know for Unit 1 AS OCR Biology, based on the content checklist on the exam cafe cd

Working on a Unit 2 one :)- if you need unit 2 revision I have some Biological Molecules flashcards :DD

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Emi
l
y Summer
s
AS OCR Biology Revision Pack
UNIT f211 Cells, exchange, transport
Module 1 Cells
Cell Structure
1. Stat
e t
he r
esolut
ion
and
magnif
icat
ion
that
can
be
achi
eved
by
a l
i
g ht
mi
croscope,
a
tr
ansmi
ssi
on
elect
ron
mic
roscope
and
a scanni
ng el
ectr
on
micr
oscope.
Light Microscope TEM SEM
Maximum 0.2
mi cr
o metr
es 0.
000 1
micr
omet
res 0.
005
micr
omet
res
Resolution
Maximum X
1500 Over
x
1,000,
000 Under
x
1,
000,
000
Magnification
2. Expl
ain
the
dif
fer
ence
bet
w een
magni
fi
cat
ion
and
resol
uti
on
Magnification
H ow
much
bigger
t
he
image
is
than
the
speci
men.
Magni
fi
cat
ion
= Lengt
h of
I
mage
/
Lengt
h of
speci
men
Resolution
H ow wel
l
a mi
croscope
dist
ingui
shes
bet
w een
two
poi
nts
that
ar
e cl
ose
t
ogether.
3. Expl
ain
the
need
for
st
aini
ng
sampl
es
for
use
in
li
ght
and
elect
ron
micr
oscopy
I
n Li
ght micr
oscopes and
TE M's
the
beam of
l
ight
s/el
ectr
ons pass
thr
ough t
he obj
ect,
and
t
here i
s an
image produced
as some part
s of
t
he speci
me n
absorb more
li
ght
/el
ectr
ons
t
han other
s, but
someti
me s
the
specimen i
s t
ransparent
so
it
wi
ll
l
ook whi
te
because
l
i
g ht
/el
ectrons
pass t
hrough
so t
he
object
i
s st
ained
Light Microscope Electron Microscope
Dye usual
ly
me t
h yl
ene bl
ue/eo si
n Speci
me n
dippe d
in
me tal
l
i
ke l
ea d,
the
metal
i
ons scat
ter
e l
ectr
ons t
o co nt
rast
.
4. Cal
cul
ate
the
li
near
magni
fi
cat
ion
of
an
image
Magnification = Length of Image / Length of specimen
1

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Emi
l
y Summer
s
5. Out
li
ne
the
funct
ions
of
the
str
uct
ures.
Picture Description Function
La r
ge and contai
ns N ucl
eus contai
ns t
he
chromati
n. Encl
ose d
by a cel
l'
s genet
ic
ma t
erial
.
nu cl
ear
en vel
ope C hromati
n
contai
ns DNA
doubl
e me mbrane. and prot
eins
w hi
ch
Nuclear
pores go
through r
eg ul
ate
cell
act
ivi
ti
es.…read more

Page 3

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Emi
l
y Summer
s
Enzyme s br
e ak
dow n
Sp her
ical
sacs cel
ls.
E.g.
wh i
te
blood
surr
ound ed
by a si
ngle cel
l
lyosome s
break
me mb r
ane, wi
th no
clear dow n
invadi
n g
i
nter
nal
str
ucture.
Con t
ains mi croorganisms and
e nzymes. lyosome
in
the sper
m' s
head br
ea ks
dow n
the
ma t
eri
al
su r
rounding t
he
egg.…read more

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Emi
l
y Summer
s
T hi
ck
layer
,
in
plants.
Gives
the
cell
st
rengt
h
Made of
cel
lul
ose i
n and r
igi
dit
y
eukar
yoti
c cel
ls
and
mur
ein
in
prokar
yo t
ic
cel
ls.
I
t
separates
the cel
l
Thi
n,
fl
exibl
e l
a yer
around cont
ents
from exter
nal
al
l
eukaryoti
c cel
ls.…read more

Page 5

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Emi
l
y Summer
s
Rigi
d t
ail
t
h at
r
otates.
"The Propel
s t
he cel
l
mo t
or
is
e mbed ded i
n t
h e
cel
l
me mb r
an e and
is
+
dri
ven by a
H gr
adient
across t
he me mb rane.
Clockwise r
otati
on
dri
ves
the cel
l
for
w ards,
w hi
le
ant
icl
ockw i
se rotat
ion
cause s
a chaoti
c spin.…read more

Page 6

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Page 7

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Emi
l
y Summer
s
12.Expl
ain
the
ter
m cell signalling.
Cel
l
Signal
li
ng
H ow cel
ls
communi
cat
e wi
th
each
other
,
One cel
l
rel
eases a
me ssenger
mo l
ecul
e
(e.
g.
a hor
mo ne)
The
mo l
e cul
e t
ravel
s t
o anot
her
cell
(
E .
g.…read more

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Emi
l
y Summer
s
Expl
ain
the
meani
ng
of
the
ter
m homologous pair of chromosomes
Huma ns
have
46
chromosome s
in
tot
al
23 pairs.
One chr
omo some i
n each
pair
comes
f
rom t
he
mother,
and
then
the
other
come s
fr
o m t
h e
fat
her.
Same si
ze,
same
genes
al
though
they
can have
dif
fer
ent
versi
ons of
the genes
(al
lel
es)
.…read more

Comments

isha8362

That was very useful...thanks :) 

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