This file contains everything and more there is to know about water for the AQA Biology at A-Level written by an A* level student. The information is written with good knowledge and in depth, providing the enhancement of deeper understanding
Importance water metabolite substance needed for metabolic reaction
:
of : a
metabolite metabolic reactions
·
in many
e
g
. .
condensation/hydrolisis reactions
good solvent
↳ most metabolic reactions take in
place solution
e
. .
g
cytoplasm
· helps with temperature control
↳ heat evaporation
has a
high lantent of
· specific heat capacity
Molecular make-up of water
- negative region
·
16
properties due to molecular structure O water bonded
&
H
water 8 + "st
is a simple molecule
by hydrogen
po sitive region s ↑
1
H
0
.
polar molecule wat er
1-1
bonds
than
oxygen is more
electronegative hydrogen, so shared electrons are attracted more
by
the
oxygen atom, which makes water a
dipole
water molecules are hold
together by intermolecular forces (hydrogen bonds)
↳ molecules
for m and break constantly due to the movement of the
lots of hydrogen bonds are
relatively strong
·
the molecules called cohesion
forming of
hydrogen bonds and
holding the together is
Properties :
Water is liquid :
it requires to
although is simple molecule is liquid hydrogen it lot break them
it > of
a a due to bonds as a
energy
↳
· viscosity,
has low so it flows easy a
single hydrogen bond is weak, but a lot of them
together are
strong
important that it is a liquid so that it can be a solvent ,
or more around materials ,
e
.
.
g
Xylem, blood
Density :
water is denser in its liquid state I due to
hydrogen bonds
it cools under 40c the water molecules lose kinetic less
as
energy so
they move
because get lattices hold (ice) not break to
they move less
they arranged into
together by hydrogen bonds ->
hydrogen bonds do due
movement
the I
molecules are now further apart gigant rigid but
open structure with every exygen at the centre of a tetrahedral arrangement
8G
--
of
hydrogen atoms: ·
=
·
otherwise not float that it would sink the level
good property as ice would so
rising sea
a c ts as an insulating layer for habitat below it an d ensures survival of some aquatic environment
solvent :
solvent for polar molecules
attracted positive of
negative regions by regions solute
positive regions attracted by negative regions of solute
↳ molecules around these dissolved
water cluster
charged par ts -> solute is
&e
.
↳
solution has been formed
&- &B -
-
e
au 8
T
-
- I &
&
sollte
S
·
needed as most reactions happen in
solution, lots of reactions the
cytoplasm
g
. happen in
e
.
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