Edexcel Additional Science
Biology Topic 2- Life
Processes
Respiration
The process of breaking down
glucose to release energy, which goes
on in every living cell
Aerobic Respiration- uses oxygen, it's
the most efficient way to release
energy from glucose. Muscles need the
02 to respire and gain energy etc.
Glucose + Oxygen -> Carbon Dioxide +
Water (+ Energy)
Anaerobic Respiration- happens during
quick and intense exercise, when there's
not enough oxygen. It doesn't release as
much energy and produces a build up of
lactic acid which can result in cramps
After anaerobic respiration you have an
oxygen debt, the amount of O2 needed
to 'repay' is called EPOC. Excess
Post-Exercise Oxygen Consumption. Your
breathing rate gets higher after you
stop to get O2 into your system,
additionally your heart rate stays up to
get O2 to your muscles. it converts lactic
acid into CO2 and H20
Glucose -> Lactic Acid (+ Energy)
Cardiac Output= Heart Rate x
Stroke Volume
Waste and Raw Materials
Waste and Raw Materials diffuse in
and out of cells. Diffusion is the
movement of particles from an area
of high concentration to low
concentration
The circulatory system carries
glucose, O2 and C02 around the body
in the blood. Glucose comes from the
digestive system; oxygen from
breathing and C02 is breathed out.
Capillaries supply the glucose and 02
and take away C02
When cells respire, O2 and glucose is
used up so the concentration is low.
The concentration of the substances in
the blood is lower so they diffuse
from the capillary into the blood
When cells respire they produce CO2.
The concentration of CO2 in cells is
higher than in the capillaries so it
diffuses out. The bigger the difference
in concentration the faster the rate of
diffusion.
Photosynthesis
Photosynthesis is the process of making
'food' in plants. The 'food' is glucose. it
happens inside chloroplasts. the chlorophyll
inside absorbs energy from sunlight and
uses it to convert C02 and H20 into O2 and
glucose
Carbon
Dioxide
+
Water
->
Glucose
+
Oxygen
Adapt-
ations of
Leaves
they're broad so
they have a large
surface area exposed
to light
Contain lots of
chloroplasts
and chlorophyll
to absorb light
they're thin- decrease the distance C02
has to diffuse
they've got holes called stomata; they
open and close to let gases like C02 and
02 in and out
Limiting
Factors
Light- Not enough light slows down the rate of
photosynthesis. light provides energy for photosynthesis, if
you increase the intensity the rate of photosynthesis will
also increase to a point. Beyond that it wont make a
difference because another factor will be limiting
C02- the amount available will also affect the rate of
photosynthesis because it's a raw material needed.
increasing the quantity will increase the rate up to a point
but other limiting factors will prevent it from increasing
any further
Temperature- generally if temp is a limiting factor it is
because it's too low the enzymes needed for
photosynthesis dont work and if its too hot the enzymes
will be denatured.
Structure Of Leaves
Epidermis is
thin and
transparent to
allow more light
to reach the
palisade cells
thin cuticle
made of wax
to protect
the leaf but
not block out
light
there's a palisade
layer of cells at the
top of the leaf
containing
chloroplasts to
absorb light
Transport in Plants
OSMOSIS- the movement of water particles
through a semi-permeable membrane from an
area of high concentration to low concentration
Takes in water by osmosis. Their
long hairs stick out into the soil. The
entire branch of a root is covered in
millions of these cells; this gives the
plant a karge surface area for
absorbing water. there's usually a
higher concentration of water in the
soil than in the roots, so water can
enter via osmosis
Minerals are taken in by active
transport. the concentration in the
soil is usually lower than in the root
hair cell so minerals can get in by
diffusion. Active transport uses
energy from respiration to help the
plant pull minerals into the root
against the concentration gradient.
Plants have tube networks to move substances
to and from cells
XYLEM- transports
water and minerals
from the roots to
the rest of the plant.
TRANSPIRATION
transpiration is the loss of water in a plant and
is caused by the evaporation and diffusion of
water in leaves
when water is lost, it creates a slight shortage. so
more water is pulled up through the xylem
vessels to replace it. this is a transpiration stream
which is a side effect of the way leaves are
adapted to photosynthesis. their stomata allows
gases to be exchanged but also allows water to
escape.
PHLOEM- transports
sugars from the leaves
to growing and storage
tissues
ROOT
HAIR
CELLS
Distribution of Organisms
Environ-
mental
Factors
environmental factors could effect the distribution of
organisms
Temperature measure using a thermometer or probe
Soil pH- use indicator liquid or an electronic pH monitor
Light Intensity- use an electronic light sensor
METH
-ODS
POOTERS- jars with a rubber bung. 2 straws stick out of
the bung and into the jar; one is longer than the other. the
shorter one has mesh covering the opening inside the jar to
prevent insects getting sucked into your mouth. the larger
tube is used to put over the insect and using the short one
suck. So it ends up in the jar
PITFALL TRAPS- place a steep sided container into the
ground so that the opening is at ground level. put the lid on
stones so it's raised but insects can still crawl under. leave
over night and see how many insects have fallen in.
SWEEP NETS- a net lined with strong cloth for collecting
insects, spiders etc from long grass. Stand in your first
sample area and sweep the net and turn the insects out into
a container and count them.
POND NETS- used for collecting insects, water snails etc
from ponds and rivers. sweep it along the bottom, turn it out
and count.
QUADRANTS- a square frame that is divided up and encloses
an area. Random areas of the quadrant are chosen and the
organisms counted, this is repeated and the results compared
for all methods repeat in different sample areas and work
out avergaes