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Slide 1

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Gas and Solute Exchange
Osmosis is the movement of water
Life processes need gases or other Diffusion is the net movement of
across a partially permeable
dissolved substances before it can take particles from an area of high
membrane from an area of high
place for example respiration needs concentration to an area of low
concentration to an area of low
oxygen. concentration.
concentration .
Diffusion and osmosis both involve Gases and dissolved substances have
moving particles from high to low to pass through a exchange surface.
concentration, sometimes it needs to The exchange surface structures have
move from an area of low to high to allow enough of the necessary
concentration, This would be active substances to pass through for
transport. example guard cells opening stomata.…read more

Slide 2

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Structure of a leaf
Carbon dioxide diffuses into the The walls of the cells form
air spaces in the leaf, it then another exchange surface and The best conditions for
diffuses into the cells. the air spaces increase the transpiration is hot, dry and
Photosynthesis then occurs. The surface area so more carbon windy.
leaf structure is adapted for this. dioxide can get in and out.
The underneath surface of a leaf
The flattened shape of the leaf
is an exchange surface, it is
increases the area of this
covered by stomata which
exchange surface so it is more
allows carbon dioxide to diffuse
Water vapour and oxygen all
The size of the stomata is
diffuse out of the stomata
controlled by guard cells, these
however some water vapour
close and open the stomata to
can be lost on the top of the leaf
allow water in and out.
structure.…read more

Slide 3

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The Breathing System
· Intercostal muscles and diaphragm
· Thorax volume increases.
Bronchioles end at small · This decreases the pressure drawing
The thorax is the top part bags called alveoli. This is air in.
of the body. where gas exchange Breathing in
It is separated from the The bronchi split into
rest of the body by the smaller tubes called
diaphragm. bronchioles. · Intercostal muscles and diaphragm
· Thorax volume decreases.
· This increases the pressure forcing
air out.
The air you breathe goes
The lungs are like big pink Breathing out
through your trachea and
sponges are protected by
into two tubes called
the rib cage.
bronchi.…read more

Slide 4

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Specialised Cells Circulatory System
Alveoli has an enormous The heart is a double pump,
surface area, moist lining, right side pumps Arteries carry blood away
very thin walls and good deoxygenated blood and the from the heart at high
blood supply. left pumps oxygenated pressure.
Veins collect deoxygenated
Villi is a single layer of cells, blood and carry into back to The arteries split of into
good blood supply and large the heart at low pressure, capillaries which take blood
surface area they contain back flow to every cells.
Root hair cell has a large Exceptions: pulmonary
surface area and thin cell artery and vein.
walls…read more

Slide 5

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The Blood
Red blood cells which contain haemoglobin,
White blood cells which produce antibodies combine with oxygen to form
and antitoxins. oxyhaemoglobin. Have a large surface area
and no nucleus.
Plasma contains red and white blood cells,
Platelets are small fragment s of cells are
platelets, carbon dioxide, urea , nutrients and
help blood to clot.
hormones…read more

Slide 6

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Exercise increases heart rate because breathing rate
Glycogen is used during exercise because the muscles
increases. Arteries dilate to supply oxygen to
use glucose rapidly and have to use the glycogen to
muscles. More respiration takes place and energy
provide the extra energy.
Anaerobic respiration occurs in the lack of oxygen
and is the incomplete breakdown of glucose which Oxygen debt is when you stop exercising you have to
produces lactic acid. Does not release as much energy breathe harder for a longer period of time to break
as aerobic respiration. Keeps muscles going a bit down lactic acid.
longer.…read more

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