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LIFE PROCESSES…read more

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Gas & Solute Exchange
Diffusion, Osmosis and Active Transport Structure of Leaves
· life processes need gases or other dissolved carbon dioxide diffuses into the air
substances before they can happen and waste spaces within the leaf then into the cells
substances also need to move out of the cells so that where photosynthesis happens, the leaf'
the organism can get rid off them, these substances s structure is adapted for this
move to where they need to be by diffusion, osmosis · underneath of the leaf is an exchange
and active transport surface, it's covered in little holes called
· diffusion is where particles move from an area of stomata which the carbon dioxide
high concentration to an area of low concentration diffuses in through
· osmosis is the movement of water particles across · water vapour and oxygen also diffuse
a partially permeable membrane from an area of out through the stomata
high water concentration to and area of low · the size of the stomata are controlled
concentration by guard cells, these close the stomata if
· diffusion and osmosis involve stuff moving from an the plant is losing water faster than it is
area where there's a high concentration of it to an being replaced by the roots
area where there's lower concentration of it, · flattened shape of the leaf increases
sometimes substances need to move the other the area of this exchange surface
direction, this is active transport making it more effective
· the exchange surface is where gases and · walls of the cells inside the leaf form
dissolved substances move through, they have to another exchange surface, the air
allow enough of the necessary substances to pass spaces inside the leaf increase the area
through, they are adapted to maximise effectiveness of this surface so there's more chance
for carbon dioxide to get into the cells…read more

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Breathing System
The lungs need oxygen from the air to get into your blood stream so that it can get to your cells
for respiration and carbon dioxide needs to be dispose of. Breathing is how the air gets in and
out of your lungs.
Lungs Are in the Thorax
· thorax: top part of the body
· lungs are separated from
the lower part by the
diaphragm and protected by
the ribcage
· air you breathe in goes
through the trachea
(windpipe) and this splits into
two tubes called bronchi, one
going to each lung
· the bronchus splits into lots
of smaller tubes called
bronchioles
· bronchioles end at small
bags called alveoli where the
gas exchange takes place…read more

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intercostal muscles: muscles between ribs
· sternum: bone in the middle of the chest
Breathing · diaphragm: sheet of muscles below the lungs
· thorax: top part of body
Breathing In (Inhaling) Breathing Out (Exhaling)
· intercostal muscles contract pulling the ribcage · intercostal muscles relax, dropping the
and sternum up and out, expanding the ribcage ribcage and sternum down and in,
· diaphragm contracts, pulling downwards to contracting the ribcage
increase the volume of the chest · diaphragm relaxes, moving back upwards
· thorax volume increases, decreasing the to decrease the volume of the chest
pressure inside the chest so air is sucked into · thorax volume decreases, increasing the
the lungs pressure inside the chest so air is forced out…read more

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Diffusion ­ Cell Membranes
Gas Exchange Happens in the Lungs
· the lungs job is to transfer oxygen to the blood and remove waste carbon dioxide from it
· they contain millions of little air sacs called alveoli where gas exchange takes place
· alveoli are specialised to maximise the diffusion of oxygen and carbon dioxide:
· enormous surface area
· moist lining - dissolving gases
· very thin walls
· copious blood supply
Villi Provide Really Big Surface Area
· inside of the small intestine is covered
in millions of these tiny little villi
· they increase the surface area in a big
way so that digested food is absorbed
much more quickly into the blood
· they have single layer of surface cells
and a very good blood supply to assist
quick absorption…read more

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Comments

Dominique

Missing a few topics.. Still helpful tho.

H.M-

^ Yes, because this is according to the old syllabus. -_- .

H.M-

Very informative. Just the thing I needed.

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