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Define Osmosis
movement of water molecules across partially permeable membrane from region of high water concentration to region of low water concentration
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Diffusion is
Movement of particles from areas of high concentration to areas of low concentration
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3 Adaptations of exchange surfaces
1) Thin so only short distance to diffuse 2) Large surface area so lots can diffuse at once 3) In animals have lots of blood vessels to get substances into/out of blood quickly.
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Exchange surface on leaf
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Where does CO2 diffuse into?
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Where do water and Oxygen diffuse out of?
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Size of stomata controlled by
Guard cells
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These close when...
water being lost faster than being replaced by roots
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Shape of leaf does what
Because its flat, this increases surface area
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Water loss with diffusion happens quickest in
Hot dry windy conditions
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Top part of body called
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Lower part of body called
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Thorax + Abdomen separated by
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Air breathed in goes into
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After trachea goes into
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And then
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At end of bronchioles there are
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Breathing in (3 steps)
1) Intercostal muscles + diaphragm CONTRACT 2) Thorax volume INCREASES 3) DECREASING pressure, drawing air IN
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Breathing out (3 steps)
1) Intercostal muscles + diaphragm relax 2) Thorax volume DECREASES 3) INCREASING pressure, forcing air OUT
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Iron lung How did it work?
1) Air pumped out of case. 2) Pressure dropped 3) Lungs expanded drawing air into lungs| THEN | 1) Air pumped into case 2) Pressure increased 3) Air forced out of lungs
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Modern ventilators How do they work?
Pump air into lungs, expanding ribcage. Stop pumping ribcage relaxes and pushes air back out of lungs.
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1 benefit 1 drawback of modern ventilator
Doesn't interfere with blood flow but can cause damage such as burst alveoli.
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How are alveoli specialised to maximise diffusion? (4)
1) Large surface area of about 75m^2 2) Moist lining for dissolving gases 3) Thin walls 4) Good blood supply
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Villi specialised in what ways? (4)
1) Millions of them are present 2) Increase surface area massively so ingested food absorbed quickly into blood 3) Single layered 4) Good blood supply
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Way root hair cells are specialised for absorbing water and minerals
Long and thin so have large surface area for absorbing water and minerals
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How do root hair cells take in minerals?
Using active transport
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Concentration of minerals inside root hair cell usually higher than in soil around it
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Use of active transport in human body
Taking nutrients out of blood into gut (as blood may have higher concentration of nutrients)
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Active transport requires ______ from ______ in order to work
Energy from respiration
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Phloem tubes transport....
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3 Features of Phloem tubes
1) Made of columns of LIVING cells with small holes in ends. 2) Transport food (usually dissolved sugars) to growing regions and storage organs 3) Transport can go in BOTH directions
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2 Features of Xylem
1) Made of DEAD cells joined end to end with o walls between them and hole down middle. 2) They carry water + minerals to stem and leaves in transpiration stream.
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Transpiration is.....
loss of water from plant
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Transpiration is caused by....
evaporation and diffusion of water from inside the leaves
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This evaporation and diffusion causes slight shortage of water in leaf... so...
more water is drawn up from rest of plant through xylem to replace it
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This in turn means...
water is drawn up from roots and so there is a constant transpiration stream of water through the plant
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Humans have a ______ circulatory system
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First circuit....
pumps deoxygenated blood to the lungs to take in oxygen and then returns the blood to the heart.
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The second circuit....
Pumps oxygenated blood around all other organs of body. This blood gives up its oxygen at body's cells and deoxygenated blood returns to the heart to be pumped out to lungs again.
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Heart has ____ o make sure blood goes in right direction
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Blood flows INTo the two atria from the ________ and the ________.
Vena cava and the pulmonary vein
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Atria contract pushing....
blood into the ventricles
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Ventricles contract, forcing blood into
pulmonary artery and the aorta and out of the heart
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Blood then flows to _____ through ________
organs through arteries
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and returns through....
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Atria fill and whole cycle restarts
Yay circulation!
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Arteries carry
blood away from heart
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involved in exchange of materials at tissues
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carry blood to the heart
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ARTERIES carry blood...
under pressure
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And therefore require artery walls to be
strong and elastic
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Walls of arteries are
thick compared to hole down middle (lumen)
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These walls contain
thick layers of muscle to make them strong and elastic fibres to allow them to stretch and spring back
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Arteries branch into
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Capillaries carry
blood very close to every cell so that substances can diffuse
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Capillaries have
permeable walls so substances can diffuse
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Capillaries supply _____ and take away _____
take away CO2 and supply food/O2
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Capillary walls are usually only
1 cell thick so increases the rate of diffusion by decreasing distance over which it occurs
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Veins take
blood back to heart
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Capillaries join up to form
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Blood in veins is at
lower pressure so walls don't need to be as thick
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Veins have bigger _____ than arteries
lumen, despite lower pressure, in order to help blood flow
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Veins have ______ to help keep blood flow in right direction
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Red blood cells...
carry oxygen
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RBC's have biconcave shape meaning
larger surface area for absorbing oxygen
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RBC's do not have
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In lungs haemoglobin combines with ______ to make ____
oxygen to make oxyhaemoglobin
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In body tissues oxyhemoglobin splits up into ____
haemoglobin and oxygen to release oxygen in the cells
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WBC defend against disease by (3 ways)
1) Ingesting 2) antibodies 3) antitoxins
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WBC's have a
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Platelets help
blood clot
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Platelets are small fragments of
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Platelets have no
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Platelets help blood clot at wounds to (2)
1) stop bleeding 2) keep microorganisms out
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Plasma is
liquid that carries everything in the blood
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Plasma carries (6)
1) RBC, WBC, Platlets 2) Nutrients e.g. amino acids, glucose, etc 3) CO2 from organs to lungs 4) Urea 5) Hormones 6) Antibodies and antitoxins produced by WBC
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Artificial blood is
Eg saline and makes up for lost blood volume so heart can still pump blood around body
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Advantage of artificial hearts
Not rejected by immune system as are made from metals or plastic
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Surgery can lead to bleeding and infection, and artificial won't work as well as natural ones, and could fail. Has to take blood thinners which can cause bleeding
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Sometimes just
valves can be replaced with mechanics valves
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Stents keep arteries open.
1) Placed in with balloon 2) Inflated 3) balloon removed. All of this pushes artery wall out squashing fatty deposit and making more space in centre of artery
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6 things to be controlled by homeostasis
1) body temp 2) water content 3) ion content 4) blood sugar 5) CO2 6) urea
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when too hot (skin reaction)
1) Hairs lie flat 2) sweat produced by glands and evaporates from skin removing heat 3) blood vessels dilate so more blood flows close to surface of skin to be lost by infrared
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when too cold (skin reaction)
1) hairs stand up to trap insulating layer of air 2) no sweat produced 3) blood vessels supplying skin capillaries constrict to close of skins blood supply 4) shiver(muscle contraction rapidly): requires respiration which releases energy to warm body
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CO2 made by removed by
respiration, breathing out
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Urea formed by
breaking down amino acids in liver
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Urea removed by
blood > kidneys >urine
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kidney main 3 roles
1) removal of urea from blood 2) adjustment of ions 3) adjustment of water content
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Stage 1 of Kidneys
Food digested by small intestine. broken down into amino acids and absorbed into blood.
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Stage 2
Amino acids used to make proteins
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Stage 3
Waste amino acids converted to urea
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Stage 4
Urea travels to kidneys in blood plasma
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Stage 5
Kidneys filter into urine
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FILTRATION in kidneys
All blood filters. Small molecules pass through e.g. water glucose urea and ions
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useful things put back. All glucose, some water and ions, water via osmosis, glucose and ions by active transport
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Left over is urine: urea and excess ions and water
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Glucose is not excreted in urine because:
once it enters the kidney glucose is filtered out from blood. Through active transport it is taken back to blood.
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Kidney stones are
High salt and minerals in diet lead to stones precipitating out. Are extremely painful. Have to be excreted from body in urine.
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Renal damage or failure
Kidney can no longer function and filter blood effectively. Plasma not reabsorbed, proteins and cells pass through bowman's capsule.
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Living without kidneys:
Person can survive with only one kidney, but no kidneys = death
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Solutions (2)
Dialysis, Transplant
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Dialysis fluid contains...
low salt and urea meaning excess salt moves out of blood by diffusion along concentration gradient
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level of glucose in dialysis fluid
is equal to level in blood so there is no net movement
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Transplant stages (4)
1) Organ removed from dead/living person 2) Inserted and connected to patient 3) Damaged organs sometimes removed 4) Donor organ not always connected to position of old organ
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Starch and sugar are broken into _______ by digestion
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Glucose enters blood stream causing
blood glucose levels to rise
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some glucose will be used...
in cells for respiration
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Blood sugar needs to be maintained by__________
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So blood sugar concentration is measured and controlled by the
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Pancreas produces ______ which allows...
insulin, allows glucose to move from blood into cells to be stored
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Also stored in ______ as _______
in liver as glycogen
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Too much glucose can _________
damage cells
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Too little....
means cells can't respire
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Blood glucose falls...
Pancreas releases glucagon
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breaks down glycogen and ______
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releases glucose
blood sugar level back to normal
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Type 1 diabetes is...
early onset
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When pancreas stops...
producing enough insulin....
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blood glucose gets too high and causes...
damage to cells
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Type 1 diabetes is...
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Symptoms of Type 1 diabetes
glucose lost in urine, lack of energy, enter coma and die
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Treatment of Type 1 diabetes
avoid foods which high in carbs, exercise after carbs, inject insulin before meals
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Type 2 diabetes is...
not early onset, found in adults
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What is type 2 diabetes
So much insulin produced due to bad diet/lifestyle that cells become resistant to insulin so do not take glucose into themselves. More insulin needed.
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glucose lost in urine, tired, lack of energy, enter coma and die
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lose weight, diet, insulin injections (last resort)
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Water pollution by humans
Sewage and toxic chemicals from industry, and fertilisers
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Land pollution by humans
Toxic chemicals for farming, bury nuclear waste, dump household waste
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Air pollution
smoke and gases released into atmosphere pollute the air e.g. SO2(g) leading to HSO4(aq)
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4 Main Deforestation Problems:
1) More Methane in atmosphere - cattle and rice 2) More CO2 in atmosphere 3) Less CO2 taken in 4) Less biodiversity
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Destroying Peat Bogs adds...
more CO2 to atmosphere
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Bogs are
acidic and waterlogged areas of land
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Plants in bogs
don't fully decay when they die because theres not enough O2 so build up and form peat
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Draining bogs means
They decompose meaning CO2 released
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Fuels can be made by
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Yeast fermentation to make ethanol equation (Breaking down of sugars with anaerobic respiration)
Glucose ----> ethanol + carbon dioxide + energy
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Biogas is usually __% Methane and __CO2
70 , 30
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2 Types of biogas generators:
Batch and continuous
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Batch key points
Makes in small batches, manually loaded
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Continuous key points
Waste continually fed in, steady rate, large scale
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Why is Biofuel carbon neutral
CO2 released was taken in by plants that lived recently
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Methane benefit of biofuel
Taken in and not released into atmosphere rather than flying into atmosphere because its untreated
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Improving efficiency of Food Production: (3)
1) Reducing number of stages in food chain 2) Restricting energy lost 3) Developing new food sources like mycoprotein Quorn fusarium
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Fish stocks can be maintained via (2)
net size set limits depending on whats being fished, and fishing quotas
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Other cards in this set

Card 2


Diffusion is


Movement of particles from areas of high concentration to areas of low concentration

Card 3


3 Adaptations of exchange surfaces


Preview of the front of card 3

Card 4


Exchange surface on leaf


Preview of the front of card 4

Card 5


Where does CO2 diffuse into?


Preview of the front of card 5
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