Complete B3 notes all in one.

all my Biology notes. Good luck if you have an exam.

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  • Created on: 20-05-10 16:39
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Exchange of materials.
There are four main points you need to include in a diffusion/ cell adaptation question...
1. Large surface area either through villi or bioconcave disc shape, a large surface area means more
space for diffusion.
2. Rich blood supply this makes sure that a steep concerntration gradient is maintained at all times, by
taking away the diffused subtances. E.g in the nephrone in the Kidney.
3. Moist surfaces this provides an optimum diffusion surface for subtances.
4. There is always a short diffusion distance to make sure that diffusion is quick thus effecient.
The Heart.
The cardiovascular system contains 3 elements, the heart, blood and blood vessels. Without them you
would not live.
The circulatory system is made up of a 'double circulatory pump' which means there is 2 systems which
work together to carry blood around your body.
1. Carries deoxgenated blood from your heart, to the lungs, where it is oxygenated and back again. This
is called the Pulmonary system.
2. The other system carries blood from your heart, to the body supplying oxygen to the nessecery parts,
and back again. This is called the systemic system (remember goes to your system a.k.a the body) but
NOT to the lungs.
The Blood Vessels.
There are 3 main vessels...
1. The arteries. These always carry blood away from the heart (artery away) The work at a high
pressure and have a pulse. They have the thickest walls, to cope with the pressure, and they are also
very elastic.
2. Veins always carry blood to the heart, and work at a lower pressure, so have valves to prevent back
flow of the blood. They have thinner walls and don't pulsate.
3. Capillaries are the smallest vessel, and have very thin walls to make a short diffusion distant for
substances. Your body has a huge network of these vessels.
The Heart.

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The heart uses cardiac muscle, which is very thick and
strong to push the blood around the body.
The Blood.
There are 4 components of your blood...
1. Red blood cells these carry oxygen around your body.
2. White blood cells fight against diseases using antigens, toxins and antibodies.
3. Platelets help clot the blood at wounds, to stop bleeding.
4. Plasma carries waste subtances and hormones etc.…read more

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When photosynsasis is faster, so is transpiration, because the stomata has to open and close more
often.The fastest conditions is warm, sunny, windy, dry conditions for transpiration.
Plants in warm and dry conditions have adapted so that they only open the stomata slightly during the
day, but alot at night, to prevent too much transpiration.
Typical exam question...…read more

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Cheese
Cheese is formed in a similar way, a different starter culture is added to warm milk, and the bacteria
again starts to break down the lactose to form lactic acid, but this time alot more lactic acid is produced.
This means that the curds are alot more solid than in yoghurt. Enzymes are then added to increase
seperation of the curds and whey. When they are completly seperate the curds and whey are serperated
and the curds is what forms the cheese.…read more

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It goes into the Bowman's capsule, where the soluble molecules, water, urea, ions and glucose are
pushed into the capsule, under high pressure, and the other molecules, which are too big, remain in the
blood, such as protein and blood cells. This process is called ultafiltration.
3. The waste products travel down a capillary network along side the blood. Here usefull subtances are
reabsorbed back into the blood. All of the glucose is reabsorbed, because it is needed by the body.…read more

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Overall, the dialysis machine makes sure that the blood is filtered, so that it keeps the usefull
things, and gets rid of the toxic substances.
Many patients have to have dialysis 3 times a week, and it can take as long as 8 hours to complete.
Biogas generators.
People in rural areas (such as farmers in India) have found new ways to create gas which they can use in
cooking, and also use their waste to create the gas.…read more

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