WJEC Biology 3 Notes

Pretty much everything you need to know for higher tier Biology 3. The notes are somewhat shortened, so if there are any concerns, don't hesitate to contact me. (:

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  • Created by: Lewis
  • Created on: 25-04-11 18:01
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Transpiration
Transpiration is the process whereby plants expel water. Water is absorbed by the roots
and travels in vessels up the stem called xylem tubes to the leaves. There are pores on
the leaves called stomata, surrounded by guard cells. When the plant has lots of water,
the pressure of the turgidity forces the guard cells open, and water is lost through the
stomata. When the plant has little water and is flaccid, the guard cells stay closed, and
transpiration comes to a stop. Factors affecting transpiration are the light level, wind,
humidity, and temperature.
Nutrients Needed By Plants
Nitrates Potassium Phosphate
What do they do? Used to build proteins A necessity for A necessity for
and essential for photosynthesis and photosynthesis and
growth. respiration. respiration.
What happens when There will be yellow There will be poor There will be poor
there is a deficiency? leaves and poor flower and fruit root growth and
growth. growth and discoloured leaves.
discoloured leaves.
Explanation All amino acids contain Potassium must be Phosphate a key
nitrogen. Amino acids present for component of DNA
are the building blocks photosynthesis and molecules and all
of proteins. respiration enzymes to membranes.
function.
The Heart
The heart has four chambers; they are the left ventricle, left atrium, right
ventricle and the right atrium. The heart has four main blood vessels; they
are the vena cava, the pulmonary artery, the aorta and the pulmonary vein.
The heart has four valves, they are; the mitrial valve (also known as the
bicuspid valve), tricuspid valve, aortic valve and the pulmonary valve.
Coronary arteries provide the heart with a blood supply.
The blood travels through the vena cave into the right atrium.
It then enters the right ventricle and exits through the
pulmonary artery where it travels to the lungs. At the lungs,
the haemoglobin picks up oxygen and become
oxyhaemoglobin. The blood then travels from the lungs
through the pulmonary vein into the left atrium. The blood
then travels into the right ventricle and out through the
aorta. The blood then travel to the body and back into the
left atrium through the vena cava.

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Blood Vessels
Arteries: When blood flows out of the heart it enters the arteries. Blood in
the arteries is at a high pressure. Because of this, arteries need strong walls
to withstand this pressure. They have elastic tissue in their walls which
stretch and recoil with the force.
Veins: In the veins, the blood is under much lower pressure. The blood
slows much more slowly, so there is no need for veins to have such thick,
strong elastic walls.…read more

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Removal of urea: Proteins can't be stored by the body, so excess proteins (amino acids) are broken
down in the liver into fats and carbohydrates. The waste product of the breaking down process is
urea. Urea is toxic to the body so it must be expelled somehow. Urea is passed into the blood and is
filtered out by the kidneys; it then enters the bladder as urine and is excreted.…read more

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In a dialysis machine, the person's blood flows alongside a
selectively permeable barrier, surrounded by dialysis fluid. The dialysis fluid has the same
concentration of dissolved ions and glucose as normal blood, therefore, only waste substances
diffuse across the barrier.
Pros and cons of dialysis and kidney transplants:
Dialysis, Pros: Allows you to live a reasonable life and can be used long term.
Cons: Takes up a lot of time and can be draining.…read more

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Size: Some fungi can actually be seen with the naked eye, others are slightly bigger than bacteria
cells.
Examples: Penicillium and yeast.
Shape: Variable.
Reproduction: Yeast reproduces by budding.
White Blood Cells
If we have a cut on our body, then this is an easy route for any
pathogens to enter, this is why our blood clots very quickly to
seal a wound. The two proteins involved in clotting are platelets
and fibrins.
Some white blood cells ingest bacteria.…read more

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annelies paris

It's not working, for me it open up a random document for of links from this website where everytime I press something it redirects to this site and doesn't actually allow me to view anything :/ (if that make sense?)

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