Important B3 notes excluding controlling blood sugar, temperature control and humand and the environment notes.

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  • Created by: Toni
  • Created on: 06-04-13 10:49


TURGID: when water passes into the permenant vacuole by osmosis. The vacuole fills all the cell and pushes against the cell wall. This gives the plant stem support and the cell wall prevents the cell from bursting.

FLACCID: when water moves out of the permenant vacuole by osmosis. The vacuole is much smaller and takes up less space.

PLASMOLYSIS: this is when a lot of water leaves the cell, it leads to the cytoplasm peeling away from the cell wall and the vacuole shrinking in size.

OSMOSIS IN ANIMALS: is important as animal cells use water in chemical reactions.

  • however, osmosis can also destroy red blood cells.
  • animal cells do not have a cell wall to stop the swelling, just a flexible cell membrane

HAEMOLYSED: when an animal cells put in a concentrated solution they lose water by osmosis until they become shrunken or haemolysed.

TURGID THEN BURST: when animal cells are put in pure water they take it in by osmosis until they burst.

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  • goes from area of low concentration to high, therefore sometimes going against the concentration gradient.
  • requires energy from respiration.
  • enables cells to absorb ions from very dilute solutions.

*root hair cells are specialised for absorbing water and minerals

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  • large surface area
  • being thin (provides a short diffusion path)
  • efficient blood supply (in animals - maintains the concentration gradient + moves diffusing substances away)
  • ventilated (in animal) -makes gaseous exchange more efficient by maintaining a steep concentration gradient.


1. The surface area of the lung is increased by the cluster of alveoli.

2. The alveoli have a rich blood supply which maintains a concentration gradient in both directions.

3. This means that oxygen constantly moves from air, to the lungs to the blood.

*CO2 is constantly delivered into the luns from the blood

Alveoli - thin walls, moist lining, rich blood supply + large surface area

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  • requires pressure changes in the lungs -> air is forced in an out of alveoli
  • pressure changes are brought about by the diaphragm and intercostal muscles

internal intercostal muscles - contraction leads to exhalation

external intercostal muscles - contraction leads to inhalation

1.internal intercostal muscles contract, pulling the ribs up and out diaphragm flattens

2. volume of thorax increases

3. pressure in thorax decreases

4. air enters the lungs

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  • thin: short distance
  • flat: increased surface area
  • air space: allows CO2 to contact with cells, thus creating a large surface area for diffusion

CO2 CONTROLLED: by the stomata (found on the underside of the leaf)

  • allows CO2 in and oxygen out
  • maintains steep concentration gradient
  • opened an close by guard cells
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  • when exercising our sodium levels decrease as the salt is lost in sweat.
  • sports drinks contain sodium ions which replace the sodium we have lost.
  • thus enabling us to exercise longer without feeling dehydrated.
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PULMONARY CIRCUIT: pumps deoxygenated blood to the lungs

SYSTEMATIC CIRCUIT: pumps oxygenate blood to the rest of the body (head, limbs, body)


Arteries - carries oxygenated blood away from the heart to organs. bigger thicker layers and walls as the pressure is needed to transport blood to vital places.

Veins - carries blood (low in oxygen) to the heart. has thinner walls and valves which prevent back flow.

Capillary - walls are a single cell thick that allows CO2 to pass through into the blood, has tiny vessels that allow oxygen and glucose to diffuse easily out of blood into cells.

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  • blood enters right atrium through the vena cava.
  • de-oxygenated blood travels through right ventricle which pumps blood through the pulmonary circuit through the pulmonary artery to the lungs.
  • oxygenated blood comes from lungs through pulmonary vein and enters left atrium.
  • oxygenated blood pumped by left ventricle through to the systematic circuit.
  • blood is pumped by left ventricle through the aorta to the head and body.
  • blood then flows back to the vena cava.
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  • opens up a narrow or blocked artery

* a tiny balloon is inflated to open up te blood vessel and the stent at the same time. Which enables blood to flow freely.

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blood is a tissue and consists of a fluid called plasma (55%)

plasma contains: glucose, ions, CO2, urea, proteins, hormones, amino acids and other sugars.

*plasma is a transport medium

floating in plasma - white blood cells (1%), red blood cells (35%) and platelets (9%)

red blood cells: transports oxygen from lungs, carried to tissue and cells.

  •  biconcave shape which increases the surface area:volume ratio. which increases rate of diffusion for oxygen to take place.

white blood cells: forms antibodies against microorganisms

  • digests invading bacteria and viruses.

platelets: clots the blood at wounds and are small fragments of cells.

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  • prolongs the patients life


  • need to change battery
  • discomfort from battery and heart
  • risk of infection
  • operation may fail
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  • carries water and mineral ions from soil to plant
  • secondary function of support
  • cells are dead (impermeable cell wall) and thick walls of lignin
  • no cross-walls = smooth transport
  • one way flow - roots to leaves


  • transports sugars and other molecules created by photosynthesis
  • cells are alive (permeable cell wall) and thin walls of cellulose
  • cross-walls are perforated: allows dissolved sugars and other molecules through but does not allow other substances through.
  • two way flow - to all parts of the plant
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acts as a substitute for red blood cells.

> designed to transport just oxygen and CO2 to the body.


  • dissolves 50 times more blood than plasma
  • cheap (made without biological materials - less chance of disease)
  • not soluble in water (must be combined with emulsifier)
  • carries less oxygen, more PFC would have to be used
  • no profit made (not commercially successful)


  • oxygen covalently bonds with product, thus producing more oxygen than blood
  • not always needed to be kept refrigerated
  • only lasts 25 hours in the body
  • does not clot or fight disease
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gets rid of waste products e.g- Urea in urine (poison) & maintains internal water levels

Artery - filters the blood and urine becomes concentrated

Vein - transports clean blood out of kidney

Ureter - waste and fluids go out in urine

homeostasis in kidneys: 

  • filtering the blood
  • re-absorbs all sugars
  • re-absorbs dissolved ions
  • re-absorbs as much water as body needs
  • releases urea, excess salts and excess water as urine

osmoregulation: controls the amount of dissoved substances in blood & tissue fluid (water)

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  • cleans the blood
  • contains some useful substances as blood
  • dialysis restores high urea and mineral ion levels to a more stable, normal levels


  • have to follow a very controlled diet
  • spend regular and long hours connected to machine
  • balance of substances in blood is difficult to control
  • expensive

*dialysis keeps kidney sufferers alive.

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KIDNEY TRANSPLANTS: diseased kidneys replaced with single healthy kidney

prevention of rejection -

  • kidneys taken from same blood group
  • given drugs to suppress immune response to new antigens
  • disadvantages of immunosuppressant drugs: prevents patient from dealing effectively with infectious diseases. also expensive.

* transplants don't lat forever. works for around 9 years then patient returns to dialysis.

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