Biology Unit 3 (AQA)

Exchange of Materials
1. Osmosis
  1. Diffusion takes place when particles are free to move - in cells, a membrane prevents this, so osmosis takes place
  2. Partially Permeable Membrane must be present
  3. When Water moves from an area of HIGH water concentration to an area of LOW water concentration
  4. Depending on concentration of water/ions outside the cell, could cause cells to shrink and shrivel/swell and burst
2. Active Transport
  1. Transport Proteins are used
  2. Takes a useful molecule, rotates and releases it into the cell
  3. Respiration is required (as energy is used by the proteins)
  4. Used in plant root hair cells, and animal gut cells
3. The Sports Drink Dilemma
  1. Sweating causes you to lose ions and water
  2. Osmosis then occurs, taking water out of the cells
  3. Types of Sport Drink
    1. Isotonic - Contains Fluid and Glucose
    2. Hypetonic - Contains many ions and a lot of Glucose
    3. Hypotonic - Contains Fluid - very low carb content
4. The Lungs
  1. Large Surface Area
  2. Short diffusion path (thin walls)
  3. Efficient Blood Supply - maintains steep concentration gradient
  4. Ventilated - maintains steep concentration gradient
5. Ventilating the Lungs
  1. Moving Air IN
    1. Diaphragm contracts and ribs are moved upward and outward
    2. Creates a lower pressure inside the lungs - forcing air in from outside
  2. Moving Air OUT
    1. Diaphragm relaxes and ribs are moved downward and inwards
    2. Creates a higher pressure inside the lungs - forcing air out from inside
6. Artificial Breathing Aids
  1. Iron Lung
    1. Negative Pressure
    2. Large Tank - patient is contained
      1. A vacuum is formed and the patient's lungs expand, leading to there being a low pressure in the lungs - drawing air in form the outside
  2. Positive Pressure
    1. Either Mask or Surgically Installed
      1. Patient is free to move about, air is forced into and pumped out of the lungs by a machine - is needed for a long time must be surgically inserted into the throat and kept in place
7. Exchange in the gut
  1. Villi
    1. Large Surface Area
    2. Good Blood Supply
    3. Increase uptake of food - speeds up
    4. Millions in the Small Intestine
  2. Active Transport
    1. Hours after eating, there are more food molecules in your blood than in the small intestine
      1. Must force the remaining ones into the blood
8. Exchange in Plants
  1. Gas Exchange
    1. CO2 for Photosynthesis
    2. Oxygen is a by-product of Photosynthesis
    3. Stomata - Opened and closed by Guard Cells
    4. More Efficient on windy day - maintain concentration gradient
  2. Water and Ion uptake
    1. H2O for Photosynthesis
    2. Ions e.g. Magnesium used in Chlorophyll for photosynthesis
    3. Large Surface Area - Root hair cells
    4. Transport proteins present
9. Transpiration
  1. Water Evaporates from the leaves
    1. Low water pressure in leaves
      1. Pulls water from roots and stem upward
        Cycle will continue ->
  2. If needed, Guard Cells can close stomata to reduce water loss
Transporting Materials
1. Circulatory System and the Heart
  1. Double Circulation - oxygenated and deoxygenated
  2. Two pumps that beat in time
  3. Structure
    1. Vena Cava
      1. Right Atrium
        Right Ventricle
        Pulmonary Artery
        Pulmonary Vein
        Left Atrium
        Left Ventricle
        Aorta
2. Keeping the Blood Flowing
  1. Blood Vessels
    1. Arteries
      1. Away from Heart
    2. Vein
      1. INto the Heart
    3. Capillaries
      1. Very thin walls - diffusion of oxygen/Co2 + Glucose
  2. Stents - Force open the blood vessels
  3. Biological Valves
    1. No medication needed
    2. Lasts about 15 years
  4. Mechanical Valves
    1. Must take anticoagulants
    2. Lasts a lifetime
3. Transport in the Blood
  1. Oxygen <-> Oxygen + Haemoglobin
  2. Plasma - CO2, Urea
  3. White Blood Cells - fight infection
  4. Platelets - Clot the blood
4. Artificial or Real?
  1. Plasma or Saline
    1. Plasma carries dissolved oxygen and food
    2. Saline just replaces lost volume to buy time
  2. PFCs
    1. Can carry dissolved gasses around the body
      1. Do not dissolve in water - getting into blood is difficult
  3. Hearts
    1. uses air pressure to pump blood around the body
      1. Can live a normal life while waiting for transplant
5. Transport Systems in Plants
  1. Phloem - "Phood"
  2. Xylem - Water
  3. Mineral Ions are required for the production of proteins
  4. Water is needed for use in Photosynthesis
Keeping Internal Conditions Constant
1. Controlling internal conditions
  1. Removing Waste Products
    1. Carbon Dioxide
      1. Lungs
    2. Urea
      1. Kidneys
  2. The Kidneys Maintain the water and ion concentration within your body by filtering it out and reabsorbing what is needed
2. The Human Kidney
  1. Filter everything out (but NOT proteins - molecules too large)
  2. Reabsorb what's needed
  3. Urine (waste products, water and Urea), pass down the Ureter to the bladder
  4. Urine is stored in the bladder until it can be excreted
3. Dialysis (the Artificial Kidney)
  1. Blood is taken from the body and is passed through a machine
  2. Dialysis fluid containing the optimum levels of ions and water is passed next to a permeable membrane
  3. Diffusion takes place: Blood -> Dialysis fluid (needs to be replaced several times)
4. Kidney Transplants
  1. The rejection problem
    1. Could be attacked by immune system
    2. To reduce the risk, immunosuppressants are given
    3. Also to reduce the risk, the donors are tissue matched
  2. Finding Donors
    1. Never enough donors to go around
    2. Scientists are trying to...
      1. Genetically engineer pigs with suitable organs
      2. Use stem cells to grow new kidneys
  3. Dialysis v Transplant
    1. Must fit life around Dialysis
    2. Very little chance of a transplant
    3. Must take immunosuppressants with Transplant
5. Controlling body temperature
  1. Needs to stay at 37*
    Annotations:
    - * = degrees C
    1. Enzymes will denature
  2. Thermoregulatory centre monitors the temperature of your blood
    1. Iff too high, Sweating and vasodilation takes place
    2. If too low, Vasoconstriction, Less sweating, shivering - respiration and heat
6. Treatment and temperature issues
  1. Treating Kidney Failure
    1. In some developing countries, selling a Kidney is an option
    2. Dialysis/Transplant
  2. Too Cold: Hypothermia
  3. Too Hot: Heat stroke
7. Controlling Blood Glucose
  1. The Pancreas
    1. Too High - Insulin
      1. Converts Glucose into Glycogen
    2. Too Low - Glucagon
      1. Converts Glycogen into Glucose
8. Treating Diabetes
  1. Type 1
    1. Insulin Injections - Pancreas produces no insulin
    2. Transplants are possible, but only with immunosuppressants
  2. Type 2
    1. Pancreas doesn't produce enough insulin or type of insulin no longer effective
    2. Balanced Diet/Lose Weight/Exercise/Drugs/in drastic cases insulin
How Humans can affect the Environment
1. The effects of the population explosion
  1. Population has now exceeded 7 billion people
  2. Need more and more natural resources
  3. Producing more and more waste
    1. Industrial
      1. Toxic chemicals
    2. Domestic
      1. Sewage
2. Land and Water pollution
  1. Bioaccumulation Herbicides.Pesticides
  2. Fertilisers - we need more constant food supply for growing population
    1. Eutrophication
      1. "dead" pond
  3. Indicator Species - more pollutes less invertebrates
3. Air pollution
  1. Acid Rain
    1. Destroys certain types of stone
    2. Decreases pH of water e.g. rivers or reservoirs
  2. Global Dimming
    1. Tiny solid particles in atmosphere stop some of the sun's light - making it darker across the globe
4. Deforestation and peat destruction
5. Global Warming
6. Biofuels
7. Biogas
8. Making food production efficient
9. Sustainable food production
10. Environmental Issues

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Biology Unit 3 (AQA)

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	Created by Shaun Taylor 1998 about 9 years ago