Biology unit 3

Sums up the whole of the new spec. unit 3

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  • Created by: Louisa
  • Created on: 06-05-13 09:42


  • Net movement of water from an area of high concentration to an area of low concentration across a partcially permeable membrane

Osmosis in Animals

  • Cytoplasm becomes more concentrated
  • Water moves into the cell by osmosis
  • Water moves into the cell by osmosis
  • Cytoplasm becomes too dilute
  • Water moves out of the cell by osmosis

Osmosis in Plants

  • Support stems and leaves - Water in vacuole presses cytoplasm into cell wall - cell rigid
  • Surrounding cell higher conc. than the cell cytoplasm - if not water out by osmosis
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Active Transport

  • allows cells to move substances from an area of low concentration to an area of high concentration against a concentration gradient
  • This process uses energy from the cells in the mitochondria
  • Energy comes from cellular respiration
  • Rate of respiration against rate of active transport is closely linked

Use of Active Transport in Plants

  • mineral ions in soil (low conc.) move into plant against conc. gradient into the plant with a high conc. of mineral ions

Use of Active transport in Animals

  • Glucose absorbed out of your gut and kidney tubules into your blood. (large conc. gradient)
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Sports Drinks

  • Contain sugar to replace energy during exercise.
  • Replace mineral ions and water lost in sweating
  • Cells become dehydrated during exercise
  • Sports drinks contain water to rehydrate the cells
  • isotonic drinks are not needed for short term exercise
  • Water will keep your cells hydrated as well as sports drinks
  • Orange squash will replace sugar
  • A pinch of salt in the orange squash will replace mineral ions lost
  • Milk is one of the most effective way of replacing sugars, salts and mineral ions lost when you exercise and provides protein and vitamins as well
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Exchanging Materials - the Lungs

  • bigger complex organisms- surface area:volume gets smaller

Lung adaptions

  • Clusters of alveoli - Large surface area - effective diffusion, rich blood supply - maintains concentration gradient, thin walls - short diffusion path

Adaptions of Exchange Surfaces

  • large surface area
  • short diffusion path
  • steep concentration gradient
  • efficient blood supply - maintains conc. gradient
  • Ventilation - maintains con. gradient
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Ventilating the lungs

  • Steep concentration gradient is needed for gas exchange

Breathing System

  • Lungs found in thorax
  • Seperate from digestive system - diaphragm seperates these two systems
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Artificial Breathing Aids

Why are they needed?

  • Tubes to lungs narrowed so less air gets to the lungs
  • Structure of alveoli has broken down
  • Paralysis

Negative Pressure

  • polio sufferers
  • metal cylinder - tight seal round neck
  • air out - lower pressure, chest wall rises (incresed volume/decreased pressure in chest)
  • air in -increase pressure, rib down (decreased volume/increased pressure in chest)

Positive pressure

  • Measure air in/ simple face mask/ emergency or in surgery/ no big machine/ use at home/ can move around/ (modern) linked to computer.
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Exchange in the Gut

  • Food broken down in the gut
  • Food ---(GUT)--- Glucose, amino acids, fatty acids, gycerol --- fuel for respiration, growth and repair
  • Successful exchange surface needed
  • Absorbtion in the small intestine
  • diffusion and active transport
  • Move freely thorugh the wall of the gut - steep concentration gradient
  • VILLI - increase uptake of food by diffusion
  • VILLI - increased surface area
  • MICROVILLI on the VILLI - increase surface area
  • Active transport inthe small intestine
  • small intestine to the blood - active transport
  • no digested food is wasted
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Exchange in Plants

  • Plants rely heavily on diffusion to get the carbon dioxide needed for photosythesis
  • Osmosis to take up the water form the soil
  • Active transport to obtain mineral ions from the soil
  • Gas  exchange in plants
  • Leafs flattened shape increases surface area for diffusion
  • Leafs air spaces for CO2 to come in contact with lots of cells - increases surface area further
  • Leafs lose water from leaves by evapouration
  • Adapted to allow CO2 to enter nly when needed - stomata which open and close
  • Stomata also allow oxygen to enter
  • Guard cells controls the opening and closing of the stomata
  • Upatke of mineral ions
  • Root hair cells
  • large surface area
  • Xylem moves up the plant
  • Mitochondria for supplying energy for active transport
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Water loss from leaves

  • When stomata open for CO2 to enter water is lost
  • As water is lost water is pulled up to replace water lost
  • constant movement of water up the xylem from roots to leaves is transpiration stream
  • Transpiration is driven by evapouration of water

Effect of environment on transpiration

  • sunny conditions increase the rate of transpiration

Controlling water loss

  • Wilting - surface area reduced so less water lost


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The Circulatory System and The Heart

  • Transport system - blood circulation system
  • The pipes - Blood vessels
  • The pump - The heart
  • The liquid - The Blood

DOUBLE CIRCULATION - Heart to lungs, Lungs to Heart, Heart to Body, Body to Heart.

Arteries - Blood away from Heart   Veins - Blood Returned to Heart

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Blood Vessels

  • Arteries
  • Carry blood away from the heart
  • bright red and oxygenated
  • Stretch as blood goes through - pulse
  • Blood is under pressure - very dangerous is cut
  • Veins
  • Carry blodd towards Heart
  • Low in oxygen - purply-red
  • No pulse
  • Valves - prevent backflow of blood
  • Capillaries
  • Network of tiny vessels that link arteries and veins
  • Very thin walls - short diffusion path for substances to dissolve into blood
  • Stents
  • placed in narrow vessels to allow blood to flow freely
  • Valves
  • If you have a faulty valve it can be replaced - biological or mechanical 
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Transport in the Blood


  • Tranports blood cells and urea from kidneys (waste form break down of proteins)
  • Carries food molecules to cells and organs

Red blood cells

  • Carry oxygen from lungs
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Villi with Microvilli

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Artificial or Real?

  • Artificial Blood
  • Blood tranfusions can replace any blood lost - have to match blood group
  • Blood can only be stored for a short time - small amounts of donors
  • Plasma or Saline
  • plasma - carries little dissolved oxygen
  • Saline (salt water) - doesn't carry oxygen, keeps volume to keep pressure normal.
  • These can buy time for your body to make blood or a matched blood transfusion
  • Perfluorocarbons (PFC's)
  • Non-reactive chemicals that carry dissolved gases around the body
  • PFC's don't contain cells so can get through squashed capillaries
  • Kept for a long time and don't carry disease, Don't dissolve in water so hard to get into the blood
  • High amounts becasue can't carry as much oxygen, broken down quickly, can cause severe side-effects
  • Haemoglobin
  • Doens't contain red blood cells, made sythetically or genetically engineered
  • Casrries more oxygen than normal blood, Doesn't clot or fight disease, doesn't have to be kept in a fridge
  • Artificial Hearts
  • No wait for a donor, No need for a match of tissue, no need for immunosupprensant drugs
  • Problems with blood clotting, Staying in hospital, Expensive.
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Transport Systems in Plants

  • Phloem
  • Transport sugars made by photosythesis all over the plant
  • Food is transported to storage organs
  • Living tissue
  • Greenfly and aphids pest feed on the sugary fluid
  • Xylem
  • Mature xylem cells are dead
  • In woody plants the xylem makes the bulk of the wood
  • Phloem is the ring underneath the bark making young trees vunerable
  • Why is it so important
  • Need sugar for respiration and materials for growth.
  • Mineral ions for production of proteins and othe rmolecules in the cells
  • Water is needed for photosythesis and structural properties - main method of support in soft stemmed plants


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Controlling Internal Conditions

  • As surroundings change cells must stay as constant as possible
  • HOMEOSTASIS - controls the internal conditions of the body
  • Removing Waste Products
  • Waste products are the products of the chemical reactions that take place in the cells
  • More extreme conditions the more waste products produced
  • Main poisonous wastes - Carbon dioxide and urea
  • dangerous if they build up
  • Carbon Dioxide
  • Produced during respiration
  • Produces acidic solution if built up
  • Affects the working of enzymes as they are responsive to pH
  • CO2 moves out of your cells into the blood
  • The bloodstream takes it to the lungs where it is breathed out into the atmosphere
  • Urea
  • Liver removes excess protein (amino acids) converts it to urea
  • Urea passed form the liver intot he blood is then filtered out by the kidneys
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The Human Kidney

  • Invloved in excretion
  • Filters poisonous urea and removes it in the urine and stored temporarily in bladder
  • Vital in water balance of the body - you lose water from breathing and sweating
  • Short of water - kidneys conserve it - produce little urine
  • Excess Water - kidneys produces a lot of urine
  • Control mineral ion balance
  • too much salt or other minerals - removed in urine
  • How kidneys work
  • Filter the blood
  • Reabsorb everything your body needs
  • Sugar, amino acids, minerla ions, urea and water all move out of your blood into the kidney tubules (move by diffusion along a concentration gradient)
  • The blood cells andlarge molecules are left behind - too big too pass through the membrane of the tubule
  • The sugar is reabsorbed into the blood by active transport
  • The amount of water and mineral ions are reabsorbed depending on what the body needs - this is called SELECTIVE REABSORBTION
  • Some urea is reabsorbed into the blood


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Dialysis - An Artificial Kidney

  • used if you have kidney faliure
  • methods of treating kidney failure - dialysis or transplant


  • Restores concentration of dissolved substances in the blood
  • Dialysis repeated several times a week
  • 8 hours for dialysis to take place
  • Patients need to manage their diet very carefully
  • over many years balance becomes more difficult to control
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Kidney Transpants

Kidney inserted by a donor organ

joined to blood vessels in groin of the recipient

One kidney can balance blood chemistry and remove waste urea for a lifetime

Problem with rejection - proteins (antigens) on surface of cells are different therefore the immune system may attack the organ

To reduce the risk of rejection you can make sure the tissue match is very close and using immunosuppressant drugs

The problem with immunosuppressant drugs are they reduce effectiveness of the immune system and prevent them attacking bacteria and viruses

Transplanted kidneys don't last forever - at least 9 years when they run out patient referred back to dialysis treatment

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Controlling Body Temperature


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Treatment and Temperature Issues

  • In some developing countries people will sell one of their kidneys they need the money to pay for food, medicine or education or education for their families.
  • Many families who lose a loved one give their consent for an organ donation. Knowing their loss has given others life is a real comfort at a terrible time
  • Both transplant and dialysis cost a lot of money.
  • Hypothermia is when you rbody temperature falls below 35'C
  • Heat stroke is when you can't lose energy so you fall into a coma and die
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Controlling Blood Glucose

Glucose - A sugar found in the blood

Glucogen - a storage carbohydrate found in the liver and muscles

Glucagon - A hormone

  • Insulin controls blood sugar levels.
  • Types 1 diabetes is when the prancreas does not make enough or any insulin
  • Insulin is aprotein so it would be digested in the stomach so it is injected into the bloodstream
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Treating Diabetes

  • Genetic engineering has been used to develop bacteria that produces human insulin

Type 1 Diabetes

  • Doctors have tranplanted pancreases but the operation is difficult and risky and the patient still has to take medicine (immunosuppresants instead of insulin)
  • Transplanting pancreatic cells that produce insulin from both living and dead donors has been tries with little success
  • Embryonic Stem Cells differenciate to pancreatic cells that produce insulin

Type 2 Diabetes

  • From lack of exercise and obesity
  • Pancreas makes less insulin and cells don't respond to insulin
  • Restoring normal glucose balance by eating a balanced diet, losing weight and exercising
  • There are drugs that help cells to respond to insulin, make more insulin and reduce amount of glucose absorbed in the gut
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The Effects of Humans on the Environment

  • Human population growth has increased massivly over 200years
  • Predators lack of food, build up of waste products or diseases would reduce the population again.
  • We have no natural predators, discovered how to cure disease and grow food
  • Standard of living has improved
  • Use vast amounts of electricity and fuel from fossil fuels, oil and oil-based fuels
  • More than enough to eat and if we are ill be can often be made better
  • Increased number of people has a big effect on environment as we need homes to live
  • Land is being used for buildings which destroy habitats of animals
  • Quarrying destroys large areas of land which reduces land available for othe organisms
  • Billions of acres are used for farming meaning animal and plants are being destroyed
  • Draining the resources of the earth
  • Raw Materials are being used up (non-renewable energy resources e.g. oil and gas)
  • Metal ores are being used up
  • Increased amount of waste produced
  • Ever growign population continues to affect the ECOLOGY of the earth
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Land and Water Pollution

  • More waste produced

Land Pollution

  • Sewage waste can pollute the land with unpleasant chemicals and gut parasites
  • Landfill sites can spread toxic chemicals from the waste into the soil
  • Farmers use fertilisers and herbicides to kill pests which are poisonous to the environment
  • The chemicals in the soil from fertilisers can enter the food chain and build up to dangerous levels

Water Pollution

  • nitrates washed into the rivers, ponds and streams
  • The chemicals in the soil from fertilisers can enter the aquatic food chain and build up to dangerous levels
  • BIOINDICATORS - used to monitor pollution levels
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Air Pollution

  • Fossil fuels burning to produced sulfur dioxide
  • Sulfur dioxide gas dissolved in the rainwater and produces acid rain
  • Damages environment
  • Can kill trees if it falls on it and the roots as well
  • Ecosystem can be destroyed
  • Acid rain falling into lakes can become too concentrated to sustain life
  • Acid rain in blown onto other countries that it is picked up from
  • Cars are fitted with catalytical converters that stop the release of sulfur dioixde
  • increase number of tiny solid partices in the air
  • Sulfur particles reflect light so less light hits the earth
  • Cooling temperatures at the surface of the earth
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Deforestation and Peat Destruction

  • Forsts destroyed for farming, buildings and fuel
  • SLASH AND BURN - tree's felled and then burnt to make fertile land for a short time
  • No trees planted to replace those cut down
  • Increased CO2 in environment
  • Loss of biodiversity
  • Species of animals and plants die out because of loss of habitat
  • When forests clear they are replaced by a monoculture such as oil palms
  • Cows, Rice and Methane
  • When forests are cut down sometimes land used for cows and rice paddies
  • Cows and rice paddies release methane that can be used as fuel
  • Peat Bogs
  • Formed over thousands of years in marshy areas
  • Plant matter that cannot decay - conditions acidic and lack oxygen
  • Massive Carbon Store
  • Burnt as fuel
  • Used to improve soil properties
  • Use compost as alternate
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Global Warming

  • Global Warming
  • Carbon Dioxide is sequestered in plants and waters or act as carbon dioxide sinks
  • Humans - increase of CO2 and methane levels
  • GREENHOUSE EFFECT - CO2 absorbs heat radiation from sun heating atmosphere
  • Change in one degree - big changes in earths climate
  • Change in one degree - rise in sea levels
  • Change in one degree - reduced biodiversity
  • Change in one degree - changes in migration patterns
  • Change in one degree - changes in distribution
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  • Re-newable form of fuel
  • made from natural productions by fermentation using yeast or bacteria
  • Ethanol based fuels and biogas
  • Sugar cane and maize fermented anaerobically with yeast; distill it and use it as fuel
  • Efficient, less polluting
  • Can mix with other fuels to make GASOHOL - reduces pollution levels considerably
  • Carbon Neutral
  • Takes a lot of plant material to produce it - could be used for food
  • Needs a lot of space to make and suitable climate
  • Looking at fast growing grasses - looked at pine and beet - not successful
  • Need to find cellulose rich biomass rather than edible parts of plants
  • Latest technologies - enzymes steam or chmical treatments to break down cellulose biomass
  • Straw and woodchips as raw materials - end products sugar that can be fermented and distilled
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  • Becoming more important as non-renewable sources are running out
  • Flammable mixture of gases - formed when bacteria break down plant material or waste products of animals in anaerobic conditions
  • Biogas is mainly methane - Can be used for heating
  • Biogas generators - bacteria that break down waste work at 30'C - hot countries
  • process in biogas generators are EXOTHERMIC
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Efficient Food Production

  • Pyramids of biomass show that each successive stage contains less energy
  • Diet mostly contains meat or other animal products
  • By the time it reaches us for food it supplys little energy
  • Most energy efficient is grow plants and eat them
  • Artificially Managed Food production - limit movement of animals, control temp of surrounding to reduce energy waste
  • Higher risk of disease
  • Only way that farmers can meet the demands of the consumers
  • Food miles - efficient depending on how it travels - release of CO2 in atmosphere
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Sustainable Food Production

  • Producing food in ways that can contine for many years
  • Maintains health of of soil and taking care of fish so they don't run out
  • Banning fishing in breeding season
  • Smaller nets
  • Strict quotas on fishermen
  • Limited on amount and type of fish they are allowed to catch
  • Mycroprotein Production - Protein form fungus - Fusarium
  • Arobic conditions to double its mass every five hours
  • high protein low fat meat substitute
  • Very sustainable
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Environmental Issues

  • Dams destroy river ecosystems
  • food plains with fertile soils disappear less farming producing food
  • Environments destroyed
  • Reservoirs act as breeding ground for mosquitos that carry diseases
  • May add methane to the environment as EUTROPHICATION can occur
  • VALID REPRODUCABLE REPEATABLE the data about the environment is
  • Somenot to be trusted
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What does Urine Contain

  • Depends on on what you do and tke in
  • Hot day - drink little and exercise a lot - will produce very little urine - dark yellow (conc.)
  • Cold day - drink a lot and do little - will produce a lot - colourless
  • Water, glucose, urea and salt are colourless but urine is yellow
  • UROBILINS - make urine yellow
  • UROBILINS - From breakdown of haemoglobin in the liver
  • UROBILIN - exreted by your kidneys in the urine along with everything else making it yellow
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What does Urine Contain

  • Depends on on what you do and tke in
  • Hot day - drink little and exercise a lot - will produce very little urine - dark yellow (conc.)
  • Cold day - drink a lot and do little - will produce a lot - colourless
  • Water, glucose, urea and salt are colourless but urine is yellow
  • UROBILINS - make urine yellow
  • UROBILINS - From breakdown of haemoglobin in the liver
  • UROBILIN - exreted by your kidneys in the urine along with everything else making it yellow
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