Biology B3

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  • Biology B3
    • Exchange of materials
      • Osmosis
        • The random movement of water particles with the concentration gradient through a semi-permeable membrane from a high concentration to a low concentration
        • Water moves into cells via osmosis.
      • Gas and solute exchange
        • Substances move by active transport, diffusion and osmosis
        • Surfaces are adapted by having large surfaces areas, thin membranes and in animals, a good blood supply.
          • Villi
            • Has micro-villi for increased surface area
          • Alveoli
            • Single layer of surface cells which decreases distance for diffusion to occur
      • Active transport
        • Used to transport materials from areas of low concentration to a higher concentration, against the concentration gradient.
        • Used in humans in the kidneys for maximum glucose intake and in the gut for the same reason.
    • Breathing system
      • Ventilation is breathing in: Intercostal muscles and diaphragm contract, this causes the thorax volume to increase.
        • This decreases the pressure, drawing air IN
      • Exhalation is breathing out: Intercostal muscles and diaphragm relax, this causes the thorax volume to decrease
        • This increases the pressure in the lungs, forcing air OUT
    • Circulatory system
      • Heart
        • Double circulatory system
          • Lungs
          • rest of body
          • Journey of blood on separate mindmap
      • Blood vessels
        • Capillaries: One cell thick, carries blood to each individual cell, permeable walls to allow diffusion
        • Arteries: Carries blood under high pressure, has a thick wall size compared to lumen, thick elastic muscles to make them strong and spring back
        • Veins: Carries blood under low pressure, has a smaller lumen to wall size, has valves to make sure blood cannot return down the vein under the lower pressure
      • Components
        • Plasma
        • Red blood cells
        • White blood cells
        • Platelets
      • Circulation aids
        • Stents
          • A stent is a wire mesh that is inserted into an artery to generally squash a fatty deposit. The issues are that anti- clotting drugs must be taken otherwise there is the threat of a stroke
        • Artificial blood
          • The volume of blood can be topped up by adding a substance such as saline solution. However, this does not replace the red blood cells or carry out their function so a patient could still die. Other artificial bloods are being synthesized but they have side-effects.
        • Heart
          • Parts off the heart can be replaced with mechanical devices such as the heart valves. These have the same issues with clotting as stents do. Heart can also be transplanted but immune-suppressant drugs have to be taken to reduce chances of rejection
    • Homeostasis
      • Things that need to be controlled
        • Temperature
        • Water content
        • Glucose levels
        • Ion content
        • Urea levels
        • Carbon dioxide levels
      • Kidney
        • Water, glucose, urea and ions are excreted into the bowman's capsule
          • Along the nephron, all of the glucose, sufficient water and sufficient ions are reabsorbed back into the bloodstream
            • The waste ions a, water and all of the urea  travels down the collecting duct to be stored in the bladder before excretion.
        • Kidney failure
          • Kidney transplant
            • Whole kidney's can be transplanted from a live donor reduce chances of rejection we all have 2. However, immune-suppressant drugs are needed to s
          • Dialysis
            • The dialysis machine has a correct level of glucose, water and ions. It has no urea so urea in the patients blood diffuses across the machine's semi-permeable membrane. This greatly reduces urea levels but is expensive for the NHS.
    • Humans in the environment
      • Population is increasing rapidly. Resources are becoming limited.
      • Waste production is also increasing
      • Carbon dioxide
        • Stored naturally in the sea, peat bogs, green plants and fossil fuels
          • Pe3at is extracted for fuels and fertilisers. This releases stored CO2
        • When released into the atmosphere, Global warming- the trapping of light- occurs, heating up the planet.
      • Deforestation
        • Puts More methane in the air
        • reduces CO2 taken in and increases C02 given out
        • Less biodiversity. Due to habitat loss, the number of species in an area decreases, massively affecting the food chain.
      • Climate change
        • Global warming increases sea level, reduces biodiversity and disrupts migration patterns
      • Food production
        • Battery faming reduces energy lost by heat to speed up the time taken for the animal to mature.
        • People think battery farming is inhumane, The crowded conditions encourage disease, the animals are given antibiotics which can be passed on and to keep the animals warm, fossil fuels are burnt.
        • Fish stocks are decreasing so governments passed laws that increase the holes in nets and put in fishing quotas.
    • Biofuels
      • Biogas is made by anaerobic respiration of waste material
      • Ethanol is the fermentation of sugar anaerobically
      • Biogas generators are either batch or continuous. They can be small scale or large
        • Factors to consider are; Cost, Convenience, efficiency and position
      • Biofuels are carbon neutral. They take in as much CO2 as they give out

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