Biology Unit one

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  • Biology unit 1
    • Diet and metabolic rate
      • A balanced diet.
        • Carbohydrates release energy
        • Fat keeps you warm and releases energy
        • protein is used for growth, cell repair and cell replacement
        • Fibre keeps everything running smoothly in your digestive system
        • Vitamins and minerals keep your skin, bones, blood and everything generally healthy
      • Factors affecting health
        • Obesity, eating too much leading to excess carbohydrates and fats and lack of exercise
        • Malnourishment, can lead to slow growth, fatigue, poor resistance and irregular periods
        • Not getting enough exercise. Doing exercise increases the amount of energy used and decreases the amount stored as fat
        • Inherited factors which effect their metabolic rate.
    • Fighting disease
      • Pathogens
        • Bacteria: very small living cells which rapidly reproduce in the body. They damage your cells and produce toxins
        • Viruses: not cells but they replicate themselves by invading your cells, the cells usually then burst. This makes you feel ill.
      • Defences
        • Consuming them: White blood cells engulf foreign cells and digest them
        • Antibodies are produced: these are proteins which lock onto the certain pathogen, these are produced rapidly
        • Producing anti-toxins, these counteract the toxins produced by the invading bacteria
      • Vaccinations involve injecting the dead or inactive version of the microorganism, your body them produces antibodies and your memory cells remember the antibodies needed to kill that pathogen.
      • drugs
        • Some just relieve symptoms eg. painkillers
        • Bacteria can become resistant to antibiotics, they can mutate
    • The nervous system
      • Sense organs
        • Eyes, light receptors
        • Ears, sound receptors
        • Nose, smell receptor
        • Skin, touch receptor
      • The reflex arc
        • STIMULUS -> RECEPTOR -> SENSORY NEURON -> RELAY NEURON ->  MOTOR NEURON -> EFFECTOR -> RESPONSE
      • Synapses
        • connect neurons, the nerve signal is transferred by chemicals which diffuse across
    • Hormones
      • Chemical messengers sent in the blood
      • Plant hormones
        • auxin is a plant growth hormone in response to:
          • light (phototropism), when the shoot tip is exposed to light, more auxin accumulates on the shaded side
          • Gravity (geotrophism) shoots grow away from gravity
            • Roots grow towards gravity
          • Moisture, roots grow towards moisture,more moisture inhibits growth making it bend towards the moisture
    • The menstrual cycle
      • Hormones involved
        • FSH: produced by the pituitary gland, causes the egg to mature and stimulates the ovaries to produce oestrogen
        • Oestrogen: produced by the ovaries, causes the pituitary to produce LH, inhibits further release of FSH
        • LH: produced by the pituitaryy gland stimulates the release of an egg
      • The four stages
        • Stage 1: the bleeding starts, uterus lining breaks down
        • Stage 2: lining of the uterus build up again
        • Stage 3: an egg is released
        • Stage 4: the wall is maintained
    • Homeostasis
      • the maintenance of a constant internal enviroment
      • Ion content, water content, sugar content and temperature
    • Drugs
      • change your body chemistry
      • Performance enhancing
        • can cause high blood pressure
        • some are illegal whilst others arent
      • medicinal drugs
        • testing: tested on human cells in the lab, then on live animals, then human volunteers
      • recreational drugs
        • legal and illegal
        • put into categories such as class A, B and C
        • some legal drugs have a bigger impact such as nicotine
    • Adaptations
      • desert animals have adapted to save water and keep cool
      • Arctic animals have adapted to reduce heat loss
      • desert plant have adapted to having little water
      • some animals and plants are adapted to deter predators
      • Extremophiles are micro-organisms that can live in extreme conditions
    • Competition and Environmental change
      • Plants compete for light, space, water and minerals
      • animals compete for territory, food, water and mates
      • enviromental changes are effected by living and non living factors
        • living
          • infectious diseases
          • number of predators
          • number of prey and food sources
          • number of competators
        • non living
          • change in average temperature
          • change in average rainfall
          • change in level of air and water pollution
      • measuring environmental change
        • indicator species
        • satellites
        • rain gauges
    • energy transfer and decay
      • most biomass and energy is lost through food chains via respiration etc
      • elements are cycled back when they decay
    • the carbon cycle
      • powered by photosynthesis
      • some CO2 is returned to the atmosphere via respiration
      • fossil fuels burnt and put back into the air
    • Variation
      • Characterists due to both the genes and environment
    • genes, chromosomes and DNA
      • inside cells theres a nucleus which contains 23 pairs of chromosomes
      • chromosomes carry genes
      • DNA is coiled up to form the arms of chromosomes
    • Reproduction
      • sexual reproduction involves the fusion of a female and male gamete, there are two parents
      • Asexual reproduction involves one parent, the offspring are genetically identical to the parent
    • Cloning
      • plants
        • Tissue culture
          • take a few plant cells, put in a growth medium with hormones
        • cuttings
          • take a cutting then plant it
      • animals
        • embryo transplant
          • sperm cells and egg taken from parents, embryo is split and put into many mothers
        • adult cell cloning
          • egg cell taken, nucleus removed and nucleus from body cell is inserted, then given an electric shock then implanted
    • Genetic engineering
      • GM crops
        • genes modified to suit what the farmer wants
    • Evolution
      • Charles Darwin Natural selection
        • the better adapted survived and passed genes on
      • Lamarck thought that the characteristic most used would be passed down

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