Biology unit 1 (AQA GCSE)

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  • Biology (AQA)
    • DNA
      • They consist of long strands of DNA
      • The gene is the unit of inheritance and each chromosone has thousands of genes in it.
        • http://www.bbc.co.uk/staticarchive/678f62dce35d0fc7ef2333d6d3bfbf53744374ff.jpg
      • The genes on those chromosomes carry the code that determines our physical characteristics, which are a combination of those of our two parents.
    • Decay
      • The main groups of decomposer organisms are bacteria and fungi
      • They both cause decay by releasing enzymes which break down compounds in their food so it can be absorbed by their cells.
      • The factors that affect decay rate are moisture, temperature and amount of available oxygen
      • http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/energy_biomass/thecarboncyclerev1.shtml
    • Reproduction
      • Sexual
        • Sex cells are called gametes
          • Male sex cells: sperm
          • Female sex cells: eggs or ova
      • Asexual
        • Asexual reproduction is a type of reproduction where  offspring arise from a single organism, and inherit the genes of that parent only; it does not involve the fusion of gametes
          • Plants
            • http://www.bbc.co.uk/staticarchive/5aaa8b345a205395c996e69fa812f8f92949ceb5.gif
              • -------->  Example of Asexual reproduction in plants.
          • Animals
            • http://www.bbc.co.uk/staticarchive/9c7cc8f9772c8e1087f3da7b1affa4c00bb5109c.gif
              • --------> Example of fusion cell cloning
    • Evolution
      • Charles Darwin
        • Darwin believed that we evolved from apes
          • He got this idea from when he saw the same species of bird with different types of beak.
          • Scientists ridiculed him because :
            • Darwin's theory conflicted with religious beliefs that God put all animals and plants on Earth.
            • Darwin did not have enough evidence at the time to convince many scientists
            • t took 50 years after Darwin’s theory was published to discover how inheritance and variation worked.
      • Jean-Baptiste Lamarck
        • A characteristic which is used more and more by an organism become bigger and stronger and one that is not used eventually disappears.
        • Any feature of an organism that is improved through use ispassed on to its offspring.
          • An example would be that Lamark thought that giraffes had long necks due to them trying to reach up to get it, which stretched their neck and the gene of a longer neck was passed on to the offspring.
            • A characteristic which is used more and more by an organism become bigger and stronger and one that is not used eventually disappears.
      • Natural Selection
        • individuals in a species show a wide range of variation
        • this variation is because of differences in their genes
        • individuals with characteristics most suited to the environment are more likely to survive and reproduce
        • the genes that allow these individuals to be successful are passed to their offspring.
    • The Carbon Cycle
      • Visit these links to understand
        • http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/energy_biomass/thecarboncyclerev2.shtml
          • GCSE Bitesize
        • Slideshow:
          • http://www.slideshare.net/kumartekchandani/carbon-cycle-14155695
    • Cells
      • Animal
        • Nucleus: controls activities of the cell.
        • Cytoplasm: where chemical reactions take place.
        • Cell membrane: controls passage of substances in and out of the cell.
        • Mitachondria: aerobic respiration
        • ribosomes: protein synthesis
      • Plant
        • The same as the animal cells with added features
        • Cell wall: strengthens cell.
        • Chloroplasts: used for photosynthesis.
        • Vacuole: filled with liquid sap
      • Bacterial
        • Same as animal cells.
        • cytoplasm, membrane surrounded by cell wall.
        • DNA isn't stored in nucleus.
      • Yest
        • Nucleus, cytoplasm, membrane surrounded by cell wall.
      • Special cells
        • Sperm cell
          • To fertilise the egg. carries half the genetic information
            • Tail to swim to egg. Pointed head to burrow into the egg. mitochondria to provide energy.
        • Muscle cell
          • Used for movement
            • Special proteins which contract and relax
        • Nerve cell
          • To carry nerve impulses about stimuli around the body & impulses that muscles contact.
            • Long axon to reduce number of nerve cells. Long axon to cover with fatty tissue to speed up nerve impulses.
        • Root hair cell
          • Absorb water water into plant roots
            • Large surface area to long tube shaped membrane to take in more water
        • Xylem cell
          • Carries water through plant stems&leaves
            • Long hollow tube, lingin makes strong.
        • Ploem cell
          • Carries sugar through plant stems.
            • Long hollow cells, end wall (sieve plates) holes for sugar to pass through.
  • Fertilisation begins when these two meet

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