Biology unit 2

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  • B2
    • Respiration
    • Cells
      • Animal cells
        • Nucleus
          • controls cell activity
        • Cytoplasm
          • Where most chemical reactions take place
        • Mitochondria
          • Most energy is released by respiration here
        • Cell membrane
          • Controls the movement of substance in and out the cell
        • Ribosomes
          • When protein synthesis takes place
      • Plant cells
        • cell wall
          • Strengthens the cell
        • chloroplasts
          • Contain chlorophyll which helps plant absorb light in photosynthesis
        • permanent vacuole
          • filled with cell sap
      • Bacterial cells
        • Do not include a nucleus
        • A single celled organism
        • Has cytoplasm, cell wall and cell membrane
      • Yeast
        • Have cell wall, membrane, cytoplasm and nucleus
    • Tissues, organs and organ systems
      • Multicellur organisms  usually contain differentiated cells adapted for specific functions
        • Tissues consist of a group of similar cells working together.
          • muscular
            • helps muscles contract and bring movement
              • churns food in the stomach and other contents
          • Glandular
            • Produces substances like enzymes and hormones
              • produces digestive juices like acids and enzymes
                • Pancreas and salivary glands
          • epithelial
            • covers some parts of body
              • covers inner and outer surfaces of stomach
          • liver
            • produces bile which emulsifies fats so they are prepared for digestion
          • small intenstine
            • digests and absorbs soluble food
          • Large intestine
            • absorbs water from insoluble food producing faeces
      • Organs contain different tissues that work together to perform functions
      • Differentiationis when cells become a specialized cell
    • Proteins-their functions and uses
      • Proteins are made from long chains of smaller molecules called amino acids
        • Enzymes are biological catalysts  and also proteins
          • If the shape of the enzyme has been changed then it may no longer work and denatures.
          • There activity is greatest at their optimum temperatures and pH values
          • structural components of tissues(such as muscles)
          • Hormones such as insulin
          • Antibodies-part of the bodies immune system
          • Biological catalysts
            • Increase the rate of chemical reactions without being used up
              • Enzymes allow smaller molecules to fit into them. The place where a substrate molecule fits is called the active site.
                • Enzymes can be denatured by high temperatures or extreme pH
          • The digestive system
            • Amylase turns starch into sugars
              • Salivary glands, pancreas and small intestine
            • Pro tease turns protein into amino acids
              • Stomach, Pancreas and small intestine
              • Breaks down proteins
                • Protease is used in baby food to pre digest the proteins
            • Lipase turns lipid into fatty acids and glycerol
              • Pancreas and small intestine
                • Breaks down fats
            • Bile nuetralises acidic food in the small intestine
              • Produced by liver and stored in the gall bladder
            • Carbohydrase
              • Breaks down carbs
                • used to convert starch syrup used for sport drinks
            • Imsomerase
              • used to convert glucose syrup into fructose syrup. used in slimming foods
    • Organisms and their environment
      • Factors affecting distribution of organisms
        • Temperature
        • Amount of light
        • Available water
        • Available nutrients
        • Availability of oxygen and carbon dioxide
        • Transects are a line that is placed across a certain area measuring the distribution of organisms
        • Quadrats are squares used for random sampling or placed along a transect
          • The validity increases along with the reproducible when the results from the quadrats are analysed
    • speciation
      • The fossil record is incomplete. There is a good fossil record for the evolution of the horse
        • The horse evolved its feet as the horse used to be the size of a dog and have multiple toes however as evolution occurred the horse's feet changed into single-toed hooves suitable for running.
      • Fossils are the preserved or traces of dead organisms
        • The fossil record is incomplete. There is a good fossil record for the evolution of the horse
          • The horse evolved its feet as the horse used to be the size of a dog and have multiple toes however as evolution occurred the horse's feet changed into single-toed hooves suitable for running.
        • Fossils can be formed from:
          • Hard body parts such as bones and shells which cannot decay easily or are replaced by other materials as they decay
          • Parts of organisms that have not decayed. These can be preserved in hardened tree resin, ice,tar pits or peat  bogs
          • Casts or impressions such as footprints or burrows. These can become covered by layers of sediment which eventually become rock.
      • Individuals who are more adapted to their environment are more likely to survive. Species that aren't adapted to their environment may become extinct
        • some factors can cause species to become extinct
          • New diseases
          • New predators
          • New competitors
          • Changes to the environment
          • A catastrophic event
      • Speciation is the form of new species in the course of evolution
      • New species can form if they become isolated.Two populations of a species can become separated.
        • New species can arise as a result of
          • Genetic variation- where a population has a large range of alleles that control their characteristics
          • Natural selection
          • speciation- where the populations become so different they cannot interbreed.
    • Cell division and inheritenance

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