Biology 1 - Microscopes

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  • Biology 1
    • 1.1 World of the Microscope
      • Living things are made up of cells which are too small to see with a human eye so we use microscopes
      • You can calculate the magnification you are using by using the formula: EYEPIECE LENS X OBJECTIVE LENS =
      • Calculating the size of an object:   Magnification = SIZE OF REAL OBJECT ÷ SIZE OF REAL OBJECT
      • Resolution is the ability to distinguish between two separate points it is the resolving power of a microscope that affects how much detail it can show.
      • Microscope image
    • 1.2 Animal and Plant Cells
      • Animal Cells
        • NUCLEUS - controls the activities in the cell
        • CYTOPLASM - liquid gel in which organelles are suspended
        • CELL MEMBRANE - controls the passage of substances such as glucose and mineral irons into the cell
        • MITOCHONDRIA - structures in the cytoplasm where aerobic respiration takes place, releasing energy from the cell
        • RIBOSOMES - where protein synthesis takes place, making all the proteins needed in the cell
      • Plant Cells
        • ALGAE - simple aquatic organisms.
        • All plant and algal cells have a CELL WALL made of CELLULOSE that strengthens the cell and supports.
        • CHLOROPLASTS - found in all green parts of the plant because they contain the green substance CHLOROPHYLL.
        • CHLOROPHYLL - absorbs light so the plant can make food by photosynthe sis
        • PERMINENT VACUOLE - space in the cytoplasm filled with cell sap. This keeps cells rigid to support the plant
    • 1.3 EUKARYOTIC AND PROKARYO TIC CELLS
      • EUKARYOTIC CELLS - all have a cell membrane, cytoplasm, and genetic material enclosed in the nucleus
      • PROKARYO TIC CELLS - may also contain extra small rings of DNA called PLASMIDS
        • PLASMIDS are code for very specific features such as antibiotic resistance
      • ORDERS OF MAGNITUDE
        • Screen shot of the section in book
      • RELATIVE SIZES
        • Diagram screenshot
    • Using units screenshot
    • 1.4 AND 1.5 SPECIALISATION IN...
      • 1.5 PLANT
        • Root Hair Cells - help take up the water and mineral irons up the plant
          • Adaptations: Greatly increase surface area available,         Have a large permanent vacuole that speeds up movement,      Many mitochondria that transfer the energy needed for active transport
        • Photosyn thetic Cells -    Used for Photosyn thesis (making their own food)
          • Adaptations: Contain green structures called chloroplasts containing chlorophyll that trap light for photosyn thesis,              Are usually positioned in continuous layers of leaves to absorb lots of light,                Large permanent vacuole that helps keep the cell rigid as a result of osmosis
        • Phloem Cells - the specialised transport tissue that carries the food made by photosyn thesis
          • Adaptations: Cell walls between the cells break down to form special sieve plates. these allow water carrying dissolved food to move freely up and down the tubes,        Lose a lot of their internal structures but they are supported by companion cells that help to keep them alive.
      • 1.4 ANIMAL
        • Nerve Cells - they have adaptations including:  Lots of dendrites,    An axon that carries nerve impulse,      The nerve endings or synapse are adapted to pass the impulses to another cell
        • Muscle Cells - are specialised cells that can contract and relax.
          • They have adaptations including: Contain special proteins that slide over each oher making fibres contract,   They contain many mitochondria to transfer energy for reactions,    They store glycogen, a chemical which can be broken down and used in cellular respiration.
        • Sperm Cells - Adaptations include:         A long tail to help swim faster,        The middle section is full of mitochondria which transfers energy to the tail to work,      Acrosomes stores digestive enzymes for breaking down outer layers of egg,                 Large nucleus contains the genetic information to be passed on
      • As an organism develops, cells differentiate to form different types of specialised cells.
    • 1.6 DIFFUSION
      • Diffusion - The spreading out of the particles of gas or any substance in solution.
      • Rates of diffusion:   NET MOVEMENT = PARTICLES MOVING IN - PARTICLES MOVING OUT
      • Diffusion in living organisms - An increase in the surface area of a cell membrane means diffusion can take place quicker. This is an intestinal cell - magnification x 57 600
      • Dissolved substances such as glucose and urea and gases such as oxygen and carbon dioxide move in and out of cells by diffusion
    • 1.7 OSMOSIS
      • 1.8 OSMOSIS IN PLANTS
        • Osmosis is important to maintain turgor in plant cells
        • There are a variety of practical investigations that can be used to show the effect of osmosis on plant tissue
      • Osmosis is a special case of diffusion. It is the movement of water from a dilute to a more concentrated solution through a partially permeable membrane that allows water to pass through.
      • Differences in the concentrations of the solutions inside and outside a cell cause water to move into or out of the cell by osmosis
      • Animal cells can be damaged if the concentration outside the cell changes dramatically
    • 1.9 ACTIVE TRANSPORT
      • Active Transport moves substances from a more dilute solution to a more concentrated solution
      • ... Uses energy released from food in respiration to provide the energy required
      • ... Allows plant root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil
      • ... enables sugar molecules used for cell respiration to be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is higher
    • 1.10 EXCHANGING MATERIALS
      • Single-celled organisms have a relatively large surface area to volume ratio so all necessary exchanges with the environment take place over this surface
      • In multi cellular organisms, many organs are specialised with effective exchange surfaces
      • Exchange surfaces usually have a large surface area and thin walls, which give short diffusion distances. In animals, exchange surfaces will have an efficient blood supply or, for gaseous exchange, be ventilated

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