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biology (living organisms share the following characteristics (require…

- - - - living material that makes up cell
    - - contains chromosomes which carry genes, which control the activities in the cell by determining which proteins can make
    - - where proteins are assembled, tiny structures, thousands in one cell
    - - surrounds all cells, forms boundary between cytoplasm of cell and outside,
      - partially permeable, some chemicals can pass through
        
        can control movement of some substances, selectively permeable
    - - layer of non-living material found outside cell membrane of plant cells
      - mainly made of cellulose
      - plant cells absorb water producing an internal pressure that pushes against pushes against adjacent cells, giving plant support
        
        cell wall required to resist these pressure
      - freely permeable
    - - found in cytoplasm of all living cells
      - carry out some of the reactions of respiration
        
        more found in cells requiring more energy
    - - absorb light energy to make food in the process of photosynthesis
      - contain green pigment called chlorophyll
      - non green parts of plants have no chloroplasts
    - - permanent feature of plant cells
      - filled with watery liquid called cell sap
        
        store of dissolved sugars mineral ions and other solutes
  - - - collections of several tissues carrying out a particular function is called an organ
        
        in animals jobs are usually carried out by different organs working together, this is called an organ system
  - - - plant cells have which animal cell do not
        
        permanent vacuole
        
        cell wall
        
        chloroplasts
    - - nucleus
      - cell membrane
      - mitochondria
      - cytoplasm
- - - - in a cell atp can be broken down losing one phosphate group and forming adenosine diphosphate
        
        when this reaction takes place chemical energy is released and can be used to drive metabolic processes that need it
        
        during respiration the reverse happens, energy from the oxidation of glucose is used to drive the reverse reaction and a phosphate is added onto adp
  - - - anaerobic respiration is respiration without the use of oxygen
      - in anaerobic respiration the glucose is not fully broken down so less energy is released
      - anaerobic respiration can occur in places where oxygen is in short supply
      - anaerobic exercise causes lactic acid to build up which needs oxygen to be cleared, this is called oxygen debt
    - - aerobic
        
        C6H12O6 + 602 -------> 6CO2 + 6H20
        
        glucose + oxygen -----> carbon dioxide + water
      - anaerobic
        
        plants
        
        glucose ------> ethanol + carbon dioxide
        
        animals
        
        C6H12O6 ------> 2C3H6O3
        
        glucose------>lactic acid
  - - - disinfect peas
        
        place each set in inverted vacuum flask, leaving some air, insert thermometer and fill gap with cotton wool
        
        measure temperature
- - - - happens when a substance is more concentrated in one place than another
        
        this difference in concentration is called a concentration gradient
        
        molecules are constantly moving due to their kinetic energy
        
        due to concentration gradient particles will have net movement to area of low concentration
      - rate affected by 4 factors
        
        concentration gradient
        
        happens more quickly when this is steeper
        
        sa to volume ratio
        
        large surface area in proportion to volume will increase rate
        
        distance
        
        rate decreases if distance to be travelled is greater
        
        temperature
        
        rate increases with temperature as particles have more kinetic energy
      - demonstration in agar jelly
        
        uses reaction between potassium permanganate and hydrochloric acid (purple colour disappears)
        
        petri dish containing 2 cm depp of agar jelly prepared
        
        three cubes of different sizes cut out of jelly (0.5 cm, 1cm, 2cm)
        
        dyed purple with potassium permanganate
        
        cubes carefully dropped at same time into hydrochloric acid
        
        time taken for each cube to turn colourless noted
        
        have different volumes and surface areas
    - - water moves across cell membranes by special sort of diffusion called osmosis
      - happens when total concentrations of all dissolved substances inside and outside cell different
        
        water will move across membrane from more dilute solution to more concentrated one
        
        only happen if membrane is permeable to water but not to some other solutes
        
        low water potential to high water potential
        
        water attracted to the solutes
      - experiment
        
        visking tubing is a semi permeable membrane
        
        fill visking tubing sausage with concentrated sucrose solution, attaching to a capillary tube and placing tubing in a beaker of water
        
        level in capillary tube rises as water moves from beaker to inside of visking tubing
    - - happens when need to transport substance against the concentration gradient
      - cell uses energy from respiration to take up substances, like a pump
        
        the 'pumps' are large protein molecules located in cell membrane and driven by breakdown of atp