1.1 Life Processes - Movement of Substances In and Out of Cells

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GCSE Biology Mind Map on 1.1 Life Processes - Movement of Substances In and Out of Cells, created by sachakoeppen on 05/26/2015.

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1.1 Life Processes - Movement of Substances In and Out of Cells
  1. Chemical reactions enter and leave the cell in 3 ways
    1. Diffusion
      1. Active Transport
        1. Osmosis
        2. Diffusion
          1. Diffusion happens when a substance is more concentrated in one place than another (when you spray a can of deodorant)
            1. This difference in concentration is called a concentration gradient
              1. The particles move from an area of high concentration to an area of low concentration
            2. Factors affecting rate of diffusion
              1. Surface area to volume ratio
                1. If the volume of two cells is similar, the one with the biggest surface area will have a larger surface area to volume ratio
                  1. Therefore it will increase the rate of diffusion
                2. Temperature
                  1. At a higher temp the particles have more kinetic energy and are moving around faster.
                    1. Therefore in a given time more diffusion will occur
                  2. Concentration Gradient
                    1. When there is a big difference between the number of particles in one place and another, diffusion will happen much faster than if they are already quite spread out
                3. Active Transport
                  1. Sometimes a cell needs to take in a substance against a concentration gradient
                    1. This requires energy released from respiration, this is called active transport
                      1. Particles move from an area of low concentration to an area of high concentration
                      2. Occurs in the roots of plants to move minerals into them against the concentration gradient and also in the small intestine of animals
                      3. Osmosis
                        1. Water molecules move from an area of high concentration to an area of low concentration through the partially permeable membrane
                          1. Partially permeable membrane has tiny holes (pores) through which very small molecules (including water) can pass, but not larger molecules (such as sugar and proteins)
                        2. Experiment to investigate surface area to volume ratio
                          1. 3 different sized cubes of agar are prepared which contain the indicator phenolphthalein.
                            1. These are placed in hydrochloric acid which will diffuse into the cubes
                              1. As it diffuses it will turn the indicator colourless
                                1. As the size of the cube increases the surface area to volume decreases
                                  1. The smallest cube will be colourless, the middle cube will have a but of pink in the middle and the largest cube will still be pink
                                    1. If these were real cells then the bigger cell wouldn't have received what it needs to all parts of the cell
                                      1. Therefore, it would need a bigger surface in order to rely on diffusion
                          2. Surface Area
                            1. As the rate of diffusion relies on the surface area, the parts of the organisms that rely on diffusion tend to have a large surface area
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