movement of substances

Nota:

• isosmotic point: the point where two or more substances have the same osmotic pressure and, therefore, will have a flat concentration gradient and osmosis will not take place remember concentration gradient how diluted or concentrated the water is is measured in M

1. definition

   Nota:

   • the net movement of water from a dilute solution (high concentration of water) to a more concentrated solution (low concentration of water) across a partially permiable membrane remember only with water e.g osmosis doesn't happen in orange juice
2. examples
   1. osmosis into potatoes

      Nota:

      • over time, the water will move into the potato or out of the potato depending on the waters isosmotic (the potatoes is constant) pressure through osmosis
   2. turgur pressure in plant cells

      Nota:

      • usually the inside of a plant cell has a more concentrated water solution on the inside than on the outside. this results in water moving into the plant cell. however the cell can't expand due to the rigidity of the cell wall. therefore the inside of the cell has increased pressure keeping the cell rigid. this is called turgur pressure and is important to keep the plant from falling down. similarly if the plant doesn't get enough water the concentration of the solution outside the cell will drop and osmosis will work in the opposite direction making the plant flop.
3. factors effecting osmosis

Nota:

• diffusing-the verb form of diffusion remember concentration gradient

1. definition

   Nota:

   • net movement of particles from a region of high concentration to a low one, moving down the concentration gradient
   1. diffusion on a large scale(not technically diffusion)

      Nota:

      • think of it like air rushing out of a spaceship, particles want to fill the empty space to make it even
2. examples
   1. diffusion in agar blocks

      Nota:

      • over time the acid will defuse into the blocks taking longer with larger blocks. therefore telling us diffusion happens quicker the larger the S.A:V ratio is.
   2. diffusion of oxygen into the blood
3. factors effecting defusion
   1. S.A:V ratio

      Nota:

      • the higher the ratio the faster the rate of diffusion as there is more area for the reaction to take place over
   2. temperature

      Nota:

      • higher temp causes a faster rate of diffusion as the particles have more energy and so move quicker
   3. concentration

      Nota:

      • the higher the concentration the faster the rate of diffusion as the concentration gradient is steeper
   4. same as diffusion
   5. same as osmosis and diffusion

1. definition

   Nota:

   • movement of a substance against the concentration gradient therefore uses energy
2. factors effecting...
3. examples
   1. Root hair cells

      Nota:

      • in plant roots use active transport to absorb mineral ions(such as nitrates) from the soil - even though there are lower concentrations of minerals in the soil than there are within the root hair cell.
   2. Small intestine villi cells

      Nota:

      • use active transport alongside diffusion to maximise the absorption of glucose and other substances, eg minerals.