3.2 Movement Of Substances Across The Plasma Membrane In Eve

3.2 Movement of Substances across the Plasma Membrane in Everyday Life

Types of solution

Three types of solution: 3. Hypotonic 4. Hypertonic 5. Isotonic

Hypotonic solution – the concentration of solute outside a cell is lower than the concentration of solute inside of the cell (Hypo – lower) Hypertonic solution – the concentration of solute outside the cell is higher than the concentration of solute inside of the cell (Hyper – higher) Isotonic solution – the concentration of solute outside the cell is equal with the concentration of solute inside of the cell (Iso – equal)

Effect of hypotonic, hypertonic and isotonic solution on animal cells

Red blood cell is put in a hypotonic solution – water from the surrounding enters the cell by osmosis causing it to swell up and burst (haemolysis – the bursting of red blood cell) Red blood cell is put in a hypertonic solution – water from inside the cell move out of the cell by osmosis causing the cell to shrink (crenation – the shrinking of the cell) Red blood cell is put in an isotonic solution – no change to the cell because the amount of water entering and leaving the cell is the same

Summarisation

Effect of hypotonic, hypertonic and isotonic solution on plant cells

A plant cell place in a hypotonic solution – cell swell and become turgid but does not burst because the cell wall resist the pressure (turgor pressure) stop the cell from expanding, the cell wall stretch but does not break A plant cell place in a hypertonic solution – cell shrink and flaccid (plasmolysis – the shrinking of the cell, opposite process deplasmolysis ) A cell place in an isotonic solution – no change because the amount of water entering and leaving the cell is equal

Summarisation

The Effects and Application of Osmosis in Everyday Life

Group discussion Discuss how osmosis occur in 3. Wilting plant 4. Food preservation

Cells in living organism have to maintain their osmotic balance so that they will not burst or crenate (interstitial fluid has the same concentration as the cytoplasmic fluid) Wilting plant – happens when too much fertilizer is added to the soil or water shortage in soil. Food preservation – adding salt or sugar to the preserve food will cause hypertonic environment to the decomposers and they will die due to losing water to the surrounding solution

3.3 Appreciating the Movement of Substances across the Plasma Membrane

2. 3. 4. 5.

Movement of substances across the plasma membrane is very important because: To maintain a suitable pH and ionic concentration inside the cell for enzymatic activities To obtain food supplies for energy and raw materials To remove toxic substances or secrete useful substances To generate ionic gradients essential for muscular and nervous activities

Test Yourself 1. What happen if an animal cells is put in a hypotonic solution? 2. Why plant cells does not burst when these cells is put in a hypertonic solution? 3. Why is the movement of substances across the plasma membrane is important for the survival of living organisms?

Thing that we’ve learned today: The meaning of hypotonic, hypertonic and isotonic solutions. Effect of hypotonic, hypertonic and isotonic solution on animal cells. Effect of hypotonic, hypertonic and isotonic solution on plant cells. The Effects and Application of Osmosis in Everyday Life Appreciating the Movement of Substances across the Plasma Membrane