not mock (osmosis)

• define osmosis

  the diffusion of water molecules across a partially permeable membrane down a water potential gradient until equilibrium is reached
• what is the water potential of water

  0
• what is the water potential of other solutions

  negative
• what are hypotonic solutions (animals)

  solution with a higher water potential than the cell, the net movement of water is into the cell. The cell bursts
• what are isotonic solutions (animals)

  solutions with the same water potential as the cell, water moves into and out of the cell in equal amounts. The cell stays the same
• what are hypertonic solutions (animals)

  solutions with a lower water potential than the cell, the net movement of water is out of the cell. The cell shrinks
• what happens in hypotonic solutions in plants

  the vacuole swells. The vacuole and the cytoplasm push against the cell wall. The cell wall becomes turgid (swollen)
• what happens in hypertonic solutions in plants

  the cell becomes flaccid (shrinks). The cytoplasm and the membrane pull away from the cell wall --> plasmolysis
• describe a method to find the effects of osmosis on plant tissue

  1) prepare sucrose solutions of 0M, 0.2M, 0.4M... to 1M

  2) use a cork borer to cut the potatoes into equal sized pieces (about 1cm in diameter)

  3) divide the chips into groups of 3 and use a mass balance to weigh the initial mass of each group

  4) place one group in each solution for about 20 mins

  5) remove the chips and pat gently with a paper towel to remove excess water

  6) weigh each group to find final mass

  7) calculate the % change in mass
• how can you find the effects of osmosis on animal tissue

  use the same method on eggs with their shells dissolved to get the partially permeable membrane