1Identify solvent and solutes of a solution.
Solvent - Liquid in which a solute dissolves
Solute - The substance that dissolves in a solvent
2Define solvation.
The process by which the positive and negative ions of an ionic solid become surrounded by solvent molecules
3Explain why water is able to dissolve charged and polar molecules.
Polar molecules will dissolve in water because they are hydrophillic and can form hydrogen bonds with water.
4Outline the solvation of hydrophilic and hydrophobic substances.
Hydrophobic molecules can not attract water, so they are insoluble.
Hyrdophobic molecules are attacched to other hydrophobic molecules, so they will clump together when exposed to water.
5Define osmolarity, isotonic, hypotonic and hypertonic.Compare the relative permeability of the plasma membrane to water and solutes.
Osmolarity: a measure of the total concentration of dissolved particles (solutes) in a solution, expressed as the number of osmoles per liter of solution (Osm/L)
Solutions which lower solute concentration are called hypotonic solutions.
Solutions with a higher solute concentration is called hypertonic solution.
Solutions with the same concentration on both sides are called isotonic solutions.
6State the unit for concentration of a solute in a volume of solution.
M (molarity)
7Outline the net movement of water between hypotonic, hypertonic and isotonic solutions.
Hypertonic - Net movement of water out of the cell.
Hypotonic - Net movement of water into the cell.
Isotonic - No net movement of water.
8Compare the relative permeability of the plasma membrane to water and solutes.
The plasma membrane is more permeable to water compared to solutes.
9Define osmosis
Osmosis is described as the net movement of water molecules from a reigon of low solute concentration to high solute concentration.
10Osmosis is what type of transport?
Passive transport - does not require energy
11Explain what happens to cells when placed in isotonic, hypotonic and hypertonic solutions.
Hypotonic - It will gain water, and will continue to do so until it bursts.
Hypertonic - It will loose water and become shrivelled up.
12Explain the change in mass and/or volume of plant tissues placed in either hypotonic or hypertonic solutions.
Mass decreases when placed in hypertonic solutions while mass increases in hypotonic solutions
13Determine the concentration of solutes in a plant tissue given changes in plant tissue mass and/or length when placed in solutions of various tonicities.
plot the percentage change in mass (or length) of the tissue against the external solution concentrations
calculate the percentage change in mass/length: ((Final - Initial) / Initial) x 100%
Hypotonic solutions (lower external solute concentration) will cause water to move into the plant tissue, resulting in an increase in mass and length.
Hypertonic solutions (higher external solute concentration) will cause water to move out of the plant tissue, resulting in a decrease in mass and length.
Isotonic solutions are those with the same water potential as the tissue, leading to no net water movement and thus no change in mass or length
14State the effects of hypertonic and hypotonic solutions on cells without a cell wall.
Without a cell wall, there is no turgor pressure.
This will cause the cell membrane to burst.
15Explain why tissue fluid in multicellular organisms must be isotonic to the cells of the tissue.
so that there is no net movement of water by osmosis. If the tissue fluid is hypotonic, water enters the cells, causing them to swell and burst; if it's hypertonic, water leaves the cells, causing them to shrink (crenation), both of which are harmful to the cells and the organism.
16Outline the role of the contractile vacuole in freshwater unicellular organisms.
Excess water will be continuously collected in the contractile vacuole and pumped out of the organism to maintain the osmotic concentration of the cytoplasm
17Describe the strength and permeability of a cell wall.
- Cell wall is inelastic, which prevents cell from bursting.
- This is important for plants as when the cells are turgid and firm, it creates support for the plant.
- Helps plant stand upright to catch sunlight
- if plants do not receive enough water the cells cannot remain rigid and firm (turgid) and the plant wilts
18Explain the effects of hypertonic and hypotonic solutions on cells with a cell wall with specific reference to turgor pressure and plasmolysis.
Hypotonic solution:
As water enters vacuole of plant cell, the volume increases.
This puts pressure against the wall, called turgor pressure.
Hypertonic solution:
Water will leave the plant, which causes the volume to decrease.
The protoplast will shrink and pull away from the cell wall.
This is knwon as plasmolysis, where the plant cell becomes flaccid.
19State the effects of isotonic, hypertonic and hypotonic solutions on human cells.
Hypotonic:
- Water rushes into cells causing them to burst.
- Lead to a decrease in oxygen carrying capacity of blood.
Hypertonic:
- Water would rush out of the cell, causing the cell to shrivel.
- Increases risk of blood clotes as shrivelled blood cells cannot move freely through capillaries.
20Outline the use of “normal saline” in medical procedures.
patients may require an intravenous (IV) drip to treat dehydration or to deliver medicine directly into the bloodstream
A 0.9% sterile saltwater solution.
Designed to be isotonic in relation to blood plasma.
If the solution was hypotonic then there would be a net movement of water into red blood cells causing them to burst
This would result in a decrease in the oxygen carrying capacity of blood
hypertonic IV solution would result in a net movement of water out of the red blood cells causing them to shrivel and become crenated
This would increase the risk of blood clots forming as these red blood cells cannot move freely through capillaries
preparation of donated human organs for transplant surgery
These organs must be kept in an isotonic saline solution to prevent damage to the cells due to the net movement of water by osmosis