Lab #3 Review - Osmosis

Lab #3 Review Terms

Osmosis

Passive process (no ATP spent), water molecules move from one crowded area to an area where are more spread apart

Concentration Gradient

When two areas have different concentrations of dissolved substances

Tonicity

Ability of a solution to cause a cell to gain or lose water

Osmolarity

Total solute concentration, tonicity is based on this

Hypertonic

Solution has a relatively higher solute concentration

Hypotonic

Solution has a lower solute concentration

Isotonic

Solutions of equal solute concentration

Water movement

Water moves out of hypotonic solution to a hypertonic solution

Plasmolysis

Process involving a plant cell losing water content and therefore contracting and shrinking its cytoplasm and plasma membrane away from the inside of its cell wall

Turgid

a cell that is swollen and firm due to being filled with water

Osmosis effect on Plant Cells

Central Vacuoles

Found in plant cells, stores water and dissolved sugars

Salt Concentration

Influences plant cell osmosis

Diameter of Central vacuole OR diameter of plasma membrane

Internal structure to measure to indicate changes that occur within the cell under varying salt concentrations

Elodea

Cells tightly packed together like bricks in a wall, rectangular shaped cells, not free swimming (non-motile), green color

Euglena

Single, isolated, fully motile cells move through aquatic environment with flagellum. Protists, greenish-blue. No cell wall, flexible pellicle under plasma membrane.

If a cell has a smaller SA & Volume, it is able to supply the greatest proportion of its volume with nutrients. Larger cell would be a risk of starving.

Surface Area/Volume & Feeding Efficiency

Increase in size, decrease % fed

as cells get larger, their Volume increase at a faster rate than do their surface area, thus feed and remove waste less efficiently

As cell increases in size, how does the portion of the cell that receives nutrients change?

Sa/V ratios need to be large enough to sustain high transport/exchange of efficiencies

As cells grow larger, they can either… 1. divide into 2 smaller cells. 2. grow thin cellular extensions that maximize surface area

Why is cell size limited?