Diffusion Lab Notes

Reviewing the State Lab

What can we conclude from this lab exercise?

• The cell membrane regulates what goes in and out of the cell

• Small or simple molecules pass easily through the cell membrane

• The diffusion of water into and out of the cell is called osmosis

• If too much water leaves the cell, it shrinks

How do we know this?

• Created cell to model osmosis and cell turned blue black because iodine went into the cell

• Cell watery environment had glucose in it-turned milky orange in presence of Benedicts

• Onion cell shrunk in salt water and went back to original size after rinsed

Other Facts

• Indicator- a chemical that reacts with another chemical and makes the color change indicating its presence

• Lugol’s-indicates the presence of starch, turns blue black

• Benedict’s Solution- indicates the presence of glucose-turns milky orange when heated

What kind of molecules can pass through membrane easily?

• Simple ones-ex: glucose• Water

• Large complex molecules do not- ex: Starch

What determines whether salt solution or water enters the cell?

• The concentration of water must be greater either inside or outside for water to leave or enter

• Water will move from high to low

Osmosis

Concentration inside

Concentration outside

Water will Cell will

High Low Leave Shrink-Hypertonic

Low High Enter Grow and may explode-hypotonic

Equal to outside Equal to inside Stay same Maintain balance orEquilibrium-isotonic