Movements Through Membranes

Define diffusion

Passive, random movement of molecules with their concentration gradient

Define osmosis

Passive movement of water molecules through a porous membrane with their concentration gradient (from hypotonic region to hypertonic region)

Define filtration

Movement of molecules through a porous membrane using hydrostatic forces, size of molecules (not concentration different) matters, bulk (not random) flow

Why is it possible to demonstrate diffusion, osmosis, and filtration in experiments that do not include living tissue?

Passive, cellular energy in the form of ATP is not required

Respiratory gasses and ions move by

Diffusion

Glucose moves into cells by

Facilitated diffusion

KMnO4 experiment

KMnO4 molecules passively moved with their concentration gradient (high to low)

Different permeability, what would make membranes in your body have different permeability?

The type and distribution of ion channels present

Percent transmittance is the percent of light that passes through the solution, which…

When blood cells are placed in a relatively hypotonic solution, they take on water from the surroundings and swell. The enlarged cells block less light, increasing transmittance. When blood cells are placed in a hypertonic solution, they lose volume to the surroundings and shrink. The shrunken cells block more light, decreasing transmittance. Cells placed in a relatively isotonic solution exchange water with their surroundings but do not swell or shrink.

Was the solution in the beakers hypertonic, hypotonic, or isotonic to the solution in the dialysis bags?

Hypotonic, water always moves with its concentration gradient from the relatively hypotonic region toward the relatively hypertonic region

Was sugar present in the filtrate?

Yes, it was positive because it turned green, yellow, orange, red

Starch: Negative

Yellow/orange

Starch: Positive

Black, dark green, purple

Sugar: Negative

Blue

Sugar: Positive

Yellow, green, orange, red

Experimental design: What are features of good experimental design

Only examining one variable at a time, repetition, using positive and negative controls