Physiology -Diffusion Quiz

When looking at your data from the effect of concentration on the rate of diffusion lab, what occurred to the rate of diffusion as time elapsed?

the rate of diffusion decreased for all three concentrations of potassium permanganate crystals

In the process of diffusion, when sugar is mixed with water, equilibrium would be reached

when the dissolved sugar molecules are evenly distributed throughout the solution.

If the diffusion rate of one crystal of potassium permanganate within a liquid is 240 mm/hour, predict how far one crystal of potassium permanganate would diffuse within 10 minutes?

40mm

Which of these will affect the rate of diffusion? Concentration gradient Density of media Molecule size Molecular weight All these answers

All theses answers

Which variables affect the rate of diffusion? (Select all that apply.)

Density of Media Size of Molecules Concentration Gradient Membrane Permiability

Heavier (larger) particles move faster than lighter (smaller) particles at the same temperature. True or False

False

What does it mean for a membrane to be semipermeable?

Only certain things can get through.

Equal amounts of methylene blue (319.85 g/mol) and potassium permanganate (158.034 g/mol) dyes were added to identical agar plates and allowed to diffuse. After 24 hours, the halo was measured to see how far the dyes had moved. Based on this information, which dye do you think diffused faster through the agar, and why?

Potassium permanganate had a lower molecular weight, so it was able to diffuse more rapidly spreading farther through the agar in the same time.

Imagine that you have been assigned five substances for which you will observe the rate of diffusion. The only information that you have about your materials is the molecular weight of each substance, listed below: #1: 212 g/molSubstance #2: 1918 g/molSubstance #3: 50 g/molSubstance #4: 4 g/molSubstance #5: 700 g/mol If the substances are allowed to diffuse for one hour, what can you predict about the rate of diffusion?

Substance #4 will diffuse farthest because the molecular weight is least.

Suppose you add solute molecules that are highly concentrated to water and that diffusion of the solute occurs very quickly. What will happen to the distribution of solute after a long time?

The solute concentration will be the same everywhere.

Proteins do not pass through plasma membranes because

They are very large molecules

Diffusion continues to occur until there is an equal concentration of particles on both sides of a semi-permeable membrane. True or False

True

Diffusion is the movement of a molecule from an area of higher concentration to an area of lower concentration.

True

Which of the following factors would increase the rate of diffusion? (Select all that apply)

decreased molecular size larger concentration gradient

In simple diffusion, molecules move from an area of ____ concentration to an area of ____ concentration.

high; low

Which of these will affect the rate of diffusion? Multiple Choiceconcentration gradientdensity of mediamolecule sizemolecular weight

hydrochloric acid (mw = 36 g/mol)

Rate of diffusion is affected by different factors. Of the situations below, predict which one would have the fastest rate of diffusion.

methylene blue (molecular weight = 320 g/mol) that is highly concentrated in a liquid

As molecular weight increases

rate of diffusion decreases

Since the cell membrane allows some molecules to pass through it and will not allow others, it can be described as

selectively permeable.

A membrane allows water through but will not allow any solutes to pass. What type of membrane is this?

semipermeable

Two solutions are made by mixing sugar and enough water to make a 1 liter solution. One contains 10% sugar and the other 20% sugar. Which solution has more solvent?

the 10% sugar solution

When comparing the diffusion rate of a substance at differing concentrations within a liquid (Select all that apply)

the diffusion rate will increase with a higher concentration of the substance.