Chapter 6.3.1 (Exam 1) Passive Transport

Question 1

Plasma membranes have selective permeability. What are the two types of transport across a plasma membrane?

Answer 1

Passive transport: no energy required

Active transport: energy required

Question 2

What is diffusion?

Answer 2

The process of random movement toward equilibrium

The net movement from regions of greater concentration to regions of lesser concentration

Question 3

What does diffusion rate depend on?

Answer 3

STACD

Size and mass of the molecules or ions
Temperature of the solution
Area and distance diffusion occurs
Concentration gradient
Density of the solution

Question 4

What is simple diffusion?

Answer 4

Small molecules that are lipid-soluble pass through the lipid bilayer

A small amount of water can also pass through via simple diffusion

Question 5

For which molecules does simple diffusion not work? Why?

Answer 5

Electrically charged and polar molecules can’t pass through easily

The inside portion of the bilayer is nonpolar (repels charged molecules)

Question 6

What is osmosis?

Answer 6

Diffusion of water

Question 7

What does the direction of osmosis depend on?

Answer 7

Water travels from low solute concentration to high solute concentration

Water travels towards the hypertonic solution to dilute it

Question 8

What are the 3 types of solutions based on solute concentrations?

Answer 8

Isotonic: equal solute concentrations

Hypertonic: higher solute concentration

Hypotonic: lower solute concentration

Question 9

What solution (tonicity) is needed outside to maintain cell shape?

Answer 9

Isotonic

Question 10

What happens if an animal cell is placed into a hypotonic solution? A hypertonic solution?

Answer 10

Water always goes to higher concentration, so the cell placed in a hypotonic solution will absorb water until it bursts or the concentration is equalized

For the other cell, water will exit the cell to dilute the external concentration which is higher

Question 11

Why don’t plant cells burst when placed into a hypotonic solution?

Answer 11

Their cell wall prevents too much water from entering the cell

Internal pressure called turgor pressure builds up until the amount of water exiting and entering are in equilibrium