J_x = P_xA (C₁-C₂)

J_x = Rate of diffusion

P_x = Permeability coefficient (cm/sec)

A = Surface area (cm²)

C = concentration (mmol/L OR mg/ml)

NOTE: 1 ml = 1 cm³

What happens to rate of diffusion if;

1. ↑A 

2. ↑C1 

3. ↑C2 

4. ↑w 

1. = ↑J_x

2. = ↑J_x

3.=↓J_x

4. = ↓J_x

(w = membrane thickness, lowers P_x)

Facilitated diffusion,

primary active transport,

secondary active transport

Which of the following types of membrane transport directly use ATP?

diffusion

pores

channels

facilitated diffusion

primary active transporter

secondary active transporter

Which of the following types of membrane transport does not require a direct or indirect energy source to move molecules across a membrane?

The rate of diffusion of a particle across a membrane will increase with which of the following changes?

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Identify #1-5

The movement of glucose through a Na+/glucose cotransporter is an example of what type of membrane transport?

                A.  Primary active transport

                B.  Secondary active transport

                C.  Simple diffusion

                D.  Facilitated diffusion

                E.  Vesicular transport

Which properties are characteristic of ion channels?

                A.  They are made of lipids

                B.  They exist on one side of the plasma   membrane, usually the intracellular side

                C.  They can open and close depending on the presence of any of three types of ‘gates’

                D.  They permit movement of ions against their concentration gradients

                E.  They mediate primary active transport

The permeability of a solute in a lipid bilayer will be increased by an increase in which of the following?

                A.  Molecular radies of the solute

                B.  Particle coefficient of the solute

                C.  Thickness of the bilayer

                D.  Ionic charge of the molecule

In considering diffusion of ions through an ion channel, which driving force(s) must be considered?

                A.  Only the ion concentration gradient

                B.  Only the electrical gradient

                C.  Osmosis alone

                D.  The ion concentration AND electrical gradients

                E.  Osmosis AND the ion concentration gradient

                F.  Osmosis AND the electrical gradient

Which statement is incorrect?

                A.  Diffusion of a solute through a membrane is considerably quicker than diffusion of the same solute through a water layer of equal       thickness.

                B.  A single ion, such as K+, can diffuse through more than one type of channel.

                C.  Lipid-soluble solutes diffuse more readily through the phospholipid bilayer of a plasma membrane than do water-soluble ones.

                D.  The rate of facilitated diffusion of a solute is limited by the number of transporters in the membrane at any given time.

.  The rate of diffusion of a particle across a membrane will increase if which of the following occurs?

                A.  The area of the membrane decreases

                B.  The thickness of the membrane increases

                C.  The size of the particle increases

                D.  The concentration gradient of the particle decreases

                E.  The lipid solubility of the particle increases

.  In which of the following transport processes is the substance moving down its electrochemical gradient?

                A.  Sodium out of a nerve cell by the Na/K ATPase

                B.  Calcium into the sarcoplasmic reticulum by the Ca2+ ATPase

                C.  Hydrogen into the lumen of the distal nephron by the H+ ATPase pump

                D.  Glucose into adipose tissue through a facilitated diffusion glucose transporter

                E.  Potassium into striated muscle cells by the Na/K ATPase

Which of the following characteristics is shared by simple and facilitated diffusion of glucose?

                A.  Occurs down an electrochemical gradient

                B.  Is saturable

                C.  Requires metabolic energy

                D.  Is inhibited by the presence of galactose

                E.  Requires a Na+ gradient

Which of the following transport processes is involved if transport from the intestinal lumen into a small intestinal cell is inhibited by abolishing the usual Na+ gradient across the cell membrane?

                A.  Simple diffusion

                B.  Facilitated diffusion

                C.  Primary active transport

                D.  Secondary active cotransport