Q: Order the following substances from most permeable to least permeable across a typical phospholipid bilayer: O\textsubscript{2}, H\textsubscript{2}O, glucose, Na\textsuperscript{+}.

O\textsubscript{2} \u003e H\textsubscript{2}O \u003e glucose \u003e Na\textsuperscript{+}

Question 1

Which property of phospholipids is primarily responsible for the spontaneous formation of lipid bilayers in water?

Accepted Answer

Their amphipathic nature, with both hydrophilic and hydrophobic regions

Question 2

A cell membrane is described as a 'selective barrier.' What does this mean in terms of molecular transport?

Accepted Answer

It allows entry of needed materials and keeps out damaging substances

Question 3

Which of the following substances would cross a phospholipid bilayer most rapidly?

Accepted Answer

O	extsubscript{2} (oxygen)

Question 4

What effect does increasing the proportion of unsaturated fatty acids in membrane phospholipids have on membrane fluidity?

Accepted Answer

It increases membrane fluidity

Question 5

Which part of a phospholipid molecule is in direct contact with water in a bilayer?

Accepted Answer

Hydrophilic head

Question 6

Order the following substances from most permeable to least permeable across a typical phospholipid bilayer: O	extsubscript{2}, H	extsubscript{2}O, glucose, Na	extsuperscript{+}.

Accepted Answer

O	extsubscript{2} \u003e H	extsubscript{2}O \u003e glucose \u003e Na	extsuperscript{+}

Question 7

What is the main effect of adding cholesterol to a cell membrane?

Accepted Answer

It decreases membrane permeability by increasing packing density

Question 8

A red blood cell is placed in a beaker of pure, distilled water. What will happen to the cell?

Accepted Answer

The cell will swell and likely burst as water rushes in

Question 9

Which of the following best describes osmosis?

Accepted Answer

Movement of water from low solute concentration to high solute concentration across a selectively permeable membrane

Question 10

How does temperature affect membrane fluidity and permeability?

Accepted Answer

As temperature decreases, membrane fluidity and permeability decrease

Question 11

A fish living in cold Arctic waters is likely to have cell membranes with which characteristics compared to a tropical fish?

Accepted Answer

More unsaturated fatty acids and lower cholesterol

Question 12

Which of the following foods is primarily made of unsaturated fatty acids?

Accepted Answer

Vegetable oil

Question 13

What structural feature of unsaturated fatty acids increases membrane permeability?

Accepted Answer

Double bonds causing 'kinks' in the hydrocarbon chain

Question 14

Which equation best describes the net movement of water during osmosis?

Accepted Answer

$$J = -P (C_1$ - C_2$)$$, where $$J is $$the flux, $$P is $$permeability, and $$C_1$$ and $$C_2$$ are concentrations on either side of the membrane

Question 15

Which of the following statements about passive transport is correct?

Accepted Answer

It occurs when substances diffuse across membranes without an outside energy source

Question 16

What is the primary role of phospholipids in cells?

Accepted Answer

To form cell membranes

Question 17

Which factor would most likely decrease the permeability of a cell membrane?

Accepted Answer

Increasing the length of hydrocarbon tails

Question 18

Which of the following best explains why highly saturated lipids are solid at room temperature?

Accepted Answer

Their hydrocarbon tails pack tightly due to strong hydrophobic interactions

Question 19

What would happen to a vesicle containing a lower concentration of solute than its surrounding solution?

Accepted Answer

Water would flow out of the vesicle, causing it to shrink

Question 20

Which of the following is NOT a factor that influences membrane permeability?

Accepted Answer

Presence of ribosomes

Membrane Structure and Properties: Study Notes for General Biology

Study Guide - Practice Questions

Study Guide - Flashcards