Question 1

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic bilayer of phospholipids with proteins and carbohydrates embedded and moving laterally

Question 2

Why do fish living in extremely cold environments have membranes with a high proportion of unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids prevent tight packing of phospholipids, maintaining membrane fluidity at low temperatures

Question 3

Which of the following molecules is most likely to diffuse freely across a lipid bilayer without the aid of a transport protein?

Accepted Answer

Oxygen (O₂)

Question 4

A plant cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

It will swell until it becomes turgid, but will not burst due to the cell wall

Question 5

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral proteins penetrate the hydrophobic core of the lipid bilayer

Question 6

What is the main function of cholesterol in animal cell membranes?

Accepted Answer

To buffer membrane fluidity against temperature changes

Question 7

Which process requires energy input in the form of ATP?

Accepted Answer

Active transport

Question 8

A red blood cell placed in a hypertonic solution will:

Accepted Answer

Lose water and shrink

Question 9

Which of the following best explains why aquaporins allow water but not hydronium ions (H₃O⁺) to pass through?

Accepted Answer

Aquaporins are specific for the size and polarity of water molecules, and the channel excludes ions based on their charge and hydration shell

Question 10

Which of the following is an example of bulk transport?

Accepted Answer

Exocytosis

Question 11

The sodium-potassium pump is an example of:

Accepted Answer

Active transport

Question 12

Which of the following best describes selective permeability?

Accepted Answer

The membrane allows some substances to cross more easily than others

Question 13

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

There will be no net movement of water

Question 14

Which of the following is true about the movement of phospholipids in the membrane?

Accepted Answer

They move laterally within the layer very frequently

Question 15

Which of the following best explains why glucose crosses the plasma membrane slowly without a transport protein?

Accepted Answer

Glucose is a large polar molecule

Question 16

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Cell-cell recognition

Question 17

Which of the following best describes cotransport?

Accepted Answer

The coupling of the downhill diffusion of one substance to the uphill transport of another against its concentration gradient

Question 18

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Uptake of cholesterol by animal cells via LDL receptors

Question 19

Which of the following best explains why the cytoplasmic side of the plasma membrane is negative relative to the extracellular side?

Accepted Answer

There is an unequal distribution of anions and cations across the membrane

Question 20

Which of the following equations best represents the energy change associated with ATP hydrolysis used in active transport?

Accepted Answer

$$ \mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy} $$

Membrane Structure and Function: Study Guide for General Biology

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