Question 1

Which component of the plasma membrane is primarily responsible for its fluidity and ability to self-heal after minor damage?

Accepted Answer

Phospholipids

Question 2

According to the fluid mosaic model, which statement best describes the arrangement of proteins in the plasma membrane?

Accepted Answer

Proteins are embedded in a fluid bilayer of phospholipids, forming a dynamic mosaic.

Question 3

Which property of phospholipids allows them to form bilayers in aqueous environments?

Accepted Answer

Their amphipathic nature, with hydrophilic heads and hydrophobic tails

Question 4

A cell membrane is exposed to cold temperatures. Which modification would help maintain membrane fluidity under these conditions?

Accepted Answer

Increasing the proportion of unsaturated fatty acids

Question 5

Which of the following best explains why cholesterol acts as a 'temperature buffer' in animal cell membranes?

Accepted Answer

Cholesterol prevents the membrane from becoming too fluid at high temperatures and too solid at low temperatures.

Question 6

Which type of membrane protein is most likely to be involved in cell recognition and immune response?

Accepted Answer

Glycoproteins

Question 7

A freshwater protist living in a hypotonic environment uses a contractile vacuole to maintain water balance. What process is this an example of?

Accepted Answer

Osmoregulation

Question 8

Which equation best represents the net movement of water across a selectively permeable membrane due to osmosis?

Accepted Answer

$$J = -L_p (\Delta P - \sigma \Delta \pi)$$

Question 9

A red blood cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will lose water and shrink (crenate).

Question 10

Which type of transport requires energy input from the cell and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 11

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Active transport

Question 12

Which equation describes the energy required to move an ion across a membrane, considering both concentration and electrical gradients?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[C]_2}{[C]_1} \right) + zF\Delta \psi$$

Question 13

Which process involves the fusion of vesicles with the plasma membrane to release their contents outside the cell?

Accepted Answer

Exocytosis

Question 14

Which type of endocytosis is most specific for the uptake of certain molecules, such as cholesterol via LDL receptors?

Accepted Answer

Receptor-mediated endocytosis

Question 15

Which of the following molecules can most easily cross the plasma membrane without the aid of transport proteins?

Accepted Answer

Oxygen ($$O_2)$$

Question 16

A plant cell placed in a hypotonic solution will become:

Accepted Answer

Turgid

Question 17

Which type of membrane protein is most likely to function as an enzyme catalyzing reactions at the membrane surface?

Accepted Answer

Enzymatic protein

Question 18

Which process best describes the movement of glucose into a cell via a sodium-glucose cotransporter?

Accepted Answer

Cotransport (secondary active transport)

Question 19

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Energy storage

Question 20

Which scenario best illustrates facilitated diffusion?

Accepted Answer

Glucose moving into a cell via a specific carrier protein down its concentration gradient

Membrane Structure and Function: Study Notes (Chapter 7)

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