Q: A cell is observed to have a high concentration of Na\textsuperscript{+} outside and K\textsuperscript{+} inside. Which membrane protein is responsible for maintaining this gradient?

Na\textsuperscript{+}/K\textsuperscript{+}-ATPase

Question 1

Which component of the fluid mosaic model is primarily responsible for the selective permeability of cellular membranes?

Accepted Answer

Phospholipid bilayer

Question 2

A red blood cell is placed in a hypotonic solution. What will happen to the cell, and which principle explains this phenomenon?

Accepted Answer

It will swell and possibly burst due to osmosis

Question 3

Which type of membrane protein is covalently attached to fatty acids and is embedded within the membrane but does not span it?

Accepted Answer

Lipid-anchored protein

Question 4

Which equation best describes the net movement of solute during simple diffusion across a membrane?

Accepted Answer

$J = -D \frac{dC}{dx}$

Question 5

Which of the following is NOT a function of cellular membranes as listed in Table 5.1?

Accepted Answer

Synthesis of DNA

Question 6

A mutation causes a cell to lack cadherin proteins. Which cellular process would be most directly affected?

Accepted Answer

Cell recognition and adhesion

Question 7

Which type of junction is responsible for preventing the passage of substances between adjacent animal cells, such as in the blood-brain barrier?

Accepted Answer

Tight junctions

Question 8

Which process requires energy input and moves substances against their concentration gradient?

Accepted Answer

Active transport

Question 9

Which of the following best describes the role of integrins in cellular membranes?

Accepted Answer

They connect cells to the extracellular matrix

Question 10

A patient has a genetic defect in aquaporin channels. Which physiological process would be most directly impaired?

Accepted Answer

Facilitated diffusion of water

Question 11

Which equation represents the Michaelis-Menten kinetics for a carrier protein-mediated transport?

Accepted Answer

$v = \frac{V_{max}[S]}{K_m + [S]}$

Question 12

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

Accepted Answer

Uptake of low-density lipoprotein (LDL) by cells

Question 13

Which of the following statements about the extracellular matrix (ECM) is correct?

Accepted Answer

Collagen provides tensile strength to the ECM

Question 14

Which type of active transport directly uses ATP to move ions across the membrane?

Accepted Answer

Primary active transport

Question 15

Which of the following best explains why ions such as Na	extsuperscript{+} and K	extsuperscript{+} cannot freely diffuse across the lipid bilayer?

Accepted Answer

They are charged and the hydrophobic core of the bilayer repels them

Question 16

Which of the following is a function of gap junctions in animal cells?

Accepted Answer

Allowing direct communication and passage of ions and small molecules

Question 17

A cell is observed to have a high concentration of Na	extsuperscript{+} outside and K	extsuperscript{+} inside. Which membrane protein is responsible for maintaining this gradient?

Accepted Answer

Na	extsuperscript{+}/K	extsuperscript{+}-ATPase

Question 18

Which process is used by immune cells such as macrophages to engulf and destroy pathogens?

Accepted Answer

Phagocytosis

Question 19

Which of the following best describes the role of carbohydrates on the external side of the plasma membrane?

Accepted Answer

They are involved in cell recognition and adhesion

Question 20

Which plant cell structure is analogous to gap junctions in animal cells, allowing direct cytoplasmic exchange between adjacent cells?

Accepted Answer

Plasmodesmata

Cellular Membranes: Structure, Composition, and Functions

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