Question 1

Which of the following molecules will diffuse most rapidly across the plasma membrane of a muscle cell?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 2

A muscle cell needs to expel carbon dioxide ($$\mathrm{CO_2$}) $$after cellular respiration. By which process does $$\mathrm{CO_2$}$$ most likely exit the cell?

Accepted Answer

Simple diffusion through the lipid bilayer

Question 3

Which statement best explains why ions such as $$\mathrm{Na^+}$$ and $$\mathrm{K^+}$$ require transport proteins to cross the plasma membrane?

Accepted Answer

Ions are hydrophilic and are repelled by the hydrophobic interior of the membrane.

Question 4

A patient is diagnosed with a genetic mutation that prevents the formation of aquaporins in kidney cells. What is the most likely physiological consequence?

Accepted Answer

Decreased rate of water reabsorption from urine

Question 5

Which of the following best describes the specificity of carrier proteins in the plasma membrane?

Accepted Answer

Carrier proteins are highly selective and only transport specific molecules.

Question 6

A muscle cell regulates its internal concentration of $$\mathrm{K^+} by $$moving it across the membrane. Which property of the plasma membrane enables this regulation?

Accepted Answer

The membrane is selectively permeable, allowing controlled movement of ions.

Question 7

Which of the following is TRUE regarding the movement of glucose and fructose into liver cells?

Accepted Answer

Glucose is transported by a specific protein, but fructose is not, despite being a structural isomer.

Question 8

Which of the following statements about channel proteins is correct?

Accepted Answer

Channel proteins create hydrophilic tunnels that allow specific molecules or ions to pass through.

Question 9

A scientist observes that water moves rapidly across a cell membrane. Which structure is most likely responsible for this observation?

Accepted Answer

Aquaporins forming water channels

Question 10

Which of the following molecules would have the most difficulty crossing the plasma membrane without assistance?

Accepted Answer

Sodium ion ($$\mathrm{Na^+})$$

Question 11

Which process allows amino acids to enter muscle cells through the plasma membrane?

Accepted Answer

Facilitated diffusion via transport proteins

Question 12

What is the main function of membrane proteins in the context of selective permeability?

Accepted Answer

They assist in the transport of ions and polar molecules and regulate entry and exit.

Question 13

Which of the following is a property of aquaporins?

Accepted Answer

They are channel proteins that increase the rate of water transport.

Question 14

A mutation causes a muscle cell to lack functional carrier proteins for $$\mathrm{Na^+}. $$What is the most likely result?

Accepted Answer

Impaired regulation of $$\mathrm{Na^+}$$ concentration inside the cell

Question 15

Which of the following statements best describes the role of the lipid bilayer in membrane permeability?

Accepted Answer

It allows hydrophobic molecules to dissolve and pass through quickly.

Question 16

Which of the following is TRUE about the movement of small molecules and ions across the plasma membrane?

Accepted Answer

Movement occurs in both directions, into and out of the cell.

Question 17

Why do sugars such as glucose require transport proteins to enter muscle cells?

Accepted Answer

They are polar and cannot cross the hydrophobic interior of the membrane unaided.

Question 18

Which of the following statements about the structure of aquaporins is correct?

Accepted Answer

Each aquaporin is composed of four polypeptide subunits, each forming a channel for water.

Question 19

Which of the following best describes the difference between channel proteins and carrier proteins?

Accepted Answer

Channel proteins form hydrophilic channels, while carrier proteins bind to specific molecules and change shape to transport them.

Membrane Structure and Function Pt. 2

Guida di studio - Domande di pratica

Study guide - Flashcard