Question 1

Which of the following best describes the concept of selective permeability in biological membranes?

Accepted Answer

The membrane allows certain molecules to cross more easily than others, depending on their size, charge, and solubility.

Question 2

In a typical mammalian cell, which ion has a higher concentration inside the cell compared to outside?

Accepted Answer

K$$^+$$

Question 3

Which of the following molecules is most permeable through a pure lipid bilayer without a transporter?

Accepted Answer

O$$_2$$

Question 4

Which statement correctly distinguishes between carriers and channels in membrane transport?

Accepted Answer

Carriers undergo conformational changes to move molecules, while channels provide a hydrophilic pathway for ions to flow down their gradient.

Question 5

Which equation describes the rate of simple diffusion across a membrane, according to Fick's law?

Accepted Answer

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

Question 6

A molecule has a partition coefficient (P.C.) of 10. What does this imply about its ability to cross the lipid bilayer?

Accepted Answer

It is highly hydrophobic and will cross the membrane easily.

Question 7

Which of the following best defines osmosis?

Accepted Answer

The movement of water across a semipermeable membrane from low solute concentration to high solute concentration.

Question 8

Calculate the osmolarity of a 0.2 M solution of CaCl$$_2 ($$assume complete dissociation).

Accepted Answer

$$0.6$$ Osm/L

Question 9

A red blood cell is placed in a hypotonic solution. What is the most likely outcome?

Accepted Answer

The cell will swell and may burst as water enters.

Question 10

Which of the following statements about the Na$$^+/K$^+$$ pump is correct?

Accepted Answer

It moves 3 Na$$^+$$ out and 2 K$$^+ in $$per ATP hydrolyzed.

Question 11

Which of the following best describes the driving force for passive transport through a channel?

Accepted Answer

Electrochemical gradient

Question 12

Which of the following is an example of secondary active transport?

Accepted Answer

Na$$^+/$$glucose symporter using the Na$$^+$$ gradient to import glucose against its gradient

Question 13

Which of the following best explains why the GLUT transporter is considered a passive transporter?

Accepted Answer

It facilitates glucose movement down its concentration gradient without energy input.

Question 14

Which of the following is true regarding the difference between symporters and antiporters?

Accepted Answer

Symporters move two solutes in the same direction, antiporters move them in opposite directions.

Question 15

Which of the following is a characteristic of ion channels but not of pumps?

Accepted Answer

They allow rapid, passive movement of ions down their electrochemical gradient.

Question 16

A solution contains 0.1 M glucose, 0.1 M NaCl, and 0.1 M CaCl$$_2. $$What is the total osmolarity of the solution?

Accepted Answer

$$0.6$$ Osm/L

Question 17

Which of the following best describes the Nernst equation and its significance?

Accepted Answer

It determines the equilibrium potential for an ion based on its concentration gradient across the membrane.

Question 18

Which of the following is NOT a type of gated ion channel?

Accepted Answer

Aquaporin channel

Question 19

In the cochlea of the ear, which type of ion channel is primarily responsible for converting mechanical sound vibrations into electrical signals?

Accepted Answer

Mechanical-gated ion channel

Question 20

Which of the following best explains why the Na$$^+/K$^+$$ pump is called a Na$$^+/K$^+$$ ATPase?

Accepted Answer

It uses the energy from ATP hydrolysis to transport Na$$^+$$ and K$$^+$$ ions against their gradients.

Membrane Transport: Key Concepts and Guided Study for Cell Biology

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