$$\phi = \frac{\Delta C \times A \times \beta}{MW \times \Delta X}$$

Question 1

Which of the following statements best explains why biological membranes are considered 'selectively permeable'?

Accepted Answer

They regulate the entry and exit of substances based on hydrophobicity, size, and charge.

Question 2

Which of the following is NOT a major lipid found in biological membranes?

Accepted Answer

Triglycerides

Question 3

How does cholesterol affect the fluidity of a lipid bilayer?

Accepted Answer

It decreases fluidity at high temperatures and increases it at low temperatures.

Question 4

Which property of amphiphilic molecules allows them to self-organize into bilayers?

Accepted Answer

They contain both hydrophilic and hydrophobic regions.

Question 5

Which factor does NOT increase the rate of diffusion across a membrane according to Fick's law?

Accepted Answer

Increasing the molecular weight ($$MW)$$

Question 6

A red blood cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will shrink as water leaves the cell.

Question 7

Which of the following best describes the role of the Na$$^+/K$^+$$ pump in cells?

Accepted Answer

It uses ATP to actively transport Na$$^+$$ out and K$$^+$$ into the cell, maintaining gradients.

Question 8

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses carrier proteins to move molecules down their concentration gradient without energy input.

Question 9

What is the main difference between primary and secondary active transport?

Accepted Answer

Primary active transport uses ATP directly, while secondary uses energy stored in ion gradients.

Question 10

Which equation correctly represents Fick's law of diffusion for the net rate of diffusion ($$\phi$$)?

Accepted Answer

$$\phi = \frac{\Delta C 	imes A 	imes \beta}{MW 	imes \Delta X}$$

Question 11

Which of the following best describes osmosis in biological membranes?

Accepted Answer

Movement of water from low to high solute concentration through a selectively permeable membrane.

Question 12

Which of the following is a function of glycosylated membrane proteins?

Accepted Answer

They act as self-identity markers for cell recognition.

Question 13

Which of the following statements about membrane asymmetry is correct?

Accepted Answer

Asymmetry allows for different intracellular and extracellular environments.

Question 14

Which type of membrane transport is responsible for the uptake of glucose in the gut, coupled to Na$$^+$$ movement?

Accepted Answer

Secondary active transport (symport)

Question 15

Which of the following is NOT a step in vesicle fusion with target membranes?

Accepted Answer

Hydrolysis

Question 16

What is the main function of SNARE proteins in vesicular transport?

Accepted Answer

They mediate specificity and fusion of vesicles with target membranes.

Question 17

Which of the following best describes the movement of ions across a membrane?

Accepted Answer

Ions move passively along their electrochemical gradient.

Question 18

Which of the following is true about vesicle-mediated transport?

Accepted Answer

It requires energy and is used for the transport of large molecules and particles.

Question 19

Which of the following is a real-world example of the use of isotonic saline (0.9% NaCl solution)?

Accepted Answer

As a vehicle for intravenous drug delivery.

Question 20

Which of the following mechanisms is responsible for the excretion of waste products from a cell?

Accepted Answer

Exocytosis

Membrane Structure and Transport: Organic Chemistry Foundations

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