Question 1

Which of the following best describes the amphipathic nature of phospholipids in biological membranes?

Accepted Answer

They have a hydrophilic head and two hydrophobic tails.

Question 2

A deficiency in which type of membrane lipid is associated with West syndrome, a form of epilepsy?

Accepted Answer

Gangliosides

Question 3

Which interaction is primarily responsible for the self-assembly of phospholipid bilayers in aqueous environments?

Accepted Answer

Hydrophobic force

Question 4

How does cholesterol affect the fluidity of animal cell membranes at physiological temperature ($$37\ ^\circ \mathrm{C}$$)?

Accepted Answer

It decreases membrane fluidity by making the membrane more rigid.

Question 5

Which of the following membrane lipids is characterized by a backbone of amino alcohol sphingosine?

Accepted Answer

Sphingolipids

Question 6

A patient presents with a neurological disorder linked to abnormal membrane lipid composition. Which class of lipids is most likely involved, given their abundance in the brain and role in cell signaling?

Accepted Answer

Gangliosides

Question 7

Which property of fatty acid chains in phospholipids increases membrane fluidity?

Accepted Answer

Short, unsaturated hydrocarbon chains

Question 8

What is the main function of integral membrane proteins?

Accepted Answer

They catalyze reactions, anchor the membrane, and act as receptors.

Question 9

Which of the following statements about membrane carbohydrates is correct?

Accepted Answer

They always face the extracellular side and mediate cell-environment interactions.

Question 10

A drug must cross the cell membrane to reach its target inside the cell. Which property would most enhance its ability to diffuse directly through the lipid bilayer?

Accepted Answer

Nonpolar and small molecular size

Question 11

Which process allows phospholipids to move from one leaflet of the bilayer to the other, and what enzyme facilitates this?

Accepted Answer

Transverse diffusion (flip-flop); flippase

Question 12

Which of the following best explains why phospholipid bilayers spontaneously form sealed compartments in water?

Accepted Answer

It is energetically favorable because hydrophobic tails are shielded from water.

Question 13

Which membrane lipid is most likely to be found in higher concentration in nerve cells and is important for myelin sheath formation?

Accepted Answer

Sphingomyelin

Question 14

If a cell membrane is composed mainly of saturated fatty acids, what effect does this have on its permeability and fluidity?

Accepted Answer

Decreased fluidity and permeability

Question 15

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

Accepted Answer

They provide mechanical support and are involved in signaling.

Question 16

A mutation causes phosphatidylserine to be exposed on the outer leaflet of the plasma membrane. What is the likely consequence?

Accepted Answer

The cell will be marked for removal by phagocytes.

Question 17

Which of the following best describes the effect of temperature on membrane fluidity?

Accepted Answer

Higher temperature increases fluidity.

Question 18

Which of the following is true regarding the asymmetry of membrane leaflets?

Accepted Answer

The inner leaflet is enriched in phosphatidylserine, which carries a negative charge.

Question 19

Which of the following is a real-world example of membrane carbohydrates mediating cell-environment interaction?

Accepted Answer

Blood type antigens on red blood cells

Question 20

A researcher is studying the effect of cholesterol on membrane permeability. Which equation best describes the relationship between membrane permeability ($$P) $$and cholesterol concentration ($$[C]$$), assuming an inverse relationship?

Accepted Answer

$$P = \frac{k}{[C]}$$

Membrane Structure and Function: Cell Biology Study Notes

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