Question 1

Which of the following statements best explains why lipids are effective for long-term energy storage in organisms?

Accepted Answer

Lipids are highly reduced, so their oxidation yields more ATP per carbon than carbohydrates.

Question 2

A fatty acid with the formula $C_{18}H_{34}O_2$ contains one double bond. Which property would you expect compared to a saturated fatty acid of the same length?

Accepted Answer

It would have a lower melting point and increase membrane fluidity.

Question 3

Which structural feature distinguishes glycerophospholipids from triacylglycerols?

Accepted Answer

Glycerophospholipids have a phosphate-containing head group attached to glycerol.

Question 4

Which class of membrane lipids is characterized by a carbohydrate moiety linked to the head group?

Accepted Answer

Glycoglycerolipids

Question 5

A patient with a genetic defect in sphingomyelin synthesis would most likely have abnormalities in which cellular structure?

Accepted Answer

Plasma membrane

Question 6

Which of the following best describes the role of cholesterol in biological membranes?

Accepted Answer

It disrupts regular fatty acid chain packing, modulating membrane fluidity.

Question 7

Which of the following is TRUE regarding the fluid mosaic model of biological membranes?

Accepted Answer

Lipids and proteins diffuse freely within the plane of the membrane.

Question 8

Membrane rafts are specialized domains in the plasma membrane. Which of the following is NOT a typical component of membrane rafts?

Accepted Answer

Triacylglycerols

Question 9

Which process is most directly responsible for the rapid movement of water across cell membranes in erythrocytes?

Accepted Answer

Facilitated transport via aquaporins

Question 10

The sodium-potassium ATPase pump moves ions against their concentration gradients. What is the stoichiometry of this reaction?

Accepted Answer

$2K^{+}_{out} + 3Na^{+}_{in} + ATP + H_2O \rightarrow 2K^{+}_{in} + 3Na^{+}_{out} + ADP + P_i$

Question 11

Which of the following statements about facilitated transport is correct?

Accepted Answer

It uses specific pores, carriers, or permeases to accelerate diffusion of certain solutes.

Question 12

Which of the following is a distinguishing feature of ABC transporters?

Accepted Answer

They use ATP hydrolysis to translocate small molecules across membranes.

Question 13

A mutation in the gene encoding the cystic fibrosis transmembrane regulator (CFTR) would most directly affect which type of membrane transport?

Accepted Answer

ATP-dependent chloride ion transport

Question 14

Which of the following best describes the difference between symport and antiport cotransport systems?

Accepted Answer

Symport moves two solutes in the same direction; antiport moves them in opposite directions.

Question 15

In the sodium-glucose cotransport system, which provides the driving force for glucose uptake?

Accepted Answer

The sodium gradient across the membrane

Question 16

Which of the following membrane lipids is NOT amphipathic?

Accepted Answer

Triacylglycerol

Question 17

A researcher isolates a membrane protein that spans the lipid bilayer as an alpha-helix. Which class does this protein most likely belong to?

Accepted Answer

Integral membrane protein

Question 18

Which of the following statements about ion channels is correct?

Accepted Answer

Ion channels allow rapid, selective movement of ions down their concentration gradients.

Question 19

Which of the following would most likely increase the fluidity of a biological membrane?

Accepted Answer

Increasing the proportion of unsaturated (cis double bond) fatty acids

Lipids, Membranes, and Cellular Transport: Structure and Function

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