Question 1

Which of the following best describes why lipids are largely insoluble in water?

Accepted Answer

They contain a high proportion of nonpolar C-C and C-H bonds.

Question 2

Which of the following is NOT a function of triacylglycerols in mammals?

Accepted Answer

Serving as a precursor for steroid hormones

Question 3

A fatty acid with the formula $$\mathrm{C$$_{18}$$H_{34}O_2$}$$ contains one double bond. Which term best describes this molecule?

Accepted Answer

Monounsaturated fatty acid

Question 4

Which of the following statements about phospholipids is TRUE?

Accepted Answer

They are amphipathic, containing both hydrophilic and hydrophobic regions.

Question 5

What is the effect of increasing the number of double bonds in the fatty acid tails of phospholipids on membrane properties?

Accepted Answer

It increases membrane fluidity and permeability.

Question 6

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It reduces membrane permeability by fitting between phospholipids.

Question 7

A patient has a genetic disorder that prevents the formation of ester linkages. Which class of lipids would be most directly affected?

Accepted Answer

Triacylglycerols

Question 8

Which of the following molecules would cross a pure phospholipid bilayer most rapidly?

Accepted Answer

$$\mathrm{O_2$}$$

Question 9

Which of the following adaptations would you expect in the membrane lipids of plants living in hot environments?

Accepted Answer

An increase in saturated fatty acids to decrease membrane fluidity.

Question 10

Which of the following best describes the structure of a steroid?

Accepted Answer

A bulky, four-ring structure

Question 11

Which of the following is a correct comparison between fats and oils?

Accepted Answer

Fats are solid at room temperature due to more saturated fatty acids, while oils are liquid due to more unsaturated fatty acids.

Question 12

Which of the following best explains why soap can dissolve grease?

Accepted Answer

Soap molecules are amphipathic and form micelles around grease, trapping it in the hydrophobic core.

Question 13

Which of the following is a direct consequence of the amphipathic nature of phospholipids?

Accepted Answer

They spontaneously form bilayers in aqueous environments.

Question 14

Which of the following statements about membrane permeability is correct?

Accepted Answer

Membranes with more unsaturated fatty acids are more permeable to small molecules.

Question 15

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

It acts as a buffer, reducing changes in membrane fluidity caused by temperature shifts.

Question 16

Which of the following is a correct statement about the permeability of a phospholipid bilayer to $$\mathrm{Na^+}$$ and $$\mathrm{O_2$}$$?

Accepted Answer

$$\mathrm{O_2$}$$ crosses more easily because it is small and nonpolar, while $$\mathrm{Na^+} is $$charged and cannot cross without assistance.

Question 17

Which of the following is a function of lipids in cells?

Accepted Answer

All of the above

Question 18

Which of the following best explains why unsaturated fatty acids are typically liquid at room temperature?

Accepted Answer

The kinks caused by cis double bonds prevent tight packing of molecules.

Question 19

Which of the following is NOT a component of a phospholipid?

Accepted Answer

Three fatty acids

Question 20

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

Accepted Answer

Higher temperature increases membrane fluidity by increasing the movement of phospholipids.

Lipids: Structure, Function, and Membrane Properties

Study Guide - Practice Questions