Question 1

Which of the following best describes the monomer or subunit of most lipids found in biological membranes?

Accepted Answer

Fatty acids and glycerol

Question 2

Lipids are characterized by their hydrogen to oxygen ratio. Which of the following best represents this ratio in lipids compared to carbohydrates?

Accepted Answer

Lipids have a much higher hydrogen:oxygen ratio than carbohydrates.

Question 3

Which functional group is involved in the formation of ester bonds in triglycerides?

Accepted Answer

Carboxyl group $$\mathrm{(-COOH)}$$ and hydroxyl group $$\mathrm{(-OH)}$$

Question 4

Which of the following best explains why lipids are generally insoluble in water?

Accepted Answer

Lipids are nonpolar and hydrophobic, so they do not interact favorably with water molecules.

Question 5

A triglyceride is formed by the reaction of three fatty acids with one glycerol molecule. What type of reaction is this, and what bond is formed?

Accepted Answer

Dehydration synthesis; ester bond

Question 6

Which of the following statements correctly distinguishes between saturated, monounsaturated, and polyunsaturated fatty acids?

Accepted Answer

Saturated fatty acids have no double bonds; monounsaturated have one double bond; polyunsaturated have two or more double bonds.

Question 7

Which of the following is a major function of lipids in living organisms?

Accepted Answer

Long-term energy storage and insulation

Question 8

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

Accepted Answer

Two fatty acids and a phosphate group attached to a glycerol backbone

Question 9

Steroids are a class of lipids with a distinct structure. Which of the following best describes this structure?

Accepted Answer

Four fused carbon rings

Question 10

Which of the following is NOT a function of waxes in living organisms?

Accepted Answer

Serving as a major energy storage molecule

Question 11

Which of the following best explains why oils are liquid at room temperature while fats are solid?

Accepted Answer

Oils contain more unsaturated fatty acids, which introduce kinks and prevent tight packing.

Question 12

Which of the following is an example of a steroid found in animals?

Accepted Answer

Cholesterol

Question 13

A scientist analyzes a molecule with the formula $$\mathrm{C$$_{27}$$H_{46}O$$}$ and a structure of four fused rings. What type of lipid is this most likely to be?

Accepted Answer

Steroid

Question 14

Which of the following best describes the amphipathic nature of phospholipids?

Accepted Answer

Phospholipids have both hydrophilic and hydrophobic regions.

Question 15

Which of the following chemical reactions is responsible for breaking down triglycerides into their monomers?

Accepted Answer

Hydrolysis

Question 16

A patient is found to have high levels of cholesterol in their blood. Which class of lipid does cholesterol belong to, and what is its structural feature?

Accepted Answer

Steroid; four fused carbon rings

Question 17

Which of the following is a reason why phospholipids form bilayers in water?

Accepted Answer

Their hydrophobic tails avoid water while hydrophilic heads interact with water.

Question 18

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

Accepted Answer

Fats are usually solid at room temperature, while oils are liquid.

Question 19

Which of the following elements are commonly found in lipids?

Accepted Answer

Carbon, hydrogen, oxygen

Question 20

Which of the following best describes the role of ester bonds in lipid structure?

Accepted Answer

Ester bonds link fatty acids to glycerol in triglycerides.

Lipids: Structure, Types, and Functions (Concept 5.3)

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