Question 1

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

Accepted Answer

Unsaturated fatty acids have bent hydrocarbon tails due to double bonds, preventing tight packing.

Question 2

A triglyceride molecule is formed by the bonding of which components?

Accepted Answer

Three fatty acids and one glycerol molecule

Question 3

Which type of lipid is primarily responsible for forming the structural foundation of cell membranes?

Accepted Answer

Phospholipids

Question 4

What property of fatty acids makes them hydrophobic?

Accepted Answer

Their long nonpolar hydrocarbon chains

Question 5

Which of the following is a function of waxes in biological systems?

Accepted Answer

Restricting water loss from plant leaves

Question 6

A phospholipid molecule contains:

Accepted Answer

Two fatty acids, a glycerol, and a phosphate group

Question 7

Which of the following statements about saturated fatty acids is correct?

Accepted Answer

They contain only single bonds between carbon atoms in their hydrocarbon tails.

Question 8

Why do phospholipids form bilayers in water?

Accepted Answer

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

Question 9

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

Accepted Answer

Catalyzing chemical reactions as enzymes

Question 10

Steroids are a class of lipids characterized by:

Accepted Answer

A rigid backbone of four carbon rings

Question 11

Which of the following best describes the difference between the structure of a wax and a triglyceride?

Accepted Answer

Waxes have long fatty acid tails bonded to long chain alcohols or carbon rings, while triglycerides have three fatty acids bonded to glycerol.

Question 12

Which of the following lipids is most likely to be found in honeycomb structures made by bees?

Accepted Answer

Waxes

Question 13

If a fatty acid contains 18 carbon atoms and one double bond, what type of fatty acid is it?

Accepted Answer

Unsaturated fatty acid

Question 14

Which of the following is a reason why animal fats are typically solid at room temperature?

Accepted Answer

They are mostly composed of saturated fatty acids, which can pack tightly together.

Question 15

Which chemical group in a fatty acid is responsible for its acidic properties?

Accepted Answer

Carboxyl group ($\mathrm{COOH}$)

Question 16

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

Accepted Answer

They have both hydrophilic (phosphate head) and hydrophobic (fatty acid tails) regions.

Question 17

A scientist discovers a lipid molecule with a rigid backbone of four carbon rings and no fatty acid tails. Which type of lipid is this most likely to be?

Accepted Answer

Steroid

Question 18

Which of the following is a real-world consequence of the hydrophobic nature of lipids?

Accepted Answer

Cell membranes act as barriers to water-soluble substances.

Question 19

Which of the following best explains why phospholipids are critical for cell membrane function?

Accepted Answer

Their amphipathic structure allows them to form bilayers that separate internal and external environments.

Question 20

Which of the following statements about the structure of fatty acids is correct?

Accepted Answer

Fatty acids consist of a carboxyl group attached to a hydrocarbon chain of 4 to 36 carbon atoms.

Lipids: Structure, Types, and Biological Functions

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