Question 1

Which of the following statements best explains why lipids are not considered polymers?

Accepted Answer

Lipids are assembled from smaller molecules but do not consist of repeating monomer units.

Question 2

Which element is NOT a major component of biologically important lipids?

Accepted Answer

Nitrogen ($N$)

Question 3

A triglyceride is formed by the joining of which molecules, and what type of bond is created?

Accepted Answer

Three fatty acids and one glycerol, joined by ester linkages

Question 4

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Unsaturated fatty acids contain one or more double bonds, causing kinks in the hydrocarbon chain.

Question 5

Which type of lipid is a major component of cell membranes and contains both hydrophilic and hydrophobic regions?

Accepted Answer

Phospholipids

Question 6

A patient has high levels of cholesterol in their blood. Which class of lipid is cholesterol a member of, and what is its basic structure?

Accepted Answer

Steroids; characterized by a carbon skeleton consisting of four fused rings

Question 7

Which of the following is TRUE regarding the function of lipids in biological systems?

Accepted Answer

Lipids are involved in energy storage, membrane structure, and signaling.

Question 8

Which statement best explains why unsaturated fats are generally liquid at room temperature?

Accepted Answer

The presence of double bonds creates kinks, preventing tight packing of molecules.

Question 9

Phospholipids form bilayers in water due to their amphipathic nature. Which part of the molecule interacts with water?

Accepted Answer

The phosphate group head

Question 10

Which of the following is a function of steroids in animals?

Accepted Answer

Hormonal signaling, such as sex hormones

Question 11

A scientist analyzes a fat molecule and finds it contains only single bonds between carbon atoms. What type of fat is this, and what is its likely physical state at room temperature?

Accepted Answer

Saturated fat; solid

Question 12

Which equation correctly represents the formation of a triglyceride from glycerol and fatty acids?

Accepted Answer

$\mathrm{glycerol} + 3\ \mathrm{fatty\ acids} \rightarrow \mathrm{triglyceride} + 3\ \mathrm{H_2O}$

Question 13

Which of the following best describes the role of phospholipids in the cell membrane?

Accepted Answer

They create a selectively permeable bilayer due to their hydrophilic heads and hydrophobic tails.

Question 14

Which molecule is NOT classified as a lipid?

Accepted Answer

Cellulose

Question 15

A diet high in saturated fats is associated with increased risk of cardiovascular disease. Which structural feature of saturated fats contributes to this risk?

Accepted Answer

Linear structure that allows tight packing and solid formation at room temperature

Question 16

Which of the following is TRUE about the structure of steroids?

Accepted Answer

Steroids have a backbone of four fused carbon rings.

Question 17

Which of the following lipids is most directly involved in cell signaling?

Accepted Answer

Steroid hormones

Question 18

A mutation causes a cell to produce phospholipids with two saturated fatty acid tails instead of one saturated and one unsaturated. What effect would this likely have on the cell membrane?

Accepted Answer

The membrane would become less fluid and more rigid.

Question 19

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

Accepted Answer

Fats are primarily used for energy storage, while phospholipids are key components of cell membranes.

Lipids and Proteins: Structure, Function, and Biological Importance

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