Question 1

Which of the following statements best explains why triglycerides with unsaturated fatty acids tend to be oils at room temperature, while those with saturated fatty acids are fats?

Accepted Answer

Unsaturated fatty acids have cis double bonds that introduce kinks, preventing tight packing and lowering the melting point.

Question 2

Which of the following best describes the process of saponification?

Accepted Answer

The base-catalyzed hydrolysis of triglycerides to produce glycerol and soap.

Question 3

Which of the following equations correctly represents the saponification of tristearin with sodium hydroxide?

Accepted Answer

$$\mathrm{C$$_{57}$$H_{110}O_6$} + 3\ \mathrm{NaOH} \rightarrow \mathrm{C_3H_8O_3} + 3\ \mathrm{C$$_{18}$$H_{35}O_2Na$$}$

Question 4

Why are omega-3 and omega-6 fatty acids considered essential in the human diet?

Accepted Answer

Humans lack the enzyme to introduce double bonds beyond C-9 in fatty acids.

Question 5

Which of the following best explains why soaps are less effective in hard water?

Accepted Answer

Soap forms insoluble salts with Ca$$^{2+}$$, Mg$$^{2+}$$, and Fe$$^{3+}$$ ions, leading to precipitation.

Question 6

Which of the following is a correct description of a phospholipid's structure?

Accepted Answer

A glycerol backbone esterified to two fatty acids and one phosphoric acid group.

Question 7

Which of the following statements about steroids is correct?

Accepted Answer

Steroids are classified as simple lipids because they do not undergo hydrolysis.

Question 8

Which of the following best describes the structural difference between testosterone and estradiol?

Accepted Answer

Estradiol has an aromatic A ring, while testosterone does not.

Question 9

Which of the following is a function of prostaglandins in the human body?

Accepted Answer

Regulation of blood pressure, blood clotting, and the inflammatory response.

Question 10

Which of the following best describes the structure of a micelle formed by soap in water?

Accepted Answer

A spherical aggregate with hydrophilic carboxylate heads on the surface and hydrophobic tails inside.

Question 11

Which of the following is a correct equation for the complete hydrogenation of trilinolein?

Accepted Answer

$$\mathrm{C$$_{57}$$H_{98}O_6$} + 6\ \mathrm{H_2$} \rightarrow \mathrm{C$$_{57}$$H_{110}O_6$}$$

Question 12

Which of the following is a reason why biodiesel is more suitable than vegetable oil for use in diesel engines?

Accepted Answer

Biodiesel consists of fatty acid methyl esters, which are more volatile and have lower viscosity.

Question 13

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

Accepted Answer

An ester of a long-chain fatty acid with a long-chain alcohol.

Question 14

Which of the following statements about terpenes is correct?

Accepted Answer

Terpenes are composed of isoprene units joined in a head-to-tail fashion.

Question 15

Which of the following is true about the melting points of fatty acids?

Accepted Answer

Saturated fatty acids have higher melting points than unsaturated fatty acids of the same chain length.

Question 16

Which of the following best explains why phospholipids form bilayers in water?

Accepted Answer

Their amphipathic nature causes hydrophobic tails to avoid water and hydrophilic heads to interact with water.

Question 17

Which of the following is a correct statement about sphingolipids?

Accepted Answer

Sphingolipids contain sphingosine, an amino alcohol, instead of glycerol.

Question 18

Which of the following is a correct description of the function of cholesterol in cell membranes?

Accepted Answer

Cholesterol modulates membrane fluidity and serves as a precursor for steroid hormones.

Lipids: Structure, Classification, and Biological Roles

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