Question 1

Which of the following statements best explains why sucrose does NOT give a positive Benedict's test?

Accepted Answer

Both anomeric carbons in sucrose are involved in the glycosidic bond, so there is no free anomeric –OH group.

Question 2

A carbohydrate sample gives a positive Molisch test, a negative Barfoed test, and a blue-black color with iodine. What is the most likely identity of the sample?

Accepted Answer

Starch

Question 3

Which of the following best describes the structural difference between amylose and cellulose?

Accepted Answer

Amylose has α(1→4) glycosidic bonds; cellulose has β(1→4) glycosidic bonds.

Question 4

Which of the following reactions is an example of saponification?

Accepted Answer

$$\mathrm{CH_3COOCH_2CH_3} + \mathrm{NaOH} \rightarrow \mathrm{CH_3COONa} + \mathrm{CH_3CH_2OH}$$

Question 5

A student adds bromine solution to two unknown fats. Sample A rapidly decolorizes the bromine, while Sample B does not. Which conclusion is most accurate?

Accepted Answer

Sample A is an unsaturated fat; Sample B is a saturated fat.

Question 6

Which of the following best explains why humans cannot digest cellulose?

Accepted Answer

Cellulose contains β(1→4) glycosidic bonds, and humans lack the enzyme β-glucosidase.

Question 7

Which of the following statements about the CAN (Ceric Ammonium Nitrate) test is correct?

Accepted Answer

It gives a positive color change with alcohols and carboxylic acids, but not with esters.

Question 8

Which of the following best describes the amphipathic nature of a soap molecule?

Accepted Answer

It has a long nonpolar hydrocarbon tail and a polar carboxylate head.

Question 9

Which of the following is the correct IUPAC name for the compound $$\mathrm{CH_3CH_2COOH}$$?

Accepted Answer

Propanoic acid

Question 10

A patient is prescribed acetaminophen for pain relief. Which functional group is present in acetaminophen, and how does its mechanism differ from aspirin?

Accepted Answer

Amide; acts centrally in the CNS and does not inhibit COX enzymes in peripheral tissue.

Question 11

Which of the following best describes the structure of a glycerophospholipid in cell membranes?

Accepted Answer

Glycerol backbone, two fatty acids, one phosphate group, and a polar alcohol head group.

Question 12

Which of the following is a correct word equation for the saponification of a fat?

Accepted Answer

Triacylglycerol + 3 NaOH $$\rightarrow$$ glycerol + 3 fatty acid sodium salts (soaps)

Question 13

Which of the following best explains why trans fats are considered a health concern?

Accepted Answer

Trans double bonds result in straighter chains that pack more like saturated fats, increasing the risk of plaque buildup.

Question 14

Which of the following statements about LDL and HDL is correct?

Accepted Answer

LDL delivers cholesterol to tissues and high levels increase plaque risk; HDL returns cholesterol to the liver and is protective.

Question 15

Which of the following best describes the reaction that forms an amide?

Accepted Answer

Carboxylic acid + amine + heat $$\rightarrow$$ amide + water

Question 16

A sample gives a positive Barfoed test (red precipitate in 5 minutes) and a positive Benedict's test. Which of the following is the most likely identity of the sample?

Accepted Answer

Monosaccharide such as glucose or fructose

Question 17

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

Accepted Answer

It regulates membrane fluidity and serves as a precursor for steroid hormones.

Question 18

Which of the following is a correct description of mutarotation in glucose?

Accepted Answer

Interconversion between α and β anomers via the open-chain form in water, reaching equilibrium.

Question 19

Which of the following best explains why essential fatty acids must be obtained from the diet?

Accepted Answer

Humans lack the enzymes to synthesize certain double bonds present in essential fatty acids.

Carbohydrates, Carboxylic Acids & Derivatives, and Lipids: Study Guide with Lab Applications

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