Q: Which of the following reactions describes the reduction of D-glucose?

$$\mathrm{D\text{-}Glucose + H_2$ \xrightarrow{Pt} D\text{-}Glucitol}$$

Question 1

Which of the following statements best describes the difference between an aldose and a ketose monosaccharide?

Accepted Answer

An aldose contains an aldehyde group, while a ketose contains a ketone group.

Question 2

Which of the following is the correct Fischer projection for D-glucose?

Accepted Answer

A six-carbon chain with the -OH on the chiral carbon farthest from the carbonyl group on the right.

Question 3

Which of the following best explains why sucrose is not a reducing sugar?

Accepted Answer

Both anomeric carbons are involved in the glycosidic bond, leaving no free hemiacetal or hemiketal group.

Question 4

A patient’s fasting blood glucose level is measured at 135 mg/dL on two separate occasions. According to clinical guidelines, what is the most likely diagnosis?

Accepted Answer

Diabetes

Question 5

Which of the following best describes the process of mutarotation?

Accepted Answer

The equilibrium between the α- and β-anomers of a cyclic sugar in aqueous solution.

Question 6

Which of the following polysaccharides is unbranched and contains only β-(1,4)-glycosidic bonds?

Accepted Answer

Cellulose

Question 7

Which of the following reactions describes the reduction of D-glucose?

Accepted Answer

$$\mathrm{D	ext{-}Glucose + H_2$ \xrightarrow{Pt} D	ext{-}Glucitol}$$

Question 8

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

Accepted Answer

Cellulose contains β-(1,4)-glycosidic bonds, which human enzymes cannot break.

Question 9

Which of the following is a correct description of glycogen?

Accepted Answer

It is a highly branched polymer of glucose with α-(1,4)- and α-(1,6)-glycosidic bonds.

Question 10

A solution of D-glucose is tested with Benedict’s reagent. What is the expected observation and why?

Accepted Answer

A red/orange precipitate forms, because glucose is a reducing sugar.

Question 11

Which of the following best describes the structure of maltose?

Accepted Answer

Two glucose units joined by an α-(1,4)-glycosidic bond.

Question 12

Which of the following is a sugar alcohol produced by the reduction of D-glucose?

Accepted Answer

D-Sorbitol (D-Glucitol)

Question 13

Which of the following best describes the difference between the α and β anomers of D-glucose in the Haworth structure?

Accepted Answer

The position of the -OH group on carbon 1: down for α, up for β.

Question 14

Which of the following is a correct statement about the oral glucose tolerance test?

Accepted Answer

A normal blood glucose reading 2 hours after drinking the glucose solution is less than 140 mg/dL.

Question 15

Which of the following is a correct description of lactose?

Accepted Answer

A disaccharide composed of galactose and glucose joined by a β-(1,4)-glycosidic bond.

Question 16

Which of the following best explains why fructose is considered a reducing sugar?

Accepted Answer

Fructose can rearrange to form glucose, which has a free aldehyde group that can be oxidized.

Question 17

Which of the following is a branched polysaccharide containing both α-(1,4)- and α-(1,6)-glycosidic bonds?

Accepted Answer

Amylopectin

Question 18

Which of the following is a real-life consequence of the accumulation of D-sorbitol in the lens of the eye in diabetics?

Accepted Answer

Cataracts

Carbohydrates: Structure, Classification, and Biological Importance

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