Q: Which of the following is the correct Fischer projection for D-fructose?

$$\begin{array}{c} \mathrm{CH}_2\mathrm{OH} \\ | \\ \mathrm{C}=\mathrm{O} \\ | \\ \mathrm{HO}-\mathrm{C}-\mathrm{H} \\ | \\ \mathrm{H}-\mathrm{C}-\mathrm{OH} \\ | \\ \mathrm{H}-\mathrm{C}-\mathrm{OH} \\ | \\ \mathrm{CH}_2\mathrm{OH} \end{array}$$

Question 1

Which of the following statements best describes a pair of enantiomers?

Accepted Answer

They are non-superimposable mirror images of each other.

Question 2

Given the Fischer projection below, identify whether the molecule is a D- or L-enantiomer:

$$\begin{array}{c}
\mathrm{CHO} \
| \
\mathrm{H}-\mathrm{C}-\mathrm{OH} \
| \
\mathrm{HO}-\mathrm{C}-\mathrm{H} \
| \
\mathrm{H}-\mathrm{C}-\mathrm{OH} \
| \
\mathrm{CH}_2\mathrm{OH}
\end{array}$$

Accepted Answer

L-enantiomer

Question 3

Which carbon is used to determine D or L configuration in a Fischer projection of a monosaccharide?

Accepted Answer

The chiral carbon furthest from the carbonyl group

Question 4

Which of the following best describes an epimer?

Accepted Answer

Two sugars that differ in configuration at only one chiral center

Question 5

D-glucose and D-galactose are related in which of the following ways?

Accepted Answer

They are epimers at carbon 4

Question 6

A student draws a Fischer projection of a sugar with the following configuration at the chiral center furthest from the carbonyl: the OH group is on the right. What is the configuration?

Accepted Answer

D

Question 7

Which of the following is true about most naturally occurring carbohydrates?

Accepted Answer

They are D-sugars

Question 8

Which of the following Fischer projections represents the L-enantiomer of D-glucose?

Accepted Answer

All chiral centers are inverted compared to D-glucose

Question 9

If a sugar is a diastereomer of D-glucose, which of the following must be true?

Accepted Answer

It differs at one or more, but not all, chiral centers

Question 10

Which of the following best describes the relationship between D-mannose and D-glucose?

Accepted Answer

They are epimers at carbon 2

Question 11

A patient is found to have a rare sugar in their blood that is the L-enantiomer of glucose. Which of the following statements is true about this sugar?

Accepted Answer

It has the opposite configuration at every chiral center compared to D-glucose

Question 12

Which of the following is NOT a property of enantiomers?

Accepted Answer

They have different chemical properties in achiral environments

Question 13

Which of the following best describes the relationship between D-glucose and L-glucose?

Accepted Answer

They are enantiomers

Question 14

If a sugar differs from D-glucose at both C-2 and C-4, what is the relationship between the two molecules?

Accepted Answer

They are diastereomers

Question 15

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

Accepted Answer

$$\begin{array}{c}
\mathrm{CH}_2\mathrm{OH} \
| \
\mathrm{C}=\mathrm{O} \
| \
\mathrm{HO}-\mathrm{C}-\mathrm{H} \
| \
\mathrm{H}-\mathrm{C}-\mathrm{OH} \
| \
\mathrm{H}-\mathrm{C}-\mathrm{OH} \
| \
\mathrm{CH}_2\mathrm{OH}
\end{array}$$

Question 16

Which of the following would be considered an epimer of D-mannose?

Accepted Answer

A sugar that differs from D-mannose at only one chiral center

Question 17

A chemist isolates a sugar that is a diastereomer of D-galactose. Which of the following is true?

Accepted Answer

It differs from D-galactose at one or more, but not all, chiral centers

Question 18

Which of the following best describes the relationship between D-fructose and L-fructose?

Accepted Answer

They are enantiomers

Question 19

Which of the following is a correct statement about the D/L system for sugars?

Accepted Answer

It is based on the configuration of the chiral center furthest from the carbonyl group

D- and L- Enantiomers and Epimers in Carbohydrates

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