Question

Aldose: What type of monosaccharides are fructose, glucose, and xylose? To which family do they belong based on their functional groups?

• A. \( \text{Fructose is a ketose, glucose and xylose are aldoses.} \)
• B. \( \text{Fructose and glucose are ketoses, xylose is an aldose.} \)
• C. \( \text{All three are aldoses.} \)
• D. \( \text{All three are ketoses.} \)

Hint:

Monosaccharides are classified into aldoses or ketoses based on the presence of an aldehyde group (\( -CHO \)) or a keto group (\( -C=O \)). This distinction helps identify their structure and behavior in biochemical processes.

Answer 1

The Correct Option is A

Monosaccharides are simple sugars classified based on their functional groups. The two main classifications are aldoses and ketoses, which are determined by the presence of either an aldehyde or a keto group. Step 1: Identifying Aldoses and Ketoses.
Aldoses are sugars that contain an aldehyde group (\( -CHO \)), which is typically located at the first carbon atom in the molecule. Ketoses are sugars that contain a keto group (\( -C=O \)), which is usually located at the second carbon atom in the molecule. Step 2: Functional Groups of Fructose, Glucose, and Xylose.
Let’s analyze the functional groups of each monosaccharide: Fructose is a ketose because it contains a keto group at the second carbon atom, making it a ketohexose (6-carbon ketose). Glucose is an aldose because it contains an aldehyde group at the first carbon atom, making it an aldohexose (6-carbon aldose). Xylose is also an aldose because it contains an aldehyde group at the first carbon atom, making it an aldopentose (5-carbon aldose). Step 3: Family Classification.
Glucose: This monosaccharide belongs to the aldohexose family due to its 6 carbon atoms and aldehyde group. Xylose: This monosaccharide belongs to the aldopentose family due to its 5 carbon atoms and aldehyde group. Fructose: This monosaccharide belongs to the ketohexose family due to its 6 carbon atoms and keto group. Thus, the correct conclusion is: \[ \text{Fructose is a ketose, glucose and xylose are aldoses.} \] Therefore, the correct answer is \( \mathbf{(1)} \).