Question

Which of the following is the ketose most abundant in fruits? A. fructose B. glucose C. proline D. glycerol

Short answer

A. fructose

Step-by-step solution

Identify the Ketose

Understand that a ketose is a type of sugar molecule that contains a ketone group. Among the given options, look at which ones are sugars and determine which ones are ketoses.

Scan the Options

Examine the provided choices: A. fructose, B. glucose, C. proline, D. glycerol. First, eliminate options that are not sugars. Proline and glycerol are not sugars. Proline is an amino acid, and glycerol is a simple polyol.

Determine the Type of Sugar

Differentiate between aldoses and ketoses among the remaining options. Glucose is an aldose sugar as it contains an aldehyde group. Fructose is a ketose sugar because it has a ketone group.

Conclude the Answer

Among the options, fructose is a ketose and is known to be abundant in fruits.

Key concepts

ketose identification

Ketoses are a type of sugar molecule that contain a ketone functional group. Identifying a ketose means looking for sugars that have a carbonyl group (C=O) bonded to two other carbon atoms, which forms a ketone. Unlike aldoses, which have an aldehyde group, ketoses are characterized by this internal positioning of the carbonyl group. It's important to note that not all sugars are ketoses. For example, among the options in the exercise: proline is an amino acid and glycerol is a polyol, so neither is a sugar. Fructose and glucose are both sugars, but fructose is the ketose because it has the ketone group.

carbohydrate structures

Carbohydrates are biological molecules made up of carbon, hydrogen, and oxygen. They come in simple forms like sugars and complex forms like starches and fibers. Structure-wise, carbohydrates can be classified based on the presence and position of the carbonyl group (C=O) and the number of carbons. Monosaccharides, the simplest form of carbohydrates, might be categorized as aldoses or ketoses. Monosaccharides have a backbone of carbon atoms bonded to hydroxyl (OH) groups. Aldoses have an aldehyde group (carbonyl at the end), while ketoses have a ketone group (carbonyl in the middle). For instance, glucose is an aldose, while fructose is a ketose. The arrangement of atoms in the structures affects both their function and reactivity.

sugar classification

Sugars can be classified based on the functional group they contain and the number of carbon atoms (such as triose, tetrose, pentose, hexose, etc.). This classification system allows us to predict the behavior and role of different sugars in biological systems. Here’s how you can classify sugars:

• Sugars with an aldehyde group are called aldoses.
• Sugars with a ketone group are called ketoses.
• Sugars with three carbon atoms are called trioses.
• Sugars with four carbon atoms are called tetroses.
• Sugars with five carbon atoms are called pentoses.
• Sugars with six carbon atoms are called hexoses.

Following this scheme, glucose is classified as an aldohexose (an aldose with six carbons), and fructose is classified as a ketohexose (a ketose with six carbons). This detailed classification helps biochemists understand the structure, function, and metabolism of different carbohydrates.