Final answer:
Aldoses are sugars containing an aldehydic group, and ketoses are sugars containing a ketonic group. Reducing sugars are carbohydrates that react with an oxidizing agent under alkaline conditions to form an aldonic acid. Glucose, galactose, and fructose are examples of reducing sugars.
Step-by-step explanation:
Aldoses are sugars that contain an aldehydic group, such as glucose, galactose, and mannose. Ketoses are sugars that contain a ketonic group, such as fructose and seduloheptulose. Reducing sugars are carbohydrates that react with a mild oxidizing agent under alkaline conditions to form an aldonic acid. For example, D-glucose is a reducing sugar because it can reduce an oxidizing agent.
Glucose and galactose are aldoses, while fructose is a ketose. Therefore, glucose and galactose are reducing sugars, while fructose is also a reducing sugar because it can exist in equilibrium with glucose in basic conditions.
Chemical reactions of carbohydrates show that sugars with a free aldehydic or ketonic group are reducing sugars. Examples of reducing sugars include glucose, fructose, galactose, maltose, and lactose. Non-reducing sugars, like sucrose and trehalose, do not have a free aldehydic or ketonic group.