Question

Which of the following sugars is known as fruit sugar?
A. Fructose
B. Glucose
C. Lactose
D. Maltose

Answer 1

Hint: Sugars are simple carbohydrates and are commonly sweet in taste. They are soluble in water and have low molecular weight and not true of those with large molecules. They are widely distributed molecules in both plants and animal tissues. Sugars act as food reserves in the storage parts of plants and in the (liver and muscles) of animals.

Complete answer:
Now, we considered all the options that we are provided with.
Fructose is the sweetest of all naturally occurring sugars. It is also called fruit sugar because of its common occurrence in fruits (except grapes). Nectar and honey contain fructose. The same is called Laevulose (levulose) because of its levorotatory nature.
Glucose is the most widely spread and most important monosaccharides, in living systems. It is a common respiratory substrate. It is commonly called blood sugar and is present in grapes, hence called grape sugar. It is also called dextrose being dextrorotatory.
Lactose is solely of animal origin and is found in the milk of mammals. Human milk contains about 6% (and 0.3% of higher oligosaccharides); cow’s milk, about 4.5% and hence called milk sugar. During pregnancy it may be found in urine.
Maltose does not occur abundantly in nature. The major product of enzymatic hydrolysis of starch is maltose. Sprouting cereals grains are rich in amylases which split the starch present to dextrins and maltose. It is also called malt sugar.

So, the correct answer is “Option A”.

Note:
Monosaccharides are the simple carbohydrate monomer, which cannot be hydrolyzed further into smaller units.
Different sugars have different sweetening indexes.
It is 16, 32 and 100 for lactose, maltose and sucrose respectively.
Fructose has the highest sweetening index of 170.