Question

Complete hydrolysis of starch gives :

• A. glucose and fructose in equimolar amounts
• B. galactose and fructose in equimolar amounts
• C. glucose only
• D. glucose and galactose in equimolar amounts

Answer 1

The Correct Option is C

 To understand the complete hydrolysis of starch, let's analyze what starch is and what happens during hydrolysis.

Starch is a polysaccharide. It is composed of long chains of glucose units linked together primarily by α-1,4-glycosidic bonds and sometimes α-1,6-glycosidic bonds in the case of branching (amylopectin). The general formula for starch can be written as \((C_6H_{10}O_5)_n\).

During the process of hydrolysis, starch is broken down into its simplest form, which involves breaking the glycosidic bonds between the glucose units.

Here's the breakdown:

• Starch, upon complete hydrolysis, breaks down into many glucose units. Hydrolysis involves the addition of water molecules (H₂O) and is often catalyzed by enzymes (like amylase) or acids.
• The reaction can be simplified as follows: \(\text{(C}_6\text{H}_{10}\text{O}_5\text{)}_n \, + \, n\text{H}_2\text{O} \, \rightarrow \, n\text{C}_6\text{H}_{12}\text{O}_6\)

From this reaction, we see that the only product of complete starch hydrolysis is glucose.

Now, let's evaluate the options:

• Option 1: Glucose and fructose in equimolar amounts - This is incorrect because the complete hydrolysis of starch results in glucose only, not fructose.
• Option 2: Galactose and fructose in equimolar amounts - This is incorrect because neither galactose nor fructose is produced from starch hydrolysis.
• Option 3: Glucose only - This is correct as explained by the breakdown of starch into glucose.
• Option 4: Glucose and galactose in equimolar amounts - This is incorrect because starch does not hydrolyze to galactose.

 

Hence, the correct answer is: glucose only.