Question

Identify the hydrolysis product of starch.

• A. Glucose
• B. Fructose
• C. Galactose
• D. Ribose

Hint:

Keep in mind that starch, glycogen, and cellulose are all homopolymers of glucose. Therefore, the complete hydrolysis of any of these three major polysaccharides will always yield pure glucose!

Answer 1

The Correct Option is A

Step 1: What is starch.
Starch is a big food storage molecule found in plants like rice and potato. It is a polysaccharide, which just means a long chain made of many small sugar units joined together.
Step 2: What are its building blocks.
Starch is made of two parts, amylose and amylopectin. Both of these are built only from one kind of sugar, namely $\alpha$-D-glucose.
Step 3: What hydrolysis means.
Hydrolysis means breaking a molecule apart using water. Here water cuts the links that hold the glucose units together.
Step 4: What gets released.
Since the whole chain is built only from glucose, cutting all the links can only give back glucose. Nothing else can come out.
Step 5: Write it as an equation.
$(\text{C}_6\text{H}_{10}\text{O}_5)_n + n\,\text{H}_2\text{O} \rightarrow n\,\text{C}_6\text{H}_{12}\text{O}_6$, where the product is glucose.
Step 6: Pick the answer.
Fructose, galactose and ribose are different sugars and are not present in starch, so they cannot form. The product is glucose, which is option 1.
\[ \boxed{\text{Glucose}} \]