Which is the correct statement?

Options

A. Starch is polymer of `alpha`-glucose
B. Amylose is a component of cellulose
C. Proteins are composed of only one type of aminoacids
D. In cyclic structure of furanose, there are five carbons and one oxygen atom

Answer

To determine which statement is correct among the given options, let's analyze each statement one by one:

1. **Statement A: Starch is a polymer of alpha-glucose.**
- Starch is indeed a polysaccharide that is composed of long chains of alpha-glucose units. It consists of two main components: amylose (which is mostly linear) and amylopectin (which is branched). Therefore, this statement is **true**.

2. **Statement B: Amylose is a component of cellulose.**
- This statement is false. Amylose is a component of starch, not cellulose. Cellulose is made up of beta-glucose units. Therefore, this statement is **false**.

3. **Statement C: Proteins are composed of only one type of amino acid.**
- This statement is incorrect. Proteins are made up of 20 different amino acids, which can be combined in various sequences to form different proteins. Therefore, this statement is **false**.

4. **Statement D: In the cyclic structure of furanose, there are five carbon atoms and one oxygen atom.**
- The term "furanose" refers to a five-membered ring structure that includes four carbon atoms and one oxygen atom. Therefore, the statement that there are five carbon atoms in the cyclic structure of furanose is **false**.

Based on the analysis above, the only correct statement is **Statement A: Starch is a polymer of alpha-glucose**.

### Summary of the Correct Statement:
- **Correct Statement:** Starch is a polymer of alpha-glucose.