Question

Which of the following statements are correct regarding amino acids?
A. They are substituted methanes.
B. Serine is an aromatic amino acid.
C. Valine is a neutral amino acid.
D. Lysine is an acidic amino acid.
Choose the correct answer from the options given below:

• A. C and D only
• B. A and C only
• C. B and C only
• D. A and B only

Hint:

Remember the classification: Acidic = Glutamic acid (A-G), Basic = Lysine/Arginine (B-L), Neutral = Valine (N-V).

Answer 1

The Correct Option is B

Step 1 : Understanding the Question
The question requires verification of the chemical structure and side-chain classification of specific amino acids.
Step 2 : Key Formulas and approach
Approach by checking the general formula $R\text{-}CH(NH_2)COOH$ and the specific properties of the "R" group for Serine, Valine, and Lysine.
Step 3 : Detailed Explanation

Structure (A): Amino acids are considered (A) substituted methanes because the alpha-carbon is bonded to four different groups, replacing the hydrogens of $CH_4$. This is true.

Serine (B): Serine is a hydroxy-amino acid, (B) not aromatic. Aromatic ones are Tyrosine, Phenylalanine, and Tryptophan. This is false.

Valine (C): Valine has a non-polar side chain and one of each functional group, making it (C) neutral. This is true.

Lysine (D): Lysine is a (D) basic amino acid, not acidic. Statement D is false.

Step 4 : Final Answer
Only A and C are correct. Thus, the correct choice is option (C).