Question

The information contained in DNA is used to synthesize proteins that are necessary for the functioning of life. DNA is composed of four nucleotides: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). The information contained in DNA can then be thought of as a sequence of these four nucleotides: A, T, C, and G. DNA has coding and non-coding regions. Coding regions—where the sequence of these nucleotides are read in groups of three to produce individual amino acids—constitute only about 2% of human DNA. Based only on the information provided above, which one of the following statements can be logically inferred with certainty? 

(i) The majority of human DNA has no role in the synthesis of proteins. 
(ii) The function of about 98% of human DNA is not understood.

• A. only (i)
• B. only (ii)
• C. both (i) and (ii)
• D. neither (i) nor (ii)

Hint:

Always distinguish between "does not code for proteins" and "function is not known." Logical inference questions often hinge on precise wording.

Answer 1

The Correct Option is A

Step 1: Facts from the passage. - Coding DNA that produces amino acids (protein coding regions) = only about 2% of human DNA. - Remaining 98% = non-coding DNA (does not code for proteins).

Step 2: Analyze statement (i). "The majority of human DNA has no role in the synthesis of proteins." This is correct because only 2% is coding, hence the remaining 98% does not contribute to protein synthesis.

Step 3: Analyze statement (ii). "The function of about 98% of human DNA is not understood." The passage only says that 98% does not code for proteins. It does not say that its function is unknown (it may have regulatory or structural roles). So this cannot be inferred with certainty.

Final Answer: \[ \boxed{\text{only (i)}} \]