NEET Biology question
Statements I. The four nucleotide bases are not necessarily present in DNA in exact equal proportions. II. The total amount of purines are equal to the total amount of pyrimidines. III. DNA ligase enzyme act to hydrolyse or breakdown a polynucleotide chain into its component nucleotides. IV. Nuclease enzymes are capable of restoring an intact DNA duplex. Of the above statements, how many are correct?
Answer: (D)
Solution
Statements I and II are true: base composition can vary between species (not necessarily equal proportions), while total purines (A+G) always equal total pyrimidines (T+C) by Chargaff's rule. Statements III and IV describe the roles backwards —
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