Question

Identify the correct and incorrect statements.

A. The four nucleotide bases are not necessarily present in DNA in exact equal proportions.

B. The total amount of purines are equal to the total amount of pyrimidines.

C. DNA ligase enzyme act to hydrolyse or breakdown a polynucleotide chain into its component nucleotides.

D. Nuclease enzymes are capable of restoring an intact DNA duplex.

• A. B is correct but A, C and D are wrong.
• B. A and B are wrong but C and D are correct.
• C. A, B and C are correct but D is wrong.
• D. A and B are correct but C and D are wrong.
• E. B, C and D are correct but A is wrong.

Answer 1

The correct option is D A and B are correct but C and D are wrong.

• According to Leven's tetranucleotide theory, the four nucleotidess present in the DNA are in equal molar proportion and are not necessarily present in exactly equal proportion.
• According to Chargaff's rules, the DNA from any cell of all organisms pyrimidine and purine should be in the ratio of 1:1 (base Pair Rule). He further concluded that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.
• DNA ligase facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond.
• Nuclease is an enzyme that cleaves nucleic acids.
  

Thus, the correct answer is option D.