NTA Official Final Answer Key: DROPPED.

All four biochemical statements (A, C, D, and E) are factually correct statements from NCERT textbooks:

• Statement (A): Purines (A, G) and pyrimidines (C, U, T) are nitrogenous bases.
• Statement (C): Phosphate group is esterified to 5'-OH of a nucleoside.
• Statement (D): RNA nucleotides have a reactive 2'-OH on the ribose.
• Statement (E): Thymine (5-methyl uracil) is a pyrimidine.
  
  Because the statement combinations offered in the options did not allow a valid selection, NTA officially dropped this question in the final answer key and awarded full marks to all candidates.

The correct sequence of steps in DNA fingerprinting is:

• Isolation of DNA from biological sample.
• Digestion of DNA by restriction endonucleases.
• Separation of DNA fragments by electrophoresis.
• Transferring (blotting) of separated DNA fragments to synthetic membranes (nitrocellulose or nylon).
• Hybridisation using labelled VNTR probe.
  6. Detection of hybridised DNA fragments by autoradiography.

In Frederick Griffith's 1928 Streptococcus pneumoniae transformation experiments, the steps proceeded as follows:

• S strain (virulent) injected into mice $\rightarrow$ Mice died.
• R strain (non-virulent) injected into mice $\rightarrow$ Mice lived.
• S strain (heat-killed) injected into mice $\rightarrow$ Mice lived.
• Heat-killed S strain + live R strain injected together $\rightarrow$ Mice died (due to transformation of R strain into virulent S strain).