The blood group known as the universal donor is: MCQ with Answer and Explanation

Explanation:
The central dogma, proposed by Francis Crick, describes the flow of genetic information from DNA to RNA (transcription) and then to protein (translation). Information cannot flow from protein to nucleic acid. However, exceptions exist: reverse transcription (RNA → DNA) in retroviruses, and some regulatory RNA functions. The fundamental principle still holds.

Explanation:
In prokaryotes, DNA polymerase I has 5'→3' exonuclease activity that removes the RNA primer and fills the gap with DNA. DNA polymerase III adds nucleotides to the growing strand. Ligase seals the nicks. Helicase unwinds DNA. In eukaryotes, RNase H removes primers and DNA polymerase δ fills the gap.

Explanation:
Polymerase Chain Reaction (PCR) is a powerful molecular technique used to exponentially amplify a specific segment of DNA, creating millions of copies from a small initial sample. Gel electrophoresis is a laboratory method used to separate DNA, RNA, or protein molecules based on their size and charge by applying an electric field through a gel matrix. Restriction enzymes are molecular scissors that cut DNA at specific sequences; DNA ligase is the enzyme that joins DNA fragments together. Thus, statements 1 and 2 are correct.