Question

In a PCR, which of the following components is not required?
A. Nucleotide precursors
B. A primer containing 3'-OH
C. DNA helicase to separate the strands
D. DNA polymerase to catalyse the reaction

Answer 1

Hint:-As per the question we've got to consider the polymerase chain reaction of the biotechnology, in which the tools sort of a primer and a few enzymes are required, also in an exceedingly thermally balanced environment.

Complete Answer:-We know that polymerase chain reaction occurs in DNA, for which some tools are required i.e. for separation of the strands, for initiation of reaction a primer and for activation some enzymes also are required that are called catalysts or catalase enzymes. Other enzymes like DNA polymerase etc. are required.
But there's no need for nucleotide precursors.

Additional info:
Nucleotide precursors-that's are the activated precursors of nucleic acids. As such, they're necessary for the replication of the genome and also the transcription of the genetic information into RNA which is named organic phenomenon. Also, the nucleic acids component of an adenine nucleotide, ATP, is the universal currency of energy.
Primer: A primer may be a short, single-stranded DNA sequence employed in the polymerase chain reaction (PCR) technique for biosynthesis. In the PCR method, a pair of DNA primers are employed to hybridize with the sample DNA and define the region of the DNA that may be amplified. Primers also are observed as oligonucleotides i.e having 2-9 pairs of nucleotides.
 DNA polymerase: A DNA polymerase could be a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphate. These enzymes are essential for DNA replication and typically add groups to make two identical DNA duplicates from one original DNA duplication.
So A is the correct option.

Note:- We've got to resolve this kind of question in step with the terms which provide the options of questions that's why it's easy to know and answered quickly. As the term indicates the nucleotide precursors means only another form of nucleic acid.