Question

A biologist intends to use a polymerase chain reaction to perform a genetic task. The biologist probably is trying to
A. discover new genes.
B. clone a gene.
C. cut DNA into many small fragments.
D. isolate DNA from a living cell.

Answer 1

Hint: PCR denotes Polymerase chain reaction (PCR). It is a widely used method of DNA amplification. The method was introduced by Kary Mullis. PCR is a method used in the laboratory to create millions of copies of a specific section of DNA.
Complete Step-by-step answer:
PCR is a method to significantly increase the numbers of a certain sequence of DNA (or an entire gene). This method amplifies gene in-vitro to generate billions of copies of certain DNA in a short time. This method is most useful when cloning DNA since prior knowledge of the DNA sequence must first be obtained.
A gene variant is a permanent change in the DNA sequence that forms a gene. This kind of genetic change was formerly known as a gene mutation, but because changes in DNA do not always cause disease, it is thought that gene variant is a more precise term.
Cleavage defines the cutting of DNA to get DNA fragments. Double-stranded DNA can be cleaved at a particular site using restriction enzymes. DNA fragments cut by restriction enzymes are referred to as restriction fragments. The DNA cleavage occurs away from the recognition location: more than 400 bp away to as far as 7000 bp.
Gel electrophoresis is the lab method used to divide mixtures of RNA, DNA, or proteins by molecular size. In gel electrophoresis, the molecules to be separated are pushed through an electrical field through a gel containing small pores. Gel electrophoresis is being used for a range of purposes, like obtaining DNA fingerprints for forensic purposes, checking a PCR reaction, and for paternity testing.
Therefore the correct answer is Option B.
Note: PCR is an integral component of biotechnology, diagnostics, medical biology, molecular biology research, forensic analysis, etc. The amplified DNA can be sequenced, cloned, and visualised by gel electrophoresis.