Answer:
DNA molecular weight standard controls, also known as DNA ladders
Explanation:
A DNA ladder is a molecular-weight size marker used to identify the size of the PCR products in a gel electrophoresis. The DNA ladder consists of a solution containing double-stranded DNA fragments with different molecular weights including, among others, 50 base pairs (bp), 100 bp, 1000 bp and 3000 bp DNA fragments. The concentration of each DNA fragment in the DNA ladder must be sufficiently high to be visualized on the electrophoresis gel.
