Question

researchers can identify the species of an unknown organism using dna barcoding. during dna barcoding, researchers amplify and sequence a specific region of an organisms dna. then, they compare the sequence to those from known species in a reference database to find a match.
a group of researchers used dna barcoding to determine if seafood being sold to consumers was labeled as the correct species. the researchers gathered fish samples from local sellers, extracted dna, and amplified a specific region of the dna from each sample. to ensure their amplification step worked as expected, the researchers visualized the amplified dna fragments to verify that they were the expected size. then, the researchers sequenced the amplified fragments so they could compare those sequences to known species.
which of the following techniques did the researchers most likely use to visualize the amplified dna fragments?
choose 1 answer:
a dna sequencing
b dna gel electrophoresis
c dna extraction
d polymerase chain reaction (pcr)

Explanation:

• Option A: DNA sequencing is for determining the order of nucleotides, not visualizing fragment size.
• Option B: DNA gel electrophoresis separates DNA fragments by size, allowing visualization (e.g., via staining) to check if they are the expected size. This matches the researchers’ goal of verifying fragment size.
• Option C: DNA extraction is for isolating DNA, not visualizing fragments.
• Option D: PCR is for amplifying DNA, not visualizing the amplified fragments.

Answer:

B. DNA gel electrophoresis