You amplify the same gene from two different people using PCR (polymerase chain reaction). When you electrophorese the two samples on a gel, you see that two bands are present in the sample from Individual 1, whereas only one band is present in the sample from Individual 2. What is a likely explanation for this outcome?

Based on the information provided within the question it can be said that the most likely explanation for this scenario would be that Individual 1 is heterozygous, while Individual 2 is homozygous. Meaning that Individual 1 most likely inherited two different genes from both people while individual 2 most likely inherited the same gene from both individuals which is why they showed up as one.