If a mother has type AB blood, and her son has type AB blood, what are the possible blood types for the father?

As the two strands of DNA are unraveled, which enzyme relieves the strain on the two strands that could otherwise lead to supercoiling?

During S phase of the cell cycle:

A gene that codes for a protein was removed from a eukaryotic cell and inserted into a prokaryotic cell. Although the gene was successfully transcribed and translated, it produced a different protein than it produced in the eukaryotic cell. What is the most likely explanation?

The lactose operon is most likely to be transcribed when

During _______, RNA polymerase synthesizes a molecule of RNA using DNA as a template.

The consequence of nondisjunction in chromosome 21 in humans is ___.

During DNA replication in E.coli, which enzyme opens up the two strands of the DNA double helix?

The display of chromosomes shown below is a ____. karyotype.png 

The tryptophan operon is a repressible operon that is _________.