The y-shaped structure where the dna double helix is actively unwound during dna replication is called the

Replication fork.

Explanation:

Replication fork is exactly where DNA is being replicated, it is a Y-shaped structure caused by helicase enzymes when DNA unwinds, breaking the hydrogen bonds that holds the two strands together. DNA is synthesised using two strands; the leading and lagging strand. The lagging strand discontinues at this point resulting in short fragments called the okazaki fragments.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.