Speciation occurs during the evolutionary development, or phylogeny, of a species. in which of the following situations can speciation occur?

when a population becomes extinct.
when two populations are reproductively isolated.
when a population becomes interbred.
when two populations merge to become one population.

Once a woman attains puberty, her overuse mature and release one egg per ovarian cycle. which hormone stimulates this event?

Animal bodies (and even plant bodies for that matter) are complex enough that life couldn't exist without enzymes. enzymes are usually large, complex biological catalysts that are expensive to make. enzymes speed up the rate of chemical reactions without being used up during the reaction (they can be reused many times). they are highly specific in the reactions they regulate. knowing what enzymes are and how they function, why does this explain why complex life forms could not exist if there were no enzymes.

What enzyme is most important for dna replication and why?