What is a top predator?

Which of the following occurs most often in a population when genetic variation and overproduction are present? some organisms have a lower reproductive success than others. some organisms have a higher reproductive success than others. some organisms have no reproductive success. some organisms do not have genetic variation.

How do you transfer mrna into codons ? i'm so confused : (

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.