What are the levels of structural organization in the body of a shark

The use of dna as evidence in criminal investigations became possible because of the

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.

What is thought to have caused the mass extinction at the end of the cretaceous period?