<span>Many sexually active american adolescents fail to avoid pregnancy because they are not educated on contraceptive methods. </span>
<h2><em>In general, a scientific law is the description of an observed phenomenon. It doesn't explain why the phenomenon exists or what causes it. The explanation of a phenomenon is called a scientific theory. It is a misconception that theories turn into laws with enough research</em></h2>
Answer:
<u>d. the cells in primary cell cultures do not divide.</u>
A key difference between primary cell cultures and secondary cell lines is that<u> the cells in primary cell cultures do not divide.</u>
<u>hope</u><u> </u><u>it</u><u> </u><u>helped</u><u> </u><u>you</u><u> </u>
Explanation:
<em>The main difference between primary and secondary cell culture is that the primary cell culture contains the cells directly obtained from host tissue, whereas the secondary cell culture contains sub-cultured cells from primary cell culture.</em>