Does mrna have codons or anti-codons

Why is it important to reduce the number of chromosomes in half when forming gametes for sexual reproduction?

1) what three conditions must be present for minerals to form through natural processes? 2) why are minerals considered inorganic substances? 3) how do oxides differ from other minerals that contain oxygen atoms? 4) how is a sulfide different from a sulfate? what makes native elements unique?

1. which of the following transport mechanisms utilizes energy? a. osmosis b. diffusion c. facilitated diffusion d. endocytosis