What event might occur when favorable adaptations build up in a population over many generations?

starvation
extinction
migration
speciation

What percentage of light hits earth's surface directly?

Knowing the importance of the essential elements, why would someone chose a diet that does not address all of them?

You are given an electron micrograph of a bacterial cell. in the micrograph you can clearly see three thin layers of different densities surrounding the cell. based on the micrograph, you can infer that this cell is and would appear after application of the gram stain procedure. gram-negative / pink gram-positive / purple gram-positive / pink gram-negative / purple