The pH scale measures how basic or acidic a substance is, and it ranges from 0 to 14. On the pH scale, a pH of 7 is neutral, less than 7 is acidic and higher than 7 is basic.
Earth's history. In the worst one, 250 million years ago, 96 percent of marine species and 70 percent of land species died off. It took millions of years to recover.
<em>During dna replication, the enzyme dna polymerase adds new nucleotides to the </em><em>3</em><em>'</em><em> end of the sugar in the growing strand</em>
Alleles are two different forms of a single gene.
