In addition to random genetic mutations, what are the 2 other reasons organisms descend with
modifications. In other words, 2 other sources
of variation amona living things

What does polymerase chain reaction (pcr) do? o a. separates dna fragments by size o b. cuts a dna sample into fragments o c. provides an overall picture of a person's chromosomes o d. makes more copies of a sample of dna

Which areas of earth receive the most precipitation on average? a. tropics b. temperate zones c. regions near 30? n and s latitudes d. polar zones 1

Why are some people more concerned about shark survival than about shark attacks?