DNA is copied during the S Phase of Interphase.  Why do cells copy the DNA?

When listening the levels of orginization in orginisims from the smallest to most complex , which level is just below organs in complexity

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.

How far down have geologists drilled holes ? (science) a: 3.8 km b: 12 km c: 100 m d: 1200 km