During which phase of the cell cycle is a cells Dna copied

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.

Add solid urea to a beaker of water. the beaker gets very cold. is δh favorable or

If you see a sedimentary outcrop and red layers of sand are at the top of pale layers of rock, what does this tell you about the ages of the rock layers?