A cell might divide... (Choose 4 reasons.) A. to replace old cells.
B. Cells don't divide.
C, as an organism grows.
D. to repair damaged tissue.
E. before it gets too big.

When plants use sunlight to make food, the energy of sunlight is

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

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.