What do scientist think causes the movement of earth's plate?

Chloroplasts and bacteria are in size. a. similar b. at different ends of the size range c. exactly the same d. none of these

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.

Select the correct answer.what is the observable characteristic of a person called? o a. genotypephenotypeoc.alleleo d.gene