Which phrase best describes a gene?
(1) a segment of a dna molecule found only in
the body cells of an organism
(2) a segment of a dna molecule found only in
the gametes of an organism
(3) a segment of a dna molecule that contains
the instructions for producing a trait in an
organism
(4) a segment of a dna molecule that contains
the instructions for producing all the
characteristics of an organism

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.