What is the main difference between an isotope and an ion? a. an ion has extra protons. b. an isotope has extra neutrons. c. isotopes are radioactive while ions are not. d. an ion always has a positive or a negative charge.

Well its not D, Ions always have a negative charge. By process of elimination, I'm assuming its C. Which is logical as well, so this is the correct answer.

The answer would be c, white eyes are homozygous recessive. in the early 1900s, morgan conducted several experiments with vinegar  flies (drosophila). one  sample revealed an anomaly: a  white-eyed, single male fly. he attempted to breed this fly with the typical red-eyed females. the offspring were all red-eyed. using flies from this new generation (brother-sister pairs)  produced some red-eyed and a few white-eyed flies. the white-eyed were all male. in later experiments, he was able to produce white-eyed females. this proved that white eyes are not lethal to either sex (ruling out a and b). since the percentage of white eyes to red eyes is so low, white eyes are not a dominant trait. it would be a recessive trait.