When do both hemispheres receive the same amount of the sun’s energy?
only winter solstice
only autumnal equinox
only vernal equinox
both autumnal equinox and vernal equinox

In trying to determine whether dna or protein is the genetic material, hershey and chase made use of which of the following facts? a) dna contains sulfur, whereas protein does not. b) dna contains phosphorus, whereas protein does not. c) dna contains nitrogen, whereas protein does not. d) dna contains purines, whereas protein includes pyrimidines.