A heat-killed, phosphorescent (light-emitting) strain of bacteria is mixed with a living, non-phosphorescent strain. Further observations of the mixture show that some of the living cells are now phosphorescent. Which of the following observations would provide the best evidence that the ability to phosphoresce is a heritable trait?
A) evidence that DNA was passed from the heat-killed strain to the living strain
B) evidence that protein passed from the heat-killed strain to the living strain
C) especially bright phosphorescence in the living strain
D) phosphorescence in descendants of the living cells

Question

Quizplus · Accepted Answer

If the ability to phosphoresce is a heritable trait, then it should be passed on to descendants of the living cells. Therefore, phosphorescence in descendants of the living cells is the best evidence that the ability to phosphoresce is a heritable trait. Choice A is incorrect because the passage of DNA alone does not necessarily determine if a trait is heritable. Choice B is incorrect because protein passing from the heat-killed strain is unlikely to confer a heritable trait. Choice C is incorrect because bright phosphorescence does not necessarily indicate heritability.

A Heat-Killed, Phosphorescent (Light-Emitting) Strain of Bacteria Is Mixed with a Living