Question

A heat-killed phosphorescent strain of bacteria is mixed with a living, non-phosphorescent strain. Some of the living cells are now phosphorescent. Which observation would provide the best evidence that the ability to phosphoresce is a heritable trait? A. The phosphorescent trait is observed in the offspring of the living, non-phosphorescent strain.

B. The phosphorescent trait is observed only in the heat-killed bacteria.
C. The phosphorescent trait is observed in all living cells, regardless of their lineage.
D. The phosphorescent trait is observed only in the heat-killed bacteria, and not in the living cells.

Answer 1

The best evidence for heritability of the phosphorescent trait is A, where the trait is observed in the offspring of the initially non-phosphorescent strain, indicating a transfer and inheritance of genetic material.

Step-by-step explanation:

The observation that would provide the best evidence that the ability to phosphoresce is a heritable trait is A. The phosphorescent trait is observed in the offspring of the living, non-phosphorescent strain. This outcome indicates that the genetic material responsible for phosphorescence was transferred from the heat-killed phosphorescent strain to the living non-phosphorescent strain, and then passed on to the next generation, hence the trait of phosphorescence has become heritable in the once non-phosphorescent population.

This phenomenon is similar to the famous findings of Frederick Griffith's transformation experiments with Streptococcus pneumoniae, where he discovered that the transforming principle was able to turn the non-pathogenic R strain into the pathogenic S strain.