When Lederberg and Tatum Performed Their Experiments on Gene Transfer

Multiple Choice

When Lederberg and Tatum performed their experiments on gene transfer in bacteria that lead to our understanding of conjugation,what were their controls?

A) They mixed strains A and B together.
B) They put strain A on one side of a U-shaped tube and strain B on the other,with a filter between them.
C) They found bio^- met^- cells.
D) They plated strain A and strain B separately onto minimal media plates to screen for spontaneous prototrophs.
E) They observed mating bridges with transmission electron microscopes.