Question

(Choose as many as you deem correct)

The fluctuation test of Luria and Delbruck established that:

a) Bacterial resistance to phages and other bactericides is the result of mutations.

b) Mutations arise as a directed response to environmental change.

c) Mutations occur spontaneously as a result of random processes that can happen at any time and anywhere in the genome.

d) The number of phage-resistant mutants per tube was relatively constant.

Answer 1

Lurua and Delbruck cultured bacteria for several generations. Then they separated these E. Coli bacteria in several tubes and put them with bacteriphages. They wanted to see the number of resistant bacteria in each tube. They wanted to see if the resistance in bacteria was pre-existing or medium nediated.

They found that the mutation in genome caused the bacteria to become resistant. But the number of resistant bacteria varied drastically among the test tubes. This made them conclude that Darwin's theory of random selection applied in all orgsnisms, from simple eukaryotes to complex eukaryotes.

The result also showed that the mutation was not as a result of environmental change.

So option a and c are correct.