Read the Information Below and Then Answer the Questions That

Multiple Choice

Read the information below and then answer the questions that follow. In an experiment similar to those by Beadle and Tatum, Neurospora spores were mutated and grown in minimal medium test tubes. Mutants unable to grow without the amino acid "L"were isolated. Compounds A, B, and C are precursors to L. The following data are generated by providing these compounds to the mutants.
Data: All strains grow if given compound L.
Strains that grow given compound B also grow if given A or C.
Strains that grow given compound C do not grow if given only B or A.
Strains that grow given compound A will also grow if given C, but not if given only B.
-How many enzymes are in the pathway, from the one that modifies the first compound to the one whose product is amino acid L?

A) 4
B) 7
C) 5
D) 3
E) 6