WT Yeast (TRP+) Can Synthesize the Amino Acid Tryptophan and Can

Multiple Choice

WT yeast (TRP+) can synthesize the amino acid tryptophan and can grow on media plates lacking tryptophan. In contrast, mutant alleles (trp-) block tryptophan synthesis and result in an inability of mutant strains to grow on media lacking tryptophan. A diploid yeast was made through the cross M ADE+ × MATa ade-. Meiosis was induced in the diploid strain to produce an ascus with four haploid spores, which were separated and grown on plates lacking tryptophan. How many spores are expec grow into colonies on the plate?

A) 0
B) 3
C) 4
D) 1
E) 2