Question

3. In the first mate, you crossed N2 (+/+ wild type) males into morphological mutant (Unc, Dpy, Rol, Lon) hermaphrodites. In the second cross, +/mutant males were crossed into spe/spe sterile hermaphrodites. Why couldn’t you have just crossed Unc, Dpy, or Rol homozygous males directly into the spe/spe hermaphrodites (2 pt)?

Answer 1

After first cross we got +/mutant progeny ( able to produce viable offsprings) . When +/mutant males were crossed with Spe/spe sterile hermaphrodites then half of the progeny will be viable and halfhave and the vigour to reproduce and half of the progeny will be sterile . If mutant homozygous males were directly crossed with sterile hermaphrodites no all mutant sterile offsprings will be obtained that can not reproduce .