Final answer:
No crossover events between linked loci a, b, c on the same chromosome will result in the parental phenotypes AB and ab, and for a trihybrid cross AaBbCc × AaBbCc, the parental phenotypes would be ABC and abc.
Step-by-step explanation:
The student has asked which two phenotypes are likely to arise from no crossover events when the loci a, b, c are all linked on the same chromosome. When there is no crossover, the alleles at these loci are passed on together in the combinations they are found in the parent.
Therefore, the two phenotypes that would arise from such a scenario would be the ones corresponding to the parental combinations, AB and ab if the genes are completely linked without any crossing over. It is implied that the phenotypes associated with the loci A and B are dominant.
In the context of a trihybrid cross with genotypes AaBbCc × AaBbCc, the phenotypes arising from no crossover events for these linked genes would be ABC and abc, assuming complete linkage and no recombination between these loci during meiosis.
These would represent the parental phenotypes, as they would be the direct genotypical representation of each parent's genetic information without any mixing due to crossover events.