A tomato plant shows the recessive form of a characteristic. What can be said with certainty about its two alleles for that gene?

Erklärung

A dominant allele would have masked the recessive form and the plant would have looked dominant instead, so no dominant allele can be present at all. That rules out the mixed pair as well as any weaker claim that one dominant allele is there, leaving a pair of recessive alleles as the only genotype this appearance allows.