In a plant in which fuzzy leaves (F) are dominant over smooth leaves (f), which cross will produce only smooth-leaved offspring?

To determine which cross will produce only smooth-leaved offspring, it is essential to understand the principles of genetic inheritance, particularly dominant and recessive traits. In this scenario, fuzzy leaves are represented by the dominant allele (F), and smooth leaves are represented by the recessive allele (f).

When looking at the genetic combinations, only the genotype with two recessive alleles (ff) will yield offspring with the smooth-leaved phenotype because the smooth trait requires no dominant F allele present. The ff cross results in offspring that inherit one recessive f allele from each parent, ensuring that all progeny will also be ff and thus exhibit smooth leaves.

With this understanding, if you cross two individuals that both carry the dominant allele (such as FF or Ff), or even a combination of dominant and recessive alleles, there will be a chance of producing offspring with the fuzzy leaf phenotype, which is not compatible with producing only smooth-leaved plants. Therefore, the only combination guaranteed to produce smooth-leaved offspring is one that involves two parents that are both homozygous recessive (ff).