Test crosses Transitional Reasoning Practice

Questions

1. 1.

   A researcher investigates the inheritance of fruit color in tomato plants, where red fruit ($R$) is completely dominant to yellow fruit ($r$). To identify the unknown genotype of a red-fruited plant, the researcher crosses it with a yellow-fruited plant. This cross produces 48 red-fruited and 52 yellow-fruited offspring. Based on this experimental outcome, which of the following conclusions is correct?

   • A) The unknown parent was homozygous dominant ($RR$), and the yellow offspring arose solely due to spontaneous somatic mutations.
   • B) Both parent plants were heterozygous ($Rr$), which typically results in equal proportions of dominant and recessive offspring.
   • C) The unknown parent was heterozygous ($Rr$), because producing recessive offspring requires receiving a recessive allele from each parent.
   • D) The cross indicates that yellow fruit is the dominant trait, as a recessive phenotype cannot appear in the first generation.

Answers and step-by-step solutions appear after you finish the test.