Question

Suppose T is dominant to t. T confers tall plant height. In a cross between a parent of unknown genotype and a Tt individual, 50% of the progeny are tall. What is the genotype of the unknown parent?a. TTb. Ttc. impossible to telld. tt

Answer 1

tt

Step-by-step explanation:

The parent of unknown genotype can be one of three genotypes: TT, Tt, or tt. The outcomes of crosses between a heterozygote and a plant of unknown genotype produce different phenotypic ratios among the progeny.

A cross of TT to Tt will produce 50% TT and 50% Tt progeny, all of which have a dominant allele and are tall.

A cross of Tt to Tt will produce 25% TT, 50% Tt, and 25% tt progeny, which results in a 3:1 ratio of tall to short progeny.

A cross of tt to Tt will produce 50% Tt and 50% tt offspring, which results in 50% tall and 50% short progeny, respectively.

Answer 2

D. tt

Because T is dominant and will always be expressed if it is present, if a TT plant or Tt plant were to cross it would give 100% y’all plants since each offspring would have a dominant T gene. The only way to have 50% tall and 50% not tall would be to mate with a homozygous recessive plant with a tt genotype.