Question

In a monohybrid cross, if the gene for tall (T) plants was incompletely dominant over the gene for short (t) plants, what would be the predicted result of crossing an intermediate (Tt) plant with a tall (TT) plant?

Answer 1

50% Tt or intermediate and 50% TT or tall

Answer 2

Half of the offsprings will be Intermediate (Tt), while the other half will be Tall (TT).

Step-by-step explanation:

This is a typical monohybrid cross because it involves a single gene, which is coding for height in plant.

According to the question, the allele for tallness (T) is incompletely dominant over that of shortness (t).

Incomplete dominance is a phenomenon in inheritance that occurs when the two alleles of a gene seem equally effective in their influence on a trait i.e. a dominant allele does not completely mask the effects of the recessive allele in a heterozygous state, hence, the resulting offspring has a phenotype that shows the blending of both alleles.

In this case, the allele for tallness (T) could not completely mask the expression of the allele for shortness (t), hence, an offspring different from both parents results (intermediate).

In a cross between an intermediate plant (Tt) and a tall plant (TT). The alleles of each plant are first separated into gametes according to Mendel's law of segregation (See attached image for details).

Based on the cross in the image attached, among the offsprings expected to result, half (1/2 or 50%) of them are tall (TT) while the other half (1/2 or 50%) are intermediate (Tt).