In a diploid species of plant, the genes for plant height and fruit shape are syntenic and separated by 18 m.u. Allele D produces tall plants and is dominant to d for short plants, and allele R produces round fruit and is dominant to r for oval fruit.


A plant with the genotype DR/dr produces gametes. Identify gamete genotypes, label parental and recombinant gametes, and give the frequency of each gamete genotype.

Give the information requested.

The gametes produced by an organism with the genotype Rt/rT

A pure-breeding tall plant producing oval fruit as described in Problem 2 is crossed to a pure-breeding short plant producing round fruit.

If the F₁ identified in part (a) are crossed to one another, what proportion of the F₂ are expected to be short and produce round fruit? What proportion are expected to be tall and produce round fruit?

Give the information requested.

Progeny of the cross Rt/rT×rt/rt

A pure-breeding tall plant producing oval fruit as described in Problem 2 is crossed to a pure-breeding short plant producing round fruit.

The F₁ are crossed to short plants producing oval fruit. What are the expected proportions of progeny phenotypes?

Draw a diagram illustrating the alleles on homologous chromosomes for the genotypes given, assuming in each case that the genes reside on the chromosome in the order written.

DFg/DFG

In a diploid species of plant, the genes for plant height and fruit shape are syntenic and separated by 18 m.u. Allele D produces tall plants and is dominant to d for short plants, and allele R produces round fruit and is dominant to r for oval fruit.

Give the same information for a plant with the genotype Dr/dR.