Question

A cross between two pea plants tall with axial flowers and dwarf with terminal flowers produced offsprings tall with axial flowers and tall with terminal flowers in the ratio 1:1.What will be the genotype of parents?
A) TTAa X ttaa
B) TtAa X ttaa
C) TtAA X ttaa
D) TTAA X ttaa

Answer 1

For two features, a dihybrid cross describes a mating experiment between two species that are identically hybrid. A hybrid organism is one that is heterozygous, indicating that at a certain genetic location, or locus, it bears two different alleles.

Complete answer:

A dihybrid organism with two distinct genetic loci is one that is heterozygous. Gregor Mendel conducted dihybrid crosses on pea plants in 1865 and discovered a simple genetic law called the Independent Assortment Law.
By first crossing two homozygous parental organisms which differed with respect to two traits, Mendel began his experiments. At a specific genetic locus, an organism that is homozygous for a particular feature bears two similar alleles.
A Punnett square is a graphical representation of an offspring's potential genotypes resulting from a specific cross or breeding event. Creating a Punnett square involves comprehension of the parents' genetic makeup.
Punnett squares can reliably predict the ratios of different measurable traits as well as their underlying genetic makeup in large-scale studies, such as those performed by Mendel.
The F1 hybrids were all phenotypically tall at the cross between tall and dwarf pea plants, but their genotypes were not only TT but also Tt. Think of a heterozygous hybrid plant called Tt. When it shapes gametes, in the gametes, the factors T and t segregate in a 1:1 ratio.
This means that 50 percent of the heterozygous hybrid F1 gametes bear factor T and 50 percent bear factor t. Mendel crossed a hybrid plant like that (Tt) with a real breeding plant, a dwarf variety (tt). The recessive factor t was carried by all gametes of a homozygous dwarf plant.
Each recessive parent's gamete has a 50 percent chance of combining with a gamete carrying T and a 50 percent chance of combining with the heterozygous parent's t gamete.
This should result in 50 percent of progeny displaying the tall phenotype and Tt genetic constitution, while 50 percent of the progeny should be phenotypically dwarf with tt genotype, as shown below:

p	Tall (Tt)	dwarf(tt)
Gametes	tall-50%(T)	dwarf-50%(t)
Progeny	Tt	tt
tall:dwarf	1:1

Similar to the above explained experiment the dominant parent should be heterozygous to permit the expression of a recessive allele in the next generation in order to have both axial and terminal flowers in the progeny. This renders the tall plant genotype "TTAa" with axial flowers.

Thus the correct answer is option(A) TtAa X ttaa.

Note: Mendel found from his experiment that the pairs of characteristics in the parental generation were sorted separately from each other, from one generation to the next.