Q)A plant homozygous for tall is crossed with a plant homozygous for dwarf, what will be the appearance of the progeny of a cross of F1 with its tall parent.
Answers
Answer:
A cross between pure breeding tall (TT) and dwarf (tt) plant produce all tall hybrids (Tt). The allele/factor that can express itself in the heterozygous individual is called as the dominant factor; here tallness is expressed in heterozygotes and hence is the dominant character. The other factor whose effect is masked by the presence of dominant factor is called as the recessive factor (dwarfism). Selfing of “Tt” produce the phenotypic ratio of 3:1 in F
2
generation which means that both homozygous dominant (TT) and heterozygous dominant (Tt) show “tall” phenotype and homozygous recessive (tt) shows “dwarf” phenotype. Option A is correct. When both recessive and dominant traits are expressed in a heterozygous genotype; it is codominance. If the trait was codominant, the heterozygote would show both tall and dwarf phenotype; thus option B is incorrect. Incomplete dominance is the condition when none of the factors of a gene is dominant, the phenotype of a heterozygous dominant individual is a blend of dominant and recessive traits; thus option C is incorrect. Heredity is the genetic transmission of characters from parent generation to progeny; transmission of tallness/dwarfism is heredity but it is not the reason for appearance tall phenotype in heterozygote or presence of 3:1 ratio in F
2
generation.
Answer by Piyush Ramrao Munde
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