Question

A flower with $Tt$ genotype is cross-pollinated by $TT$ pollens. What will the genotypes of the resulting endosperm and embryo, respectively, be?

• A. TTT, (TT + Tt)
• B. (TTT + TTt), TT
• C. TTt, Tt
• D. TTt, (TT + Tt)

Answer 1

Answer: (D)

A flower with $Tt$ genotype undergoes meiosis during gamete formation. It produces two types, $T$ and $t$. Since, the nuclei of embryo sac are haploid they might either be $T$ or $t$. So, when the two nuclei fuse to form secondary nucleus the genotype of it might be $TT$ or $Tt$ or $tt$. After the fusion with the male gamete (which produces a single type of gamete $T$) the genotype of endosperm will be $TTT$ or $TTt$ or $Ttt$. Same in the case is with embryo. As there are two types of gametes formed from female parent, i.e. $T$ and $t$. The genotype of the embryo will be $TT+Tt$.