In a simple Mendelian monohybrid cross,true-breeding tall plants are crossed with short plants,and the F₁ plants,which are all tall,are allowed to self-pollinate.What fraction of the F₂ generation will be both tall and heterozygous? A) ¹/₈ B) ¹/₄ C) ¹/₃ D) ²/₃ E) ¹/₂

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Quizplus · Accepted Answer

The genotype of the true-breeding tall plant can be represented as SS, and the genotype of the short plant can be represented as ss. When these two plants are crossed, all the F1 generation plants will be Ss, meaning they are heterozygous for the gene controlling plant height, and will all be tall. When the F1 generation plants are self-pollinated, the Punnett square for the resulting F₂ generation would be: | | S | s | |---|---|---| | S | SS | Ss | | s | Ss | ss | As can be seen from the Punnett square, one-fourth (or 25%) of the F₂ generation will be both tall and heterozygous. Therefore, the answer is E.

In a Simple Mendelian Monohybrid Cross,true-Breeding Tall Plants Are Crossed