Chapter 12, Problem 1ITD

Summary Introduction

To review:

Rice is grown in flooded conditions. There are many varieties of the same that can be tolerant and intolerant. The true breeding-tolerant varieties are FR13A, BKNFR, and Kurk, while the true breeding-intolerant varieties are $\text{IR42\hspace{0.17em}and\hspace{0.17em}NB}$. The tolerant ones are crossed with intolerant strains, which results in the F₁ generation, and then they are interbred to give the F₂ generation. The crosses are as follows:

1. ${\text{F}}_2$ results of a cross:	Number of plants
	Tolerant (Alive)	Intolerant (Dead)	Total
$\text{IR42}\times \text{FR13A}$	$187$	$77$	$264$
$\text{IR42}\times \text{BKNFR}$	$192$	$73$	$265$
$\text{NB}\times \text{Kurk}$	$142$	$52$	$195$

On the basis of the data given for the various crosses, justify that it supports that tolerance is a dominant trait with the help of genotypes and phenotypes.

Introduction:

A homozygous allelic pair is one that has the same genes, both coding either for dominant genes or recessive genes. A heterozygous allelic pair is one that contains two genes coding for dominant genes and recessive genes. Two plants that differ in one trait only are crossed in the case of a monohybrid cross. They can be either homozygous or heterozygous. When a homozygous dominant trait is crossed with a recessive trait, or heterozygous dominant traits are self-crossed, it produces a $3:1$ ratio of progeny.