Question 14 Marks
A purebred pea plant with smooth seeds (dominated characteristic) was crossed with a purebred pea plant with wrinkled seeds (recessive characteristic). The $F_{1}$ generation was self-pollinated to give rise to the $F_{2}$ generation.
i. What will be the genotypic ratio of the given $\mathrm{F}_{2}$ generation?
ii. What is the expected observation of the $\mathrm{F}_{2}$ generation of plants?
iii. If a genotype consists of different types of alleles, what is it called?
OR
What is the alternative form of the gene?
i. What will be the genotypic ratio of the given $\mathrm{F}_{2}$ generation?
ii. What is the expected observation of the $\mathrm{F}_{2}$ generation of plants?
iii. If a genotype consists of different types of alleles, what is it called?
OR
What is the alternative form of the gene?
Answer
View full question & answer→ i. In given case, genotypic ratio of $F_{2}$ progeny will be $1: 2: 1$ where one is homozygous dominant, two are heterozygous dominant and one is homozygous recessive.
ii. $\frac{1}{4}$ of them have wrinkled seeds and $\frac{3}{4}$ of them have smooth seeds.
iii. Factors representing the alternate or same form of a character are called alleles. In heterozygous individuals or hybrids, a character is represented by two contrasting alleles. Out of the two contrasting alleles, only one is able to express its effect in the individual. It is called the dominant allele. The other allele which does not show its effect in the heterozygous individual is called the recessive allele, e.g., in the case of hybrid tall pea plants ( Tt ). ' T ' is a dominant allele whereas ' t ' is a recessive allele.
OR
The alternative form of the gene is called Allele. Alleles are a pair of genes that occupy a specific location on a particular chromosome and control the same trait.
ii. $\frac{1}{4}$ of them have wrinkled seeds and $\frac{3}{4}$ of them have smooth seeds.
iii. Factors representing the alternate or same form of a character are called alleles. In heterozygous individuals or hybrids, a character is represented by two contrasting alleles. Out of the two contrasting alleles, only one is able to express its effect in the individual. It is called the dominant allele. The other allele which does not show its effect in the heterozygous individual is called the recessive allele, e.g., in the case of hybrid tall pea plants ( Tt ). ' T ' is a dominant allele whereas ' t ' is a recessive allele.
OR
The alternative form of the gene is called Allele. Alleles are a pair of genes that occupy a specific location on a particular chromosome and control the same trait.