Question

A pea plant with yellow and round seeds (YYRR) is crossed with a pea plant having green and wrinkled (yyrr) seeds, then in ${F_2}$ generation of this dihybrid cross 320 plants are produced. Out of which 180 plants have some phenotypic character. Identify this phenotype.
A. Yellow and wrinkled seeds
B. Yellow and round seeds
C. Green and round seeds
D. Green and wrinkled seeds.

Answer 1

Hint: Pea plant is used to study genetics by Mendel. He considered seven characters of the pea plant and crossed them in different possible ways and obtained various generations. Dihybrid crosses are those where the two-parent selected for crossing differs in two characters from each other.

Complete answer:
A pea plant with yellow round seeds is crossed with another plant with green wrinkled seeds. The genotype of yellow round seeds is YYRR and the genotype of green wrinkled seeds is yyrr. In the ${F_1}$ generation, the progenies obtained are heterozygous yellow round since yellow and round are dominant characters. The ${F_1}$ generation will be YyRr (Yellow round). Later the ${F_1}$ progeny are self-fertilized and ${F_2}$ progeny are obtained. The ratio of progeny is 9:3:3:1.

Gametes	YR	Yr	yR	yr
YR	YYRRYellow round	YYRrYellow round	YyRRYellow round	YyRrYellow round
Yr	YYRrYellow round	YYrrYellow wrinkled	YyRrYellow round	YyrrYellow wrinkled
yR	YyRRYellow round	YyRrYellow round	yyRRgreen round	yyRrgreen round
yr	YyRrYellow round	YyrrYellow wrinkled	yyRrgreen round	yyrrgreen wrinkled

The phenotype of ${F_2}$ generation is – Yellow round, Yellow wrinkled, Green round, Green wrinkled and the phenotypic ratio of ${F_2}$ generation is 9:3:3:1 respectively.
According to the question, there are 320 plants produced in the ${F_2}$ generation. The phenotype of the ${F_2}$ generation will be Yellow round, Yellow wrinkled, Green round, Green wrinkled.
Yellow and wrinkled seeds- In the ${F_2}$ generation, the ratio of yellow wrinkled seeds formed is 3. Out of 320 plants, the total number of yellow wrinkled seeds formed will be 60 plants that are yellow wrinkled.
Yellow round seeds- In the ${F_2}$ generation, the ratio of yellow round seeds formed is 9. Out of 320 plants, the total number of yellow round seeds formed will be 180 plants are yellow round.
Green and round seeds – In the ${F_2}$ generation the ratio of green and round seeds formed is 3. Out of 320 plants, the total number of green round seeds formed will be 60 plants are green round.
Green and wrinkled seeds- In ${F_2}$ generation the ratio of green and wrinkled seeds formed is 1. Out of 320 plants, the total number of green wrinkled seeds formed will be 20 plants that are green wrinkled.

So, the correct answer is option B.

Note:
Phenotypic character is the set of the observable characteristics of an organism. Genotypic character is an organism set of heritable genes passed from parents to offspring.