Question

In tomato plants, the red skin color (R) is dominant to yellow skin color (r). A red-skinned tomato plant was crossed with a yellow-skinned tomato plant, and the following proportion of ${ F }_{ 1 }$ offspring resulted: 79 red-skinned tomatoes, 68 yellow-skinned tomatoes. What were the genotypes of the P generation?
(a) RR and rr
(b) Rr and RR
(c) Rr and Rr
(d) Rr and rr
(e) None of the above

Answer 1

Hint: R is the red-color gamete and r is the yellow-skin-color gamete. The red color is dominant over the yellow color and almost equal amounts of skinned red and yellow tomatoes are obtained. If a cross is made between the genotypes heterozygous and homozygous recessive gamete as seen in the Punnett square, all these phenotypes in the ${ F }_{ 1 }$ generation will be expressed.

Complete answer: Both the red-skinned tomatoes and yellow-skinned tomatoes will be obtained by crossing Rr and rr in the Punnett square. Thus, the genotypes obtained Rr and rr and the genotypic ratio will be 1:1.

	R	r
r	Rr	rr
r	Rr	rr

Additional Information: - For a certain genetic variant, a monohybrid cross is the fusion of two individuals with homozygous genotypes that result in the opposite phenotype.
- Each allele separates at the moment of gamete formation during meiosis. There is no mixing and various gametes are transferred to characters. Only one form of gametes is produced by homozygotes and different forms of gametes are produced by heterozygotes.
- After conducting experiments on pea plants for seven years, Gregor Mendel suggested the rule of inheritance.
-The laws of inheritance of the Mendel include supremacy law, segregation law, and separate assortment law.
-The segregation law states that every individual has two alleles and that only one allele is passed on to the offspring.
-The law of separate assortment states that one pair of genes is separate from another pair's inheritance.
So, the answer is, “Rr and rr.”

Note: - The plant's genetic structure is known as the genotype. On the opposite, a phenotype is known as the physical appearance of the plant.
-In pairs known as alleles, the genes are passed from parents to offspring.
-During gametogenesis, there is a 50 percent risk of one of the two alleles fusing with the other parent when the chromosomes are halved.
-They are known as homozygous alleles when the alleles are the same, and they are known as heterozygous alleles when the alleles are different.