Final answer:
The cross described in the question is a dihybrid cross, which involves two pairs of contrasting traits and generates a unique F2 generation. It's used to predict the inheritance patterns of two separate genes and yields a phenotypic ratio of 9:3:3:1 for the F2 generation when following Mendelian inheritance patterns. Option 1 is correct answer.
Step-by-step explanation:
The type of cross described here is a dihybrid cross. A dihybrid cross involves two pairs of contrasting traits and is used to determine the inheritance pattern of two different genes that are located on separate chromosomes. The question refers to two monohybrid crosses conducted separately, but a dihybrid cross is effectively a combination of two monohybrid crosses that occur simultaneously, each for a different trait.
The Punnett Square Approach for a Dihybrid Cross
To predict the outcome of a dihybrid cross, you can use the Punnett square, a tool named after the British geneticist Reginald Punnett. For example, consider tall plants with inflated pods crossed with dwarf plants with constricted pods. After performing the cross and preventing self-fertilization, you would expect the F1 generation to exhibit the dominant traits. Then, when these F1 heterozygotes are self-crossed, the F2 generation yields a phenotypic ratio of 9:3:3:1 if both gene pairs assort independently according to Mendelian laws.
The F2 generation from a dihybrid cross is unique because it shows the various combinations of the two traits based on the alleles received from each parent. For instance, if Tall (T) and Inflated (I) are the dominant traits, and dwarf (t) and constricted (i) are the recessive traits, the F1 generation from parents with genotypes TTII and ttii will all be TtIi. The F2 generation will then have a variety of genetic combinations based on Mendelian inheritance patterns.
The correct option for the kind of cross described with two pairs of contrasting traits generating a unique F2 generation and involving two separate monohybrid crosses is a dihybrid cross.