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Generally, the monohybrid cross is used to determine the dominance relationship between two alleles. The cross begins with the parental generation. One parent is homozygous for one allele, and the other parent is homozygous for the other allele. The offspring make up the first filial generation.
The forked-line method (also known as the tree method and the branching system) can also solve dihybrid and multi-hybrid crosses. A problem is converted to a series of monohybrid crosses, and the results are combined in a tree. However, a tree produces the same result as a Punnett square in less time and with more clarity.
In conducting a monohybrid cross, Mendel initiated the experiment with a pair of pea plants exhibiting contrasting traits, one being tall and the other dwarf. Through cross-pollination, the resulting offspring plants manifested the tall trait. These first-generation hybrids were termed F1, with their offspring referred to as Filial or F1 progeny.
Mules and hinnies are examples of reciprocal hybrids. Kunga, a cross between a donkey and a Syrian wild ass. Zebroids. Zeedonk or zonkey, a zebra/donkey cross. Zorse, a zebra/horse cross; Zony or zetland, a zebra/pony cross ("zony" is a generic term; "zetland" is specifically a hybrid of the Shetland pony breed with a zebra) Superfamily ...
Mendel found support for this law in his dihybrid cross experiments. In his monohybrid crosses, an idealized 3:1 ratio between dominant and recessive phenotypes resulted. In dihybrid crosses, however, he found a 9:3:3:1 ratios. This shows that each of the two alleles is inherited independently from the other, with a 3:1 phenotypic ratio for each.
The more genes involved in the cross, the more the distribution of the genotypes will resemble a normal, or Gaussian distribution. [9] This shows that multifactorial inheritance is polygenic, and genetic frequencies can be predicted by way of a polyhybrid Mendelian cross. Phenotypic frequencies are a different matter, especially if they are ...
For example, suppose a biologist wished to identify whether a hypothetical allele Z, a variant of some gene A, is on the male or female sex chromosome. They might first cross a Z-trait female with an A-trait male and observe the offspring. Next, they would cross an A-trait female with a Z-trait male and observe the offspring.
In the example pictured to the right, RRYY/rryy parents result in F 1 offspring that are heterozygous for both R and Y (RrYy). [4] This is a dihybrid cross of two heterozygous parents. The traits observed in this cross are the same traits that Mendel was observing for his experiments. This cross results in the expected phenotypic ratio of 9:3:3:1.