Contrasting pair of factors in Mendelian crosses

The contrasting pair of factors in Mendelian crosses are called allelomorphs, also known as alleles. These alleles are alternative forms of a gene that occupy the same position on homologous chromosomes. They determine the expression of a specific trait and are responsible for the variability observed in inherited characteristics.

Alleles and Mendelian Crosses
Mendelian crosses involve the crossing of individuals with different alleles for a specific trait. These alleles may exhibit contrasting characteristics, such as tall vs. short height in pea plants or red vs. white flower color. The alleles for a particular trait segregate during gamete formation and then recombine in offspring, following the principles of Mendelian genetics.

Multiple Alleles and Alloloci
While multiple alleles exist for certain traits, such as blood type in humans, Mendelian crosses typically involve only two alleles. Multiple alleles refer to the presence of more than two alternative forms of a gene in a population. However, in a specific individual, only two alleles are present, one on each homologous chromosome.

The term "alloloci" is not commonly used in the context of Mendelian crosses. Instead, the term "allelomorphs" is used to describe the contrasting pair of alleles involved in a cross. Alloloci, on the other hand, refers to different loci or positions on the chromosome that contain alleles for different genes.

Paramorphs and their Role
Paramorphs are not directly related to the contrasting pair of factors in Mendelian crosses. Paramorphs are mutated forms of a gene that exhibit altered phenotypic expressions compared to the wild-type allele. They can be classified as either gain-of-function or loss-of-function mutations.

While paramorphs can contribute to genetic variation, they are not the primary focus when studying Mendelian crosses. Mendelian genetics primarily focuses on the segregation and recombination of alleles, which occur between two contrasting allelomorphs for a particular trait.

Conclusion
In Mendelian crosses, the contrasting pair of factors are referred to as allelomorphs or alleles. These alleles determine the expression of specific traits and segregate during gamete formation. The term "allelomorphs" is used instead of "alloloci" to describe the alternative forms of a gene involved in a cross. Paramorphs, on the other hand, are mutated forms of a gene that exhibit altered phenotypic expressions and are not directly related to Mendelian crosses.