Question

Why do multiple and lethal alleles often result in modifications of the classic Mendelian monohybrid and dihybrid ratios?

Select all that apply.

Multiple alleles means that there are more than one gene at a given locus. A diploid organism has one gene locus that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios.

When an essential gene is mutated, it can result in a lethal phenotype. In this case, classic Mendelian monohybrid and dihybrid ratios will not be observed.

Multiple alleles means that the joint expression of several alleles in a heterozygote shows the third (not blended) phenotype. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios.

When an essential gene is mutated, it can result in a lack of dominance. The resulting phenotype is called lethal. In the case of presence of a such allele, classic Mendelian monohybrid and dihybrid ratios will not be observed.

When the expression of a gene masks the effect of a second gene, it can result in a lethal phenotype. In this case, classic Mendelian monohybrid and dihybrid ratios will not be observed.

Multiple alleles means that there are more than two alternatives of a gene at a given locus. A diploid organism has two homologous gene loci that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios.

Answer 1

Multiple allele : The following option is applicable in case of multiple allelic interaction - "Multiple alleles means that there are more than two alternatives of a gene at a given locus. A diploid organism has two homologous gene loci that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios."

The paragraph written as "Multiple alleles means that there are more than one gene at a given locus ........ may not follow typical Mendelian ratios" is indicative of Polygenic inheritance.

"Multiple alleles means that the joint expression of several alleles in a heterozygote shows the third (not blended) phenotype." - this quote indicate the incident of codominant alles.

Lethal allele is said to be the gene a mutation of which leads to the death of the concerned organism. Thus, this is also a deviation from typical Mendelian genotypic and phenotypic ratio as loss of individual occurs here.