Question

Two non-allelic genes produce the new phenotype when present together but fail to do so independently then it is called as
A. Epistasis
B. Polygene
C. Non complementary gene
D. Complementary gene

Answer 1

Hint: Alike DNA alleles are also a genetic sequence that are responsible for traits. Non allelic genes are alleles at different places of loci of chromosomes but in different ways of interaction it can affect one gene over the other. Phenotype is a set of characteristics observed in an individual which is resultant of interaction between environment and genotype.

Complete Answer:
- Epistasis: It is a type of gene interaction where the phenotypic expression of one gene is masked by the other gene.
- Polygene: A specific type of phenotype is observed only when a group of genes are expressed together. Such genes are called phenotypic genes
- Non complementary gene: It is a rare phenomenon where, despite the presence of dominant alleles at both the loci, the recessive alleles of different genes fail to be complementary.
- Complementary gene: Two non-allelic genes produce the new phenotype when present together but fail to do so independently then it is called a complementary gene.

Therefore the correct answer is (d) complementary gene.

Note: In complementary gene interaction, both the genes mask the effect of each other contributing to a single characteristic. Due to complementation, the Mendelian ratio is modified from 9:3:3:1 to 9:7.