Question

Complete dominance does not occur in
A. Mirabilis jalapa
B. Oenothera lamarckiana
C. Pisum sativum
D. Lathyrus odoratus

Answer 1

Hint: Dominance is the term used in genetics and describes the phenomenon of one variant of a gene on a chromosome masking. It can also be defined as overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant of the gene is called dominant and the other is called recessive.

Complete answer:
There are three forms of dominance of a gene which are complete dominance, incomplete dominance and codominance. In incomplete dominance the phenotype of the heterozygous genotype is different from the often intermediate to the phenotypes of the homozygous genotypes. In genetics, if a heterozygote's phenotype is exactly between the two homozygotes, the phenotype is said to exhibit no dominance at all. Codominance occurs when the both alleles contribute and are visible in phenotype. In codominance, the allelic products co-exist in the phenotype and are different from incomplete dominance.
 In complete dominance the effect of one allele in a heterozygous genotype overcomes the effect of the other allele. The allele that overcomes the effect of other alleles is called dominant allele and the other allele is called the recessive allele. In complete dominance the phenotype of the heterozygote is unidentified from that of the dominant homozygote. The examples are Oenothera lamarckiana, Pisum sativum and Lathyrus odoratus.

Hence, the correct option is A. Mirabilis jalapa .

Note: The concept of dominance was introduced by Gregor Johann Mendel and is considered as “Father of Genetics”, first used this term in 1860. He worked on the pea plant to observe various laws of genetics.