Question

Lathyrus odoratus is an example of which of the following genes?
A. Supplementary genes
B. Complementary genes
C. Lethal genes
D. Codominant genes

Answer 1

Hint lathyrus odoratus is a sweet pea having white and purple flowers . In case of lathyrus odoratus the phenotypic ratio is 9 purple:7 white instead of 9:3:3:1.

Complete answer:- To answer this question you must know examples of supplementary ,complementary ,lethal and codominant genes.
In the Supplementary gene ,the dominant allele of one of two genes governing a character produces phenotypic effect. Thus the dominant allele of the other gene does not produce a phenotypic effect on its own. For example development of agouti (gray) coat color in mice.
In complementary gene interaction both gene loci have homozygous alleles and both of them produce identical phenotype the F2 ratio becomes 9:7 instead of 9:3:3:1. Both dominant alleles when present together with each other are called complementary genes and produce a different phenotype. Example lathyrus odoratus where white flower and purple flower are crossed then the offspring produced in F2 generation in the ratio 9 purple :7 white flower.
Lethal gene is the inheritance of coat colour in mice.he expected a phenotype ratio from a cross of 3 yellow :1 white ,but the observed ratio was 2:1. For example sickle cells anemia.
Codominant gene expressed both in phenotype of a heterozygote. For example flower colour in snapdragons antirrhinum majus having red and white flowers.

Lathyrus odoratus is an example of complementary gene interaction therefore the correct option is (B) complementary genes.

Note:- lathyrus odoratus is a botanical name of the sweet pea flowering plant belonging to the family leguminosae (pea). Sweet peas have been cultivated since the 17th century and a vast number of cultivars are commercially available. Sweet pea earned honor because of its delicious aroma with beautiful flowers. The plant is climbing annually, dicotyledon.