Youre an orchid breeder and have noticed that you have a few

You\'re an orchid breeder and have noticed that you have a few plants that display a totally novel golden coloring pattern. This purple and gold pattern has basically made you a LEGEND in your horticulture club, and now your best friend wants to use your sweet orchids in their wedding. Obviously, getting a pure breeder line would be ideal for cranking up production... because you pal is going to need A LOT of flowers. But this is proving to be a challenge; every time two golden orchids are crossed, you end up with a fair number of gold flowers, but still a significant number of orchids featuring the standard white coloration. In your most recent purple and gold orchid self cross, you ended up with 113 gold and 57 standard orchids. All other such mating gave similar phenotypic offspring ratios. What\'s going on here? And explain why you think that. (lessthanorequalto 4 sentences)

Solution

Mutation leading to Incomplete dominant and lethal allele: The pure breeding white and purple varieties exhibit the incomplete dominance as a result of mutation leading to gold variety. Now, since the selfing of heterozygous gold orchid gives gold and standard orchids in 2:1 ratio, the homozygous recessive or homozygous dominant genotype is lethal giving only two phenotypes in F₂ generation.