Imagine that we mate two black Labrador dogs with normal vision and find that three of the puppies are like the parents, but one puppy is chocolate with normal vision and another is black with PRA (progressive retinal atrophy, a serious disease of vision). We can conclude that

In the given case, both the parents exhibit black color with normal vision, however, the progenies from these parents exhibit black color with one exhibiting brown color, while one is black in color but exhibiting a condition associated with vision known as PRA. This indicates that both these parents are heterozygous and the brown color and PRA are the recessive traits.  

The progenies showing black normal vision, brown normal vision and black with PRA, indicates that the alleles for these genes have got segregated autonomously of each other.  

black

lasagna

lunch

math