Who used the frequency of recombination as a measure of the distance between genes on a chromosome and mapped their position?

Who mapped the position of genes on chromosomes by using the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes?

In $Lathyrus$ $odoratus$,a hybrid blue-flowered and long-pollen plant is test-crossed with a homozygous recessive red-flowered and round-pollen plant. How many parental types are obtained when genes are present in the $cis$ stage in parents (in $\%$)?

When the number of recombinant progeny is usually less than the number expected in independent assortment, it is called:

In a diploid organism,crossing over is responsible for ..........

Mendel studied seven pairs of traits in pea plants,which allow for $21$ possible combinations. If you are told that one of these combinations does not show independent assortment in a subsequent study,what would be your reaction?