The frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes was explained by

Which traits did Morgan choose for the male and female $Drosophila$ respectively to explain linkage and recombination?

Which of the following is true about linkage?
$I.$ It is a phenomenon in which more recombinants are produced in $F_{2}$-generation.
$II.$ More parental combinations are produced in $F_{2}$-generation.
$III.$ Genotypes which are present in $F_{1}$ hybrid reappear in high frequency in $F_{2}$-generation.
$IV.$ It is a phenomenon in which two chromosomes are linked.

Which of the following statements is not true of two genes that show $50\%$ recombination frequency?

Generation of non-parental gene combinations is termed as

The term 'crossing over' was coined by