In diploid organisms,crossing over is responsible for which of the following?

The distance between two linked genes on a chromosome is measured in cross-over units,which is:

State the conclusions drawn from Morgan's experiments on linkage and recombination.

What is a linkage group?

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.

What was the phenotypic ratio obtained in the experiment on linkage and recombination performed in Lathyrus odoratus (Sweet Pea)?