What is the name of the pea species used by Bateson and Punnett in their experiments?

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

Who put forward the "Theory of linkage"?

When a cluster of genes shows linkage behaviour,they:

In female $Drosophila$,linked genes show recombination during meiosis. However,such recombination does not occur during sperm formation in male $Drosophila$. Why?

Genes $p, q,$ and $r$ are arranged on a chromosome. If the recombination frequency between $p$ and $q$ is $10 \%$,the recombination frequency between $q$ and $r$ is $20 \%$,and the recombination frequency between $p$ and $r$ is $10 \%$,what is the order of the genes on the chromosome?