Crossing over in a diploid organism is responsible for

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?

Do you think Mendel's laws of inheritance would have been different if the characters that he chose were located on the same chromosome?

Linkage was first studied by .....

$A$ pure breeding pea plant with the dominant phenotype of character $A$ and recessive phenotype of character $B$ was crossed with another pure breeding plant with the recessive phenotype of $A$ and dominant phenotype of character $B$. An offspring of this cross was crossed with a homozygous recessive for both the characters $A$ and $B$. The following results were obtained:
$22$ were phenotypically dominant for $A$ and recessive for $B$.
$4$ were phenotypically dominant for both $A$ and $B$.
$4$ were phenotypically recessive for both $A$ and $B$.
$24$ were phenotypically recessive for $A$ and dominant for $B$.
These results show that:

Two genes $R$ and $Y$ are located very close on the chromosomal linkage map of maize plant. When $RRYY$ and $rryy$ genotypes are hybridized,then $F_{2}$-segregation will show