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?

Define/Explain: Linkage.

$A$ 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:

Which of the following combinations of characters selected by Mendel shows linkage?

The percentage of crossing over will be more if:

Linked genes are separated by: