Pure line breed refers to

In $Pisum$ $sativum$,two of the seven traits studied by Mendel were linked,as they are located on chromosome number $4$. These traits were:

$A$ gene that is responsible for coding for contrasting traits is known as .....

Discuss the genetic basis of the wrinkled phenotype of pea seed.

Given below are two statements:
Statement $I$: Back cross is the crossing of $F_1$ hybrid with one of the two parents from which they were derived.
Statement $II$: Test cross involves the crossing of $F_1$ hybrid with its homozygous recessive parent.
In light of the above statements,choose the correct answer from the options given below.

Provide definitions/explanations for the following terms:
$1.$ Genetics
$2.$ Heredity