$A$ recessive mutant is one which:

Mendel published his work on the inheritance of characters in .......... but it remained unrecognized until the year ........ for several reasons.

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.

In a monohybrid cross of plants with red and white flowered plants,Mendel got only red flowered plants. On self-pollinating these $F_1$ plants,he got both red and white flowered plants in a $3:1$ ratio. Explain the basis of using $RR$ and $rr$ symbols to represent the genotype of plants of the parental generation.

.......... is the unit of inheritance.

Based on Mendel's experiments,explain the concepts of factors,dominant/recessive traits,genotype,and phenotype.