The 'father of genetics' , Gregor johann mendel started working on the problem of how the variations were passed from one generation to the other in his monastery garden .
From the experiments , he hypothesized that characters were carried as traits and an organism always carried a pair of factors for a character were present in the population.
Consider his experiment with two reeds of peas which had peas of seed color contrasting the characters yellow and green , and they are represented as yellow with 'Y' and green with 'y'. He started cross fertilising pure breeds having contrasting characters.
We here take as an example a characteristic color of pea seeds yellow and green.
CROSS POLLINATING A PURE BREED OF YELLOW AND GREEN GAVE
FIRST FILIAL (F1) GENERATION-ALL SEEDS ARE YELLOW
SECOND FILIAL(F2) GENERATION- HERE ABOT 25% OF THE SEEDS ARE GREEN AND 75% OF THE SEEDS ARE YELLOW-THEY CROSS FERTILISE TO GIVE
THIRD FILIAL (F3) GENERATION
. A set of peas gave only yellow seed giving plants.
.Rest of the yellow seed giving plants gave bout 75% yellow and about 25% of green seed giving plants.
.The set of green peas gave only green seed giving plants.
.every pea plant has two factors which are responsible for producing particular character or trait .
the determining agent is responsible for each trait is called a 'factor'.
.during reproduction one factor from each parent is taken to form progeny
one of these will always dominate the other if mixed together.