Q15 of 59 Page 1

With the help of an example justify the following statement:

"A trait may be inherited, but may not be expressed."

Mendel's experiments show that the

(a) According to Mendel’s view of dominant trait, the characteristics or the trait of an organism is determined by the internal factors, these factors always occur in pairs. Out of the two traits, only one of them expresses itself and is known as dominant. The other one which is not expressed is known as Recessive trait.


It can be understood with the help of Mendel’s experiment , when a tall pea plant and a dwarf pea plant is crossed then, the plants appeared in F1 generation are found to be tall which proves that in F1 generation, the dominant was tall character and dwarf were recessive, but in F2 generation, the plants were dwarf. It can be shown as follows:



In Mendel's experiment with pea plants, when he cross-bed a tall pea plant with a short plea plant, he found that the first generation (F1) was of only tall plants. In the F1 progeny, no short plants were obtained. However, in the F2 generation, both tall and short plants were obtained in the ratio 3:1 respectively. In the F2 generation, both traits-tallness and shortness were inherited where the tall character was the dominant trait and short character was the recessive trait.


In F2 progeny, there were both tall and dwarf pea plants. The ratio of dwarf and pea plants was found to be 3:2 which confirmed that in F2 progeny, both the characteristics were inherited and the tall character of pea plant was found to be dominative and dwarf to be recessive. This was the law of segregation which says that when plants of different traits were crossed, then in the first progeny only the dominant character was observed whereas in F2 progeny both dominant and recessive traits were obtained.


Hence it proves that "A trait may be inherited, but may not be expressed."


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