How does Mendel’s experiment show that traits may be dominant or recessive?
(b) How traits get expressed from parents to offsprings? Explain with an example.
(c) Why are traits acquired during the lifetime of an individual not inherited?
Answers
1) Mendel conducted the experiments using Pisum sativum or pea plant.
He selected homozygous tall (TT) and dwarf (tt) pea plants.
He crossed the tall pea plant with the dwarf pea plant.
It was observed that the F1 generation are all tall plants.
Thus, it was concluded that the gene causing tallness is dominant while the gene causing dwarfness is recessive.
The trait expressing itself in the hybrid is the dominant one.
This experiment proves Mendel’s first law of inheritance.
It states that when a pair of contrasting factors is brought in a hybrid, one factor inhibits the appearance of the other, one which inhibits is the dominant one and which is inhibited is recessive.
2) The gene which decides the appearance of an organism even in the presence of an alternative gene is known as a dominant gene. The trait expressed is known as a dominant trait. The dominant gene is represented by a capital letter. The gene which decides the appearance of an organism only in the presence of another identical gene is called a recessive gene. The trait expressed is known as a recessive trait. The recessive gene is represented by a small letter. For example, Pure tall (TT) pea plant was crossed with dwarf (tt) plant.
F1 Generation: All plants obtained were heterozygous tall (Tt). Plants from F1 generation were self-pollinated to obtain F2 generation.
F2 Generation: One homozygous tall plant (TT), two heterozygous tall plants (Tt) and one homozygous dwarf plant (tt) were obtained.
3)This happens because an acquired trait involves change in non-reproductive tissues (somatic cells) which cannot be passed on to germ cells or the progeny. Therefore, these traits cannot be inherited.
Hope it will help you..
