Question
Explain with an example how traits get expressed.
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Answer
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.
Phenotypic Ratio: 3 : 1
Genotypic Ratio: 1 : 2 : 1
- $F_1$ Generation: All plants obtained were heterozygous tall $(T t)$. Plants from $F_1$ generation were self-pollinated to obtain $F_2$ generation.
- $F _2$ Generation: One homozygous tall plant $( TT )$, two heterozygous tall plants ( Tt ) and one homozygous dwarf plant ( tt ) were obtained.
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