plz answer soon

Asked by  | 1st Feb, 2010, 04:28: PM

Expert Answer:

Mendel basically put forward 3 laws to explain the pattern of inheritance. These laws are popularly known as laws of inheritance.

i) Law of dominance - In a cross between 2 organisms pure for any pair of contrasting characters, the character which appears first in the hybrid of F1 generation is called dominant and the one which is suppressed is called recessive. For example - In the crossing of pure tall with pure dwarf, only tall character appeared in F1 generation, hence tallness is dominant over dwarfness. (However this law is not universally true.)

 

ii) Law of segregation of characters and purity of gametes - In an individual, a particular trait is controlled by a pair of factors or genes, each contributed by one of the parents. These factors separate or segregate from one another during gamete formation. Each gamete has only one of a pair of contrasting characters. So the gamete is pure for a particular trait.

For example - When 2 hybrid individuals Tt and Tt are crossed, we get one homozygous dwarf in the progeny. This dwarf, therefore must have received one gamete containing character of dwarfness from each of the hybrid parents. This is possible only if

iii) Law of independent assortment - In crossing over, if 2 or more traits are involved (say height and colour), their factors i.e. genes assort independently, irrespective of the combinations present in the parents.  Each one of the pair of contrasting characters will coexist with either of another paired type.

Answered by  | 2nd Feb, 2010, 07:17: AM

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