Question

8. (a) What is the law of dominance of traits ? Explain with an example.
(b) Why are the traits acquired during the life time of an individual not
inherited? Explain.

Answer 1

Law of dominance

Explanation:

(a) Law of dominance was given by Mendel and according to this law any organism which is heterozygous for a trait,only the dominant allele will show a phenotype

• This law can be explained easily by taking the example of height of plants
• Height of plants is expressed as tall and dwarf(tall is dominant over dwarf)
• Tall is expressed as TT genotypically whereas dwarf is expressed as tt(T/t is the trait for height of plant)

• When we cross tall and dwarf plants we get all tall plants expressed as Tt genotypically

(b) The traits which are acquired during the life time of an individual are not inherited because these occur due to the change in environment or the practices done by that individual

• Acquired traits do not interfere with the germ cells or we can say the genetic makeup of DNA
• Examples of these type of traits include skills like painting,singing,swimming and many more(all these are acquired during the life time of an individual)

Answer 2

a) Law of dominance of traits: -In a cross between a pair of contrasting

characters, only one parental character will be expressed in F1

generation which is called dominant trait and the other is called

recessive trait.

For example – in pea plants,

Tall Dwarf /Short

Parents TT tt

Gametes

T t

Tt

F1 All Tall

All plants in F1 generation were tall proving that the gene for tallness

is dominant over the gene for dwarf ness / short, which is not able to

express itself in the presence of dominant trait.

(any other example)

b) Traits acquired by an organism during its lifetime are known as

aquired traits.

These traits are not inherited because they occur in somatic cells

only/do not cause any change in the DNA of the germ cells.