ï»¿ Point mutation involves from Biology Principles of Inheritance and Variation Class 12 Nagaland Board

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Principles of Inheritance and Variation

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Point mutation involves

• insertion

• change in the single base pair

• duplication

• deletion

B.

change in the single base pair

The point mutations involve alterations in the structure of gene by altering the structure of DNA. Point mutations are of two types- (i) base pair substitution and (ii) Frameshift substitution.
Insertion is the addition of one of more nitrogenous bases to a nucleotide chain.
Duplication is the presence of one block of genes more than once in the haploid component.
Deletion is the removal of one or more nitrogenous bases from a nucleotide chain.

The point mutations involve alterations in the structure of gene by altering the structure of DNA. Point mutations are of two types- (i) base pair substitution and (ii) Frameshift substitution.
Insertion is the addition of one of more nitrogenous bases to a nucleotide chain.
Duplication is the presence of one block of genes more than once in the haploid component.
Deletion is the removal of one or more nitrogenous bases from a nucleotide chain.

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What for symbols AA and Aa stand ?

AA : Homozygous dominant, Aa : Heterozygous dominant.
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Name one trait that does not blend.

Sex trait .
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Give one example of genetic trait for each of the following in humans : (i) Lethality (ii) Multiple allelism.

(i) Lethality : Sickle cell anaemia.

(ii) Multiple allelism : ABO blood groups.

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Mention the phenomenon of pleiotropy by giving an example.

Pleiotropy. When one gene controls more than one phenotypic character it is termed as pleiotropy.

Example : Sickle cell anaemia.

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Name the plant that shows incomplete dominance in respect of the colour of its flower.

The plany which shoes incomplete dominace in respect of the colour of its flower is -

Snapdragron ( Antirrhinum majus)

Or

Mirabilis jalapa (Four-O- Clock plant ).
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