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Principles of Inheritance and Variation

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Biology

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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

Test cross involves

  • crossing between two genotypes with recessive trait

  • crossing between two F1 hybrids

  • crossing the F1 hybrid with a double recessive genotype

  • crossing between two genotypes with dominant trait


C.

crossing the F1 hybrid with a double recessive genotype

The test cross involves the crossing of F1 hybrid with a double recessive genotypic parent. By test cross, the heterozygocity and homozygocity of the organism can be tested.
Thus, the offspring will be 100% dominant, if the individual which crossed with recessive parent i.e., (tt) was homozygous dominant and ratio will be 50% dominant and 50% recessive if the individual was heterozygous dominant. In dihybrid test cross, ratio will be 1:1:1:1.

The test cross involves the crossing of F1 hybrid with a double recessive genotypic parent. By test cross, the heterozygocity and homozygocity of the organism can be tested.
Thus, the offspring will be 100% dominant, if the individual which crossed with recessive parent i.e., (tt) was homozygous dominant and ratio will be 50% dominant and 50% recessive if the individual was heterozygous dominant. In dihybrid test cross, ratio will be 1:1:1:1.

427 Views

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 ).
1012 Views

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.

825 Views

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.

815 Views

Name one trait that does not blend.

Sex trait .
1181 Views

What for symbols AA and Aa stand ?

AA : Homozygous dominant, Aa : Heterozygous dominant.
772 Views