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Blazing goIITian

Joined:	3 Sep 2008
Post:	485

30 Jan 2009 02:15:46 IST

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The F2 phenotypic ratio of 1:2:1 is obtained in those crosses that exhibit

None

The F2 phenotypic ratio of 1:2:1 is obtained in those crosses that exhibit

complete dominance

partial dominance

co-dominance

both 2 & 3 xplain

what is back cross?whether the back cross & test cross are same plz xplain

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KRRISH

Blazing goIITian

Joined: 10 Nov 2008

Posts: 365

31 Jan 2009 14:06:56 IST

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both 2 and 3.. coz in partial dominance is same as incomplete dominance and in co-dominance, phenotypic ration is same as genotypic ration and is 1:2:1 .. but if complete dominance is present, then 3:1 ratio is obtained as phenotypic ratio.... crossing with the parental individua or parental genotype is known as back cross.... doing the same with recessive individual is test cross

N.P. Singh

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Joined: 17 Dec 2008

Posts: 446

3 Feb 2009 16:33:47 IST

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ANS is both 2 &3 bcoz incomplete dominance and in co-dominance, phenotypic ratio is same as genotypic ratio i.e.is 1:2:1 .but if complete dominance then phenotypic ratio willbe 3:1 ratio & genoty[pic ratio will be 1:2:1

Back cross is croos between F1 and either of parent

Test cross is cross between F1 & reccessive parent

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