Class 12th Biology 2014 Set2 Delhi Board Paper Solution
How does the gene 'I' control ABO blood groups in humans ? Write the effect the gene has on the structure of red blood cells.
OR
Write the types of sex-determination mechanisms the following crosses show. Give an example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ
In humans, the ABO blood groups are controlled by a gene called gene. It has three alleles, namely IA, IB and i. A person possesses any two of the three alleles. IA and IB dominate over i. But with each other, IA and IB are co-dominant.
Table Showing the Genetic Basis of Blood Groups in Human Population is given as follows
These alleles helps to determine the blood group of a person. The plasma membrane of red blood cells has sugar polymers that protrude out from its surface and the kind of sugar is regulated by the gene 'I' of ABO blood group. The alleles IA and IB produce A and B types of sugar, while allele i does not produce any sugar.
OR
(i) The type of sex determination mechanism shown in female XX with male XO is male heterogamety. Example- Humans
(ii) The type of sex determination mechanism shown in female ZW with male ZZ is female heterogamety. Example- Birds
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