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i)A cross between an individual showing a character for a dominant gene(that is homozygous or heterozygous) with a homozygous recessive individual
OR
a cross between individual(organism) of unknown genotype with a homozygous recessive individual.
ii) It helps in determining the genetic constitution/genotype of an organism.
iii) A set of more than two alleles that may determine a character
example is blood group which can be determined by any two of three alleles i.e. A,B and O
iv) In humans blood groups are determined by three alleles i.e. A,B and O
it is only possible to have two genes at a time
genes A and B are co-dominant while gene O is recessive to genes A and B.
ii) In humans blood is either Rh positive or Rh negative.
People who have Rh antigen are Rh(+ve) while those without Rh antigen in their blood are Rh(-ve).
Rh(+ve) is due to a dominant gene while the recessive gene causes lack of Rh factor.
iii) There are two sex chromosomes in humans, x and y
males are xy and females are xx
in females all ova have x chromosome
in males 50% of sperms contain x chromosomes While 50% of sperms contain y
chromosome.
when a sperm containing x chromosome fuses with an ovum this results into a girl
when a sperm containing y chromosome fuses with an ovum the result is a boy.
Anganifelix answered the question on April 17, 2018 at 11:31
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