Short Answer TypeWhat are 'true breeding lines' that are used to study inheritance pattern of traits in plants?
How does the gene 'I' control ABO blood groups in humans? Write the effect the gene has on the structure of red blood cells.
Write the types of sex-determination mechanisms the following crosses show. Give an example of each type
(i) Female XX with Male XO
Write the types of sex-determination mechanisms the following crosses show. Give an example of each type
(ii) Female ZW with Male ZZ
A colour-blind child is born to a normal couple. Work out a cross to show how it is possible. Mention the sex of this child.
Mendel published his work on inheritance of characters in 1865, but it remained unrecognized till 1900. Give three reasons for the delay in accepting his work.
A geneticist interested in studying variations and patterns of inheritance in living beings prefers to choose organisms for experiments with shorter life cycle. Provide a reason.
A teacher wants his/her students to find the genotype of pea plants bearing purple coloured flowers in their school garden. Name and explain the cross that will make it possible.
Long Answer TypeExplain the genetic basis of blood grouping in human population.
In humans, the blood groups are controlled by a gene called gene I. It has three alleles, namely IA, IB and i. The plasma membrane of the red blood cells has sugar polymers that protrude from the surface and the kind of sugar is controlled by the gene. The alleles IA and IB produce a slightly different sugar while i do not produce any sugar. Since humans are diploid, each person can have different combinations of the three alleles. The alleles IA and IB are dominant over i therefore a combination of IA and iproduce blood group A, IB and I produce blood group B. The combination of IA, IB produces blood group AB which has both A and B types of sugar, because of co-dominance. The combination of IA and IA produce blood group A, IB and IB produce B blood group.
The type of blood group produced by the different combinations is shown in the table below:
Short Answer TypeIn a cross between two tall pea plants some of the off-springs produced were dwarf. Show with the help of Punnett square how this is possible.
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