(a) What is polygenic inheritance ? Explain with the help of a suitable example.
(b) How are pleiotropy and Mendelian pattern of inheritance different from polygenic pattern of inheritance ?
Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross.
A. Why is haemophilia generally observed in human males? Explain the conditions under which a human female can be haemophilic.
B. A pregnant human female was advised to undergo M.T.P. It was diagnosed by her doctor that the foetus she is carrying has developed from a zygote formed by an XX egg fertilized by Y-carrying sperm. Why was she advised to undergo M.T.P.?
During a medical investigation, an infant was found to possess an extra chromosome 21. Decribe the symptoms the child is likely to develop later in the life.
An additional copy of chromosome number 21 (trisomy of chromosome number 21) in humans results in Down’s syndrome.Following characteristic symptoms are likely to develop in the child due to the above mentioned conditions:
(i) Short statured with small, round head.
(ii) Furrowed tongue and partially open mouth.
(iii) Broad palm with characteristics palm crease.
(iv) Slow mental, physical and psychomotor development.
State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.
Give a scientific term:
Exhibition of superiorityof the hybrid over both of its parents