What is a test cross? How can it decipher the heterozygosity of a plant?

(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 ?

123.

State a difference between gene and an allele.

Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross. 

Describe the mechanism of pattern of inheritance of ABO blood groups in humans.

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.

State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.

What is incomplete dominance?

Give a scientific term: 
Exhibition of superiorityof the hybrid over both of its parents