Important Questions for Class 12 Chapter 5 - Principles of Inheritance and Variation

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Important questions based on NCERT syllabus for Chapter 5 - Principles of Inheritance and Variation:

Question-1: Briefly mention the contribution of T.H. Morgan in genetics.

Solution: Thomas Hunt Morgan (1866-1945) is called father of experimental genetics. He was an American scientists, famous for his experimental research with the fruit fly (Drosophila) by which he established the chromosome theory of heredity. He discovered presence of gene over chromosomes, chromosome theory of linkage, chromosome mapping, crossing over, criss-cross inheritance & mutability of genes. Morgan’s work played a key role in establishing the field of genetics. He received the nobel prize for physiology or Medicine in 1933.

Question-2: What is pedigree analysis? Suggest how such an analysis, can be useful.

Solution: Pedigree analysis is study of pedigree for the transmission of particular trait and finding the possibility of absence or presence of that trait in homozygous or heterozygous state in a particular individual. Pedigree analysis helps-
(i)in analysis of transmission of character in family over generation.
(ii)in genetic counselling of disease like haemophilia.
(iii)to identify whether a particular genetic disease is due to recessive gene or a dominant gene.
(iv) to identify the possible origin of the defective gene in the family or in a population.

Question-3: Who had proposed the chromosomal theory of the inheritance?

Solution: Sutton and Boveri proposed the chromosomal theory of the inheritance. The theory believes that chromosomes are vehicles of hereditary information possess mendelian factors or genes and it is the chromosomes which segregate and assort independently during transmission from one generation to the next.