State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.
Law of Independent Assortment (Third law) is based on inheritance of two genes, i.e. dihybrid cross which states that when two pairs of contrasting traits are combined in a hybrid, segregation of one pair of characters is independent of the other pair of characters. These factors randomly rearrange in the offspring producing both parental and new combination of characters means inheritance of one character does not affect the inheritance of another character and both characters
assort independently. The Punnett square can be used to understand the independent segregation of the two pairs of genes during meiosis. Linkage is the exception of law of independent assortment.
(a) Arrange the following hormones in the sequence of their secretion in a pregnant woman.
(b) Mention their source and the function they perform.
Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident’s Welfare Association of your locality organised an awareness programme entitled ‘Bury not burn’. They invited you, being a biology student to participate.
(a) How would you justify your arguments that promote burying and discourage burning?
(Give two reasons)
(b) With the help of flow charts, one for each practice, depict the chain of events that follow.
Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.
