Class 10 heredity-evolution Reproduction DNA replication

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Heredity

Reproduction involves the production of individuals which appear similar to their parents. The similarity in body design among individuals of successive generations is the hallmark of the reproductive process. The similarity in body design is attained because of the passing of a set of characters from one generation to the next generation. In simple terms; heredity can be defined as the passing of traits from parents to offspring. In more technical terms; heredity is defined as the passing of phenotypic traits from parents to offspring. This happens in the case of asexual reproduction as well as in the case of sexual reproduction. In fact, the process of heredity obeys certain rules because of which the set of characters is reliably inherited to the next generation.

 Rules of Inheritance of traits

Inheritance of traits follows certain rules. In the case of sexual reproduction, a progeny gets characters from two parents. But it is not necessary that all the traits from both parents shall be apparent in the progeny. For example; a girl gets traits from her mother as well as her father. Her nose may resemble the nose of her father, while her lips may resemble the lips of her mother. It can be another way around as well. We need to understand how does this happen. You may have seen that child of tall parents may be of average height or child of medium height parents may be considerably taller. Let us try to understand the rules which govern the inheritance of traits in successive generations.

Mendel’s Contribution

Mendel did extensive research on pea plants to understand the patterns of inheritance. He tested about 29,000 pea plants between 1856 and 1863 and came with interesting findings and revelations. For his study, Mendel selected seven traits of pea plants which are as follows:

seed shape, flower colour, seed coat tint, pod shape, unripe pod colour, flower location, and plant height.

Based on his observations, Mendel proposed his laws of inheritance which are also known as Laws of Mendelian Inheritance.

Gregor Johann Mendel (1822 – 1844): Mendel was an Austrian and was born in a farmer family. After completing his studies at the University of Vienna, he joined as a monk. While serving as a priest, Mendel continued his experiments on pea plants. Although Mendel carried extensive research and gave new knowledge on inheritance; his work was rejected by the scientific community and remained unnoticed till his death. It was during the early 20th century that the scientists’ fraternity recognised Mendel’s work. Hugo de Vries and Carl Correns; who worked on the same subject were the scientists to give recognition to Mendel’s work.


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