Question

why DNA is called hereditary material

Answer 1

Because “heredity” is defined as: “the passing on of physical or mental characteristics genetically from one generation to another.”

“hereditary” is something that is passed on from parent to offspring, or from a cell to the two new daughter cells during cell division.

DNA contains genetic material and we get our genetic material passed on from your parents. We get half of our genetic material from our mother, half from our father. We genetic material is inherited from your ancestors.
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Answer 2

Answer:

Scientists dealing in molecular biology proved with the help of experiments that DNA is a hereditory material. There are two main evidences viz – (A) Griffith’s experiment: It was done in 1928 by Frederick Griffith. It was one of the experiment showing that bacteria can get DNA through a process called transformation. He used two strains of bacteria, called Diplococcus pheumonae viz. – type II-R (rough or non virulent) and type III – S (Smooth or virulent). These bacteria infect rats & human beings. The strain III- S is pathogenic and the strain II – R is non- pathogenic. The strain III- S covers itself with a polysaccharide capsule that protects it form the host immune system. This means that the host cell will die. The strain II-R does not have the protective capsule and it is killed by the host immune system. In this experiment, the bacteria of strain III – S were killed by heat and their remains were added to strain II-R bacteria. The killed strain III-S and strain II-R harmed the mice but the blend of the two was able to kill mice. Griffith was also able to get both live II-R and III- S strains from the blood of these dead mice. He concluded that the type II-R had been transformed into the lethal III- S strain by transforming principle. Griffith observed- Strain III- S, when injected kill the mice. Strain II- R, when injected, the mice remained live (unaffected). Killed strain III- S when injected, the mice remained live (unaffected). When both the killed strain S – III and strain II – R were injected, they killed the mice. Griffith concluded that while the bacteria of strain III-R had been killed, the DNA had survived the heating process and was taken up by the strain II-R. Armed with DNA of strain III-S, the bacteria of strain II-R developed the capsule and get protected from the host’s immune system and could kill the mice.

Explanation:

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