NEET Test Series from KOTA - 10 Papers In MS WORD
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BIOLOGICAL CLASSIFICATION(NCERT)
285874
In some viruses, RNA is present instead of DNA indicating that
1 their nucleic acid must combine with host DNA before replication.
2 they cannot replicate.
3 there is no hereditary information.
4 RNA can transfer heredity material.
Explanation:
(d) Viruses are defined as infectious nucleoproteins. A complete virus particle is called virion whose main function is to deliver its DNA or RNA gesnome into the host cell, so that genome can be expressed by the host cell. In a particular virus either DNA or RNA is genetic material, never both are present in a virus. Hence, viruses are:
(i) Double stranded DNA or ds DNA - Hepatitis B
(ii) Single stranded DNA or ss DNA - coliphage
(iii) Double stranded RNA or.ds RNA - Reo virus, wound Tumor virus
(iv) Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV)