Question

Given below are two statements: 
• [Statement (I):] Tobacco mosaic virus is a rod shaped virus that contains RNA as nucleic acid. 
• [Statement (II):] RNA in the tobacco mosaic virus is double stranded. 
In light of the above statements, choose the most appropriate answer from the options given below. 
 

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Remember that TMV was the very first virus to be discovered (by Dmitri Ivanovsky in 1892) and the first to be crystallized (by Wendell Stanley in 1935), which earned Stanley a Nobel Prize.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Tobacco Mosaic Virus (TMV) is an economically important plant pathogen that infects a wide range of plants, especially tobacco and other members of the family Solanaceae.
It is one of the most thoroughly characterized model systems in the history of virology.

Step 3: Detailed Explanation:
Let us evaluate the two statements regarding TMV:
- Statement (I) is correct: Under electron microscopy, TMV displays a rigid, rod-like morphology.
The virus particles measure approximately 300 nm in length and 18 nm in diameter.
It is composed of a helical capsid made of 2,130 identical coat protein subunits surrounding a single core of genomic ribonucleic acid (RNA).
- Statement (II) is incorrect: The genomic material of TMV is a single-stranded, positive-sense RNA molecule (\(+ssRNA\)), not double-stranded.
This linear single strand consists of approximately 6,400 nucleotides.
It functions directly as mRNA inside host cells, utilizing the host's translation machinery to synthesize viral proteins immediately upon infection.
Therefore, Statement (I) is correct, but Statement (II) is incorrect.

Step 4: Final Answer:
Statement (I) is correct but Statement (II) is incorrect, matching Option (C).