One of the following statements is not true of viruses

Explanation

Viruses are tiny infectious agents that can only reproduce inside living cells. They are not cells themselves but are composed of genetic material (either DNA or RNA) surrounded by a protein coat. The given question asks us to identify the statement that is not true of viruses. Option A states that viruses are micro-organisms. This statement is true. Although viruses are not cells, they are still considered micro-organisms because they are living entities that can cause disease. Option B states that viruses are smaller than bacteria. This statement is also true. Viruses are much smaller than bacteria and are only visible under an electron microscope. Option C states that viruses can be seen with an ordinary light microscope. This statement is not true, which makes it the correct answer to the question. Viruses are too small to be seen with an ordinary light microscope and require an electron microscope for visualization. Option D lists some diseases caused by viruses, and this statement is true. Viruses can cause many different types of diseases, including tobacco disease, polio, and smallpox. In summary, the correct answer to this question is Option C: viruses cannot be seen with an ordinary light microscope. This is because viruses are much smaller than bacteria and can only be visualized using an electron microscope.