Question

Which disease is caused by a virus?

• A. Common cold
• B. Typhoid
• C. Malaria
• D. Pneumonia

Hint:

Common Cold \(\rightarrow\) Virus, Typhoid \(\rightarrow\) Bacteria, Malaria \(\rightarrow\) Protozoa. This comparison is frequently asked in examinations.

Answer 1

The Correct Option is A

Concept: Diseases can be caused by different pathogens such as viruses, bacteria, protozoa, fungi, and helminths. Identifying the causative organism is important in biology as well as medicine. Viruses are acellular infectious particles that can reproduce only inside living host cells.

Step 1: Examine each option. Common Cold The common cold is generally caused by Rhinoviruses and sometimes by Coronaviruses. Therefore, it is a viral disease. Typhoid Typhoid is caused by the bacterium \[ Salmonella\ typhi \] Hence it is a bacterial disease. Malaria Malaria is caused by \[ Plasmodium \] which is a protozoan parasite. Pneumonia Pneumonia is commonly caused by bacteria such as \[ Streptococcus\ pneumoniae \] although some viral forms also exist. In standard NCERT-based MCQs, pneumonia is classified as a bacterial disease.

Step 2: Select the viral disease. Among all the options, only common cold is primarily viral. \[ \boxed{\text{Common Cold}} \] Hence, the correct answer is \[ \boxed{(1)\ \text{Common Cold}} \]