NHA Clinical Patient Care Practice Test 2025 – 400 Free Practice Questions to Pass the Exam

The correct choice, focusing on disease-causing agents, encompasses a variety of microorganisms known to cause illness in humans and other organisms. Viruses, bacteria, fungi, and protozoa are all classified as pathogens when they are involved in disease processes. Each of these types of microorganisms can have different mechanisms of action, transmission, and effects on the host, but they all fall under the umbrella of agents that can lead to infectious diseases.

For instance, viruses require a host cell to replicate and can lead to diseases ranging from the common cold to more severe illnesses like HIV/AIDS. Bacteria can be both beneficial and harmful; pathogenic bacteria can cause infections such as strep throat or tuberculosis. Fungi can lead to conditions like athlete's foot or more systemic infections in immunocompromised individuals. Protozoa, such as those causing malaria, can result in severe health issues.

In contrast, non-infectious agents do not cause disease—they might refer to toxins or chemical exposures. Environmental contaminants could include pollutants that may affect health but are not classified as microorganisms. Allergens are substances that trigger allergic reactions, which are different from infectious diseases caused by pathogens. Understanding these distinctions helps in managing and preventing diseases effectively.