Which of the following is a pathogen?

• A. Bacteria
• B. Mycotoxins
• C. Algal
• D. Plant

Answer: (A)

A pathogen is an agent that causes disease in a host. Bacteria are living microorganisms that can invade tissues, multiply, and trigger disease in humans and other organisms, making them classic disease-causing agents. Many well-known diseases are caused by bacteria, such as strep throat or tuberculosis.

Mycotoxins are toxic compounds produced by fungi, so they act as poisons rather than infectious agents themselves. Fungi can be pathogens in some contexts, but the toxins they produce aren’t pathogens. Algae can produce harmful effects, especially in aquatic environments, but they aren’t typically described as pathogens. Plants are hosts in disease interactions rather than infectious agents.