Which of the following statements accurately describe pathogens?

(a) Pathogens are microorganisms, including viruses, bacteria, and fungi, that cause disease in their host organisms.

(b) Pathogens reproduce within the host's body and disrupt normal physiological processes, leading to structural and functional damage.

I and II

Explanation:

(a) Pathogens, which can include viruses, bacteria, and fungi, are microorganisms that have the capability to cause disease in their host organisms. They invade the host's body and can disrupt normal physiological functions, leading to various symptoms and health problems.

(b) Once inside the host, pathogens multiply and interfere with the normal vital activities of the body. They can damage tissues, organs, and systems through various mechanisms, such as releasing toxins, invading cells, or causing an excessive immune response. This disruption can result in morphological (structural) and functional damage, contributing to the development of disease.

Therefore, both statements (a) and (b) correctly describe the nature and impact of pathogens on the host organism.