Which of the following is a characteristic of a pathogen that determines its virulence?

• A. Ability to produce toxins
• B. Presence of a cell wall
• C. Requirement for oxygen
• D. Ability to photosynthesize

Answer: (A)

Verified step by step guidance

1. Understand the concept of virulence: Virulence refers to the degree of pathogenicity or the ability of a microorganism to cause disease in a host.
2. Identify characteristics of pathogens that influence virulence: These include factors that enhance the microorganism's ability to invade the host, evade the immune system, and cause damage.
3. Analyze each option in the context of virulence: For example, the ability to produce toxins directly contributes to the damage caused to host tissues, increasing virulence.
4. Recognize that structural features like the presence of a cell wall or metabolic requirements such as oxygen use do not directly determine virulence, although they may affect survival.
5. Conclude that among the given options, the ability to produce toxins is the characteristic that determines virulence because toxins are molecules that harm the host and facilitate infection.