Which of the following best describes how exotoxins typically affect host cells?

• A. They integrate into the host genome and alter genetic expression.
• B. They act as nutrients for host cells, promoting cell growth.
• C. They stimulate the host immune system to produce antibodies without causing direct damage.
• D. They disrupt specific cellular functions by targeting enzymes or cell membranes.

Answer: (D)

Verified step by step guidance

1. Understand what exotoxins are: Exotoxins are toxic proteins secreted by certain bacteria that can cause damage to the host by interfering with normal cellular functions.
2. Recognize the mechanism of action of exotoxins: They typically target specific components of host cells, such as enzymes or cell membranes, disrupting normal cellular processes.
3. Eliminate incorrect options by comparing their descriptions to known exotoxin behavior: For example, exotoxins do not integrate into the host genome, nor do they serve as nutrients or merely stimulate antibody production without causing damage.
4. Focus on the key phrase that exotoxins 'disrupt specific cellular functions' by targeting enzymes or membranes, which aligns with their known biochemical activity.
5. Conclude that the best description of exotoxin action is that they disrupt specific cellular functions by targeting enzymes or cell membranes, causing damage to the host.