What is the term for a mutually beneficial relationship between a microorganism and its host?
In mutualism, both the microorganism and the host benefit from the relationship. For example, gut bacteria aid in digestion and nutrient absorption while benefiting from a stable environment and nutrients.
Which of the following is a key factor in microbial pathogenicity?
Virulence factors, such as toxins, enzymes, and surface proteins, enable pathogens to invade hosts, evade immune defenses, and cause disease. Endospores aid survival, not pathogenicity, and ribosomes are common to all cells.
What role do microbes play in nitrogen cycling in the environment?
Certain microbes, such as nitrogen-fixing bacteria, convert atmospheric nitrogen (N₂) into forms like ammonia (NH₃) that plants can use. This process is critical for the nitrogen cycle and ecosystem sustainability.
Which microorganism is most likely to cause an opportunistic infection?
Opportunistic infections occur when a normally harmless microorganism causes disease due to a weakened immune system or a breach in barriers. Candida albicans, a yeast, often becomes pathogenic in immunocompromised hosts.
What is the first line of defense against microbial pathogens in the human body?
The skin and mucous membranes form a physical barrier that prevents microbial entry. Antibodies and white blood cells are part of the adaptive and innate immune responses, while fever is a systemic defense mechanism.