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Microbiology: Microbial Ecology and Pathogenesis Flashcards

7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Microbiology: Microbial Ecology and Pathogenesis flashcards as text

  1. The ID₅₀ (infectious dose for 50% of a population) is used to measure which property of a pathogen?

    Answer: Virulence

    Virulence is quantified by measures like ID₅₀ or LD₅₀, indicating how potent a pathogen is at causing infection or death.

  2. Which type of symbiosis is demonstrated by Rhizobium bacteria living in legume root nodules and fixing nitrogen for the plant?

    Answer: Mutualism

    Rhizobium fixes nitrogen for the plant while receiving organic carbon in return, a classic mutualistic (both benefit) relationship.

  3. Microbial mats found in hot springs are ecologically significant because they:

    Answer: Demonstrate stratified communities with different metabolic guilds

    Microbial mats are layered communities where each stratum contains organisms with distinct metabolisms (phototrophs, heterotrophs, anaerobes) adapted to local conditions.

  4. A toxin that acts by inhibiting protein synthesis in eukaryotic cells (like diphtheria toxin) would be classified as a:

    Answer: Cytotoxin

    Diphtheria toxin is a cytotoxin that ADP-ribosylates EF-2 (elongation factor 2), halting eukaryotic protein synthesis and killing host cells.

  5. Which of the following describes 'colonization' in the context of infectious disease?

    Answer: The pathogen is present and multiplying without causing disease

    Colonization occurs when a microorganism establishes itself on or in a host and multiplies, but without producing signs or symptoms of disease.

  6. Bacteriophages contribute to microbial ecology primarily through:

    Answer: Regulating bacterial population sizes and driving horizontal gene transfer

    Phages kill bacteria (top-down control) and facilitate transduction, shaping community structure and spreading virulence genes across populations.

  7. Which step in the chain of infection refers to the route by which a pathogen leaves its reservoir?

    Answer: Portal of exit

    The portal of exit is the route through which a pathogen leaves the reservoir host, such as respiratory droplets, feces, or blood.