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
The human gut microbiome primarily contributes to host health by:
Answer: Competing with pathogens, synthesizing vitamins, and training the immune system
The gut microbiome protects against colonization by pathogens, synthesizes vitamins (e.g., K and B₁₂), and shapes immune development.
Which of the following is an example of amensalism in microbial ecology?
Answer: Penicillium mold secreting penicillin that inhibits bacterial growth
Amensalism occurs when one organism is harmed by another that is unaffected; Penicillium kills bacteria while gaining nothing from the interaction.
A superantigen, such as staphylococcal toxic shock syndrome toxin-1 (TSST-1), causes disease by:
Answer: Non-specifically activating large numbers of T cells, causing cytokine storm
Superantigens crosslink MHC II and T-cell receptors non-specifically, activating up to 20% of all T cells and triggering a massive, damaging cytokine release.
In marine ecosystems, the 'microbial loop' describes:
Answer: The recycling of dissolved organic matter by bacteria back into the food web
The microbial loop channels dissolved organic carbon through bacteria, which are then consumed by protists, re-entering the classical food chain.
Which virulence factor do many pathogenic bacteria use to acquire iron from host cells, an essential nutrient for bacterial growth?
Answer: Siderophores
Siderophores are high-affinity iron-chelating molecules secreted by bacteria to scavenge iron from host proteins like transferrin and lactoferrin.
Transduction, as a mechanism of horizontal gene transfer, involves:
Answer: Transfer of DNA from one bacterium to another via a bacteriophage
In transduction, a bacteriophage accidentally packages bacterial DNA and delivers it to a new host cell upon infection.
Which of the following best explains why antibiotic-resistant genes spread so rapidly through bacterial populations in a hospital environment?
Answer: Horizontal gene transfer via plasmids, combined with antibiotic selection pressure, accelerates resistance spread
Resistance plasmids can transfer between unrelated bacterial species through conjugation, and antibiotics kill susceptible competitors, giving resistant strains a strong selective advantage.