Role of microbes (decomposers, human microbiome) Knowledge-Based Download PDF

Questions

1. 1.

   How do resident microorganisms of the human skin microbiome contribute to preventing the colonization of harmful transient pathogens on the epidermal surface?

   • A) By synthesizing keratin filaments that fortify the structural integrity of the stratum corneum
   • B) By producing melanin granules that absorb ultraviolet radiation within epithelial tissues
   • C) By secreting digestive enzymes that directly degrade the host's underlying basement membrane
   • D) By breaking down sebum into free fatty acids that generate an acidic barrier unfavorable to pathogenic microbes
2. 2.

   By which mechanism do microbial decomposers, such as saprotrophic bacteria and fungi, obtain nutrients from complex organic detritus?

   • A) They engulf solid organic particles through phagocytosis and digest them intracellularly within lysosomes.
   • B) They oxidize gaseous inorganic carbon into simple sugars via chemosynthesis to degrade the surrounding detritus.
   • C) They transport intact macromolecules directly across membrane channels for internal cytoplasmic hydrolysis.
   • D) They secrete extracellular enzymes into the environment to break down insoluble polymers into absorbable soluble monomers.
3. 3.

   How does the resident human microbiota primarily provide colonization resistance against opportunistic pathogens?

   • A) By directly phagocytosing invasive microbial cells and activating cellular immunity
   • B) By competing for available nutrients and attachment sites while producing inhibitory metabolites
   • C) By inducing widespread host tissue inflammation that sterilizes mucous membranes
   • D) By permanently altering host genomic sequences to synthesize pathogen-specific antibodies
4. 4.

   Which statement correctly describes the fundamental ecological role played by microbial decomposers within an ecosystem?

   • A) They fix gaseous carbon dioxide into carbohydrates through oxygenic photosynthesis to initiate trophic energy transfer.
   • B) They feed directly on living plant tissue to control producer biomass and reduce canopy density.
   • C) They secrete extracellular enzymes to break down dead organic matter, recycling essential inorganic nutrients back into the soil and atmosphere.
   • D) They absorb ambient geothermal heat to synthesize complex organic biomolecules from unbonded elemental minerals.
5. 5.

   Which of the following statements correctly identifies a vital physiological function of the bacterial microbiome inhabiting the human large intestine?

   • A) They secrete hydrolytic enzymes that break down inorganic minerals into absorbable elemental ions.
   • B) They synthesize essential micronutrients such as vitamin K and help inhibit the establishment of pathogenic species.
   • C) They generate molecular oxygen through anaerobic metabolism to maintain aerobic respiration in enterocytes.
   • D) They degrade host epithelial tight junctions to ensure continuous leukocyte recruitment and systemic inflammation.