Microbiology Chapter on Soil Bacteria

Multiple Choice Questions

• Question 1: Approximately 20% of soil bacterial population, using viability-based methods, is detectable as compared to microscopic counts..
• Question 2: Approximately 1000 species of microorganisms exist in a gram of typical, fertile soil.
• Question 3: Eubacteria is not one of the three domains of life.
• Question 4: Total bacterial numbers generally decrease with depth in the soil.
• Question 5: The Limnetic zone is the surface layer of open water where light reaches the bottom.
• Question 6: Texture is defined as the percentage of sand, silt, and clay in a soil.
• Question 7: Gram-negative bacteria have two membranes in their cell envelope.
• Question 8: A selective growth medium only allows the growth of specific organisms.

Short Answer Questions

• Question 20: Bacteria have the greatest number in surface soils, while fungi have the greatest biomass.
• Question 21: Rhizosphere is the zone of soil influenced by plant roots.
• Question 22: Rhizoplane is the root surface and its adhering soil.
• Question 23: Plasmids often carry genes for antibiotic resistance, nitrogen fixation, and heavy metal resistance.
• Question 24: Fungi decompose organic matter, protozoa regulate bacterial populations via predation, macrofauna generate soil and decompose organic matter.

Additional Questions

• Question 25: Soil aggregates form with microorganisms (fungi and bacteria) binding soil particles with their extracellular polymers. Fungal hyphae, bacterial EPS (exopolysaccharides), and plant roots contribute. Organic matter and glomalin (from mycorrhizal fungi) also help stabilize aggregates.
• Question 26: Soil structure impacts the soil atmosphere's gas composition. Well-aerated soils have higher oxygen (O2) and lower carbon dioxide (CO2). Compact/waterlogged soils limit oxygen diffusion, leading to anaerobic respiration and methane (CH4) production.
• Question 27: Primary productivity in aquatic systems is performed by phytoplankton (algae and cyanobacteria) via photosynthesis. Secondary productivity is performed by heterotrophic bacteria that consume organic material.
• Question 28: An example of microbial adaptation in extreme environments is thermophiles (Archaea) using heat-stable enzymes like DNA polymerase in hot springs.

Matching Questions

• Question 29: Matching questions provide different organisms or characteristics to match. (Specific details are omitted, following user instructions).
• Question 30: This question matches types of nutrition with their respective carbon and energy sources to obtain sustenance..
• Question 31: This question pairs scientists with their significant scientific discoveries or contributions. (Specific details are omitted, following user instructions).
• Question 32: This question categorizes microogranisms as prokaryotic, eukaryotic, or neither. (Specific details are omitted, following user instructions).
• Question 33: This question associates various terms with numerical values. (Specific details are omitted, following user instructions).
• Question 34: This ranks biological entities by their relative size (Specific details are omitted, following user instructions).

True/False Questions

• Question 36: Antibiotic resistance commonly occurs in soil microorganisms. (True)
• Question 37: Cation exchange capacity (CEC) of organic matter is fixed and doesn't vary with changes in environmental pH. (False)
• Question 38: Most fungi in typical soils are chemoheterotrophs. (True)
• Question 39: Plant root biomass generally exceeds fungal biomass in soil. (False)
• Question 40: Culture-independent methods typically detect a wider diversity of soil bacteria than culture-dependent methods. (True)

Bonus Questions

• Question 41: Ribosomal RNA genes (e.g., 16S rRNA) are the favored sequencing targets for identifying bacteria because they are conserved, universal, and contain variable regions combined with conserved ones, aiding bacterial classification.
• Question 42: A serial dilution method systematically dilutes a soil sample and then plates onto media to count the bacterial numbers by determining the colony forming units.

Este quiz explora le diversitate de bacterias in terra e lor interacciones con le medio ambiant. Interrogaiones inclue informationes super le microflora del terra e zonas aquaticas. Testa tu cognoscentia sobre le traiectos de las microbiotas et biogeochimica!