Phosphorus cycle Knowledge-Based Download PDF

Questions

1. 1.

   Which biological process facilitates the transfer of phosphorus from marine food webs back to terrestrial ecosystems over ecological timescales?

   • A) Deposition of guano by fish-eating seabirds
   • B) Microbial volatilization of marine phosphate into the atmosphere
   • C) Direct uptake of benthic oceanic phosphate by coastal plant roots
   • D) Biological fixation of dissolved phosphate by salt marsh grasses
2. 2.

   Over long geological timescales, phosphorus that has been deposited in deep ocean sediments primarily re-enters terrestrial ecosystems through which mechanism?

   • A) Atmospheric precipitation following gas-phase photochemical reactions
   • B) Direct biological transport by migratory pelagic fish species
   • C) Tectonic uplift of marine sedimentary rock followed by weathering
   • D) Chemosynthetic oxidation by deep-sea hydrothermal vent bacteria
3. 3.

   In terrestrial ecosystems, plants assimilate dissolved inorganic phosphate from the soil primarily to synthesize which group of essential biomolecules?

   • A) Nucleic acids, phospholipids, and ATP
   • B) Cellulose, starch, and glycogen
   • C) Triglycerides, steroid hormones, and waxes
   • D) Polypeptides, fibrous proteins, and collagen
4. 4.

   Which process is primarily responsible for releasing inorganic phosphate from geological reservoirs into soil and aquatic environments, making it available to living organisms?

   • A) Microbial fixation of phosphorus from deep subsoil gas pockets
   • B) Condensation and precipitation of airborne volcanic emissions
   • C) Weathering and leaching of phosphate-bearing sedimentary rocks
   • D) Biological assimilation of atmospheric particulate matter by lichens
5. 5.

   Which of the following characteristics best distinguishes the phosphorus cycle from other major biogeochemical cycles, such as the carbon and nitrogen cycles?

   • A) Phosphorus moves between trophic levels solely through mutualistic fungal partners without ever dissolving in soil water.
   • B) Gaseous atmospheric compounds serve as the primary global reservoir from which terrestrial autotrophs absorb phosphorus.
   • C) It lacks a significant atmospheric reservoir, cycling predominantly through the lithosphere, hydrosphere, and biosphere.
   • D) Volcanic emissions and lightning fixation provide the main inputs of bioavailable phosphate into terrestrial ecosystems.