Nutrient Cycling MCQs (Quiz 6) Posted on May 30, 2026Author agropublishers 0 1. Burning fossil fuels releases large amounts of __________________ gas, directly contributing to the greenhouse effect and global warming Nitrogen gas (N₂) Carbon dioxide (CO₂) Water vapor (H₂O) Oxygen gas (O₂) 2. When a plant absorbs nitrates from the soil and uses them to build proteins, this is an example of ____________ Denitrification Assimilation Decomposition Excretion 3. Lichens contribute to weathering by ______________________ Removing oxygen from rocks Increasing atmospheric pressure Producing organic acids that dissolve minerals Producing volcanic heat 4. Which weathering process directly releases calcium and magnesium ions into soil solution, making them available for plant uptake? Frost wedging Exfoliation Carbonation Thermal expansion 5. Plants mainly absorb water and mineral ions from the soil through their _________________ Root hair cells Stomata Leaves Stem vessels 6. Which ecosystem acts as one of the largest natural carbon sinks on Earth? Oceans Agricultural fields Deserts Urban ecosystems 7. The breakdown of rocks into soil particles is an important consequence of _____________ Weathering processes Volcanic eruptions Plate tectonics Ocean circulation 8. What is the correct sequence of products formed during nitrification? NH₃ → N₂ → NO₃⁻ NH₄⁺ → NO₂⁻ → NO₃⁻ N₂ → NH₃ → NO₂⁻ NO₃⁻ → NO₂⁻ → NH₄⁺ 9. Which of the following is NOT an agent of nitrogen fixation? Mycorrhizal fungi Cyanobacteria Lightning Bacteria associated with legume roots 10. Which type of weathering is most dominant in tropical rainforests? Glacial weathering Physical weathering Chemical weathering Frost weathering Loading … Question 1 of 10
