Nutrient Cycling MCQs (Quiz 11) Posted on May 30, 2026Author agropublishers 0 1. Which environmental factor has the greatest influence on weathering rates? Magnetic field strength Climate Longitude Population density 2. A plant growing in phosphorus-poor soil still thrives because of a fungal partner that extends far into the soil to absorb nutrients on its behalf. What is this fungal partner called __________________ Azotobacter Mycorrhizal fungi Nitrosomonas Rhizobium 3. An increase in atmospheric CO₂ enhances the greenhouse effect because CO₂ ________________ Converts oxygen into ozone Absorbs and re-emits outgoing infrared radiation Reflects all incoming solar radiation Prevents evaporation from oceans 4. Which of the following correctly describes the role of nitrogen fixation in the nitrogen cycle? It oxidizes ammonium ions into nitrites and nitrates for plant uptake It breaks down proteins in dead organisms into ammonium ions It reduces atmospheric N₂ into ammonia, making nitrogen available to living organisms It converts nitrates into nitrogen gas, returning it to the atmosphere 5. The weathering of rocks contributes directly to ___________________ Formation of humus Atmospheric circulation Soil formation and nutrient release Development of food chains 6. Which of the following correctly describes denitrification? Conversion of atmospheric N₂ into ammonia by soil bacteria Breakdown of proteins into ammonium ions by decomposers Oxidation of ammonium ions into nitrites and nitrates Reduction of nitrates into nitrogen gas by anaerobic bacteria 7. Which mineral dissolves most readily in pure water? Feldspar Mica Quartz Halite 8. A tropical rainforest has a very high nutrient turnover rate despite having nutrient-poor soil. What best explains this? Slow decomposition allows gradual accumulation of nutrients in the soil Frequent rainfall dissolves rock minerals, replenishing soil nutrients rapidly Nutrients are imported constantly from surrounding ecosystems via rivers Rapid decomposition and immediate uptake by plant roots recycle nutrients so efficiently that little accumulates in the soil 9. Which gas released during decomposition of organic matter in waterlogged soils is a potent greenhouse gas? Carbon dioxide (CO₂) Methane (CH₄) Oxygen gas (O₂) Nitrogen gas (N₂) 10. A plant growing in nitrate-rich soil absorbs NO₃⁻ through its roots. Which sequence correctly represents what happens during assimilation? NO₃⁻ is converted to N₂ and expelled through stomata NO₃⁻ is reduced and incorporated into organic molecules such as amino acids, proteins, and nucleic acids NO₃⁻ is broken down into CO₂ and water during respiration NO₃⁻ is released back into the soil after absorption Loading … Question 1 of 10
