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