Nutrient Cycling MCQs (Quiz 11)

1. A tropical rainforest has a very high nutrient turnover rate despite having nutrient-poor soil. What best explains this?

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

Slow decomposition allows gradual accumulation of nutrients in the soil

2. Which environmental factor has the greatest influence on weathering rates?

Longitude

Magnetic field strength

Climate

Population density

3. 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

4. Which of the following correctly describes the role of nitrogen fixation in the nitrogen cycle?

It converts nitrates into nitrogen gas, returning it to the atmosphere

It breaks down proteins in dead organisms into ammonium ions

It reduces atmospheric N₂ into ammonia, making nitrogen available to living organisms

It oxidizes ammonium ions into nitrites and nitrates for plant uptake

5. Which of the following correctly describes denitrification?

Conversion of atmospheric N₂ into ammonia by soil bacteria

Breakdown of proteins into ammonium ions by decomposers

Reduction of nitrates into nitrogen gas by anaerobic bacteria

Oxidation of ammonium ions into nitrites and nitrates

6. 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 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

7. The weathering of rocks contributes directly to ___________________

Soil formation and nutrient release

Development of food chains

Atmospheric circulation

Formation of humus

8. 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)

9. 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

10. Which mineral dissolves most readily in pure water?

Feldspar

Mica

Halite

Quartz

Question 1 of 10

Nutrient Cycling MCQs (Quiz 11)

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