Nutrient Cycling MCQs (Quiz 11)

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

Climate

Magnetic field strength

Population density

Longitude

2. Which mineral dissolves most readily in pure water?

Quartz

Halite

Mica

Feldspar

3. The weathering of rocks contributes directly to ___________________

Development of food chains

Formation of humus

Soil formation and nutrient release

Atmospheric circulation

4. Which of the following correctly describes denitrification?

Conversion of atmospheric N₂ into ammonia by soil bacteria

Reduction of nitrates into nitrogen gas by anaerobic bacteria

Breakdown of proteins into ammonium ions by decomposers

Oxidation of ammonium ions into nitrites and nitrates

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

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

Frequent rainfall dissolves rock minerals, replenishing soil nutrients rapidly

Nutrients are imported constantly from surrounding ecosystems via rivers

6. 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)

7. 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 released back into the soil after absorption

NO₃⁻ is broken down into CO₂ and water during respiration

NO₃⁻ is reduced and incorporated into organic molecules such as amino acids, proteins, and nucleic acids

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

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

It breaks down proteins in dead organisms into ammonium ions

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

It oxidizes ammonium ions into nitrites and nitrates for plant uptake

9. An increase in atmospheric CO₂ enhances the greenhouse effect because CO₂ ________________

Reflects all incoming solar radiation

Converts oxygen into ozone

Absorbs and re-emits outgoing infrared radiation

Prevents evaporation from oceans

10. 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 __________________

Rhizobium

Nitrosomonas

Azotobacter

Mycorrhizal fungi

Question 1 of 10

Nutrient Cycling MCQs (Quiz 11)

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