Nutrient Cycling MCQs (Quiz 9)

1. Which essential plant nutrient is commonly released through weathering of feldspar minerals?

Potassium

Sulfur

Phosphorus

Nitrogen

2. Which organism is often the first colonizer of bare rock surfaces?

Grass

Lichens

Shrubs

Trees

3. When a leaf falls to the forest floor and fungi and bacteria break it down, what is the key outcome for the ecosystem?

New organic proteins are synthesized and passed to herbivores

Solar energy trapped in the leaf is converted into heat permanently

Carbon dioxide is absorbed from the atmosphere into the leaf material

Nutrients locked in the dead leaf are released as inorganic ions, making them available to plants again

4. When soil microorganisms take up mineral nutrients and lock them into their own body tissues, making them temporarily unavailable to plants, this is called ________________

Assimilation

Nutrient immobilization

Denitrification

Leaching

5. Two groups of bacteria are involved in nitrification. Which pair correctly performs the two oxidation steps?

Nitrosomonas converts NH₄⁺ to NO₂⁻; Nitrobacter converts NO₂⁻ to NO₃⁻

Nitrobacter converts NH₄⁺ to NO₂⁻; Nitrosomonas converts NO₂⁻ to NO₃⁻

Rhizobium converts NH₄⁺ to NO₂⁻; Pseudomonas converts NO₂⁻ to NO₃⁻

Azotobacter converts NH₄⁺ to NO₂⁻; Rhizobium converts NO₂⁻ to NO₃⁻

6. Acid rain mainly affects structures made of ___________________

Limestone and marble

Sandstone and shale

Granite and quartzite

Basalt and gabbro

7. Which of the following processes represents assimilation in the nitrogen cycle?

Anaerobic bacteria reducing nitrates into nitrogen gas

Decomposers breaking down dead organic matter into ammonium ions

Plants absorbing nitrate ions and incorporating them into amino acids and proteins

Bacteria converting ammonia into nitrites in the soil

8. Which weathering agent is most responsible for forming rounded river pebbles?

Carbon dioxide

Oxygen

Plant roots

Flowing water and abrasion

9. When forests are burned, carbon stored in biomass is primarily released as ________________

Carbon dioxide

Oxygen gas

Methane

Nitrogen gas

10. Why is the phosphorus cycle described as sedimentary rather than gaseous, unlike the carbon and nitrogen cycles?

Phosphorus has no stable gaseous form under normal conditions, so it cycles mainly through rocks, soil, water, and living organisms

Ocean currents prevent phosphorus from entering the atmosphere

Living organisms convert all available phosphorus into organic compounds permanently

Phosphorus reacts with oxygen in the atmosphere and is rapidly destroyed

Question 1 of 10

Nutrient Cycling MCQs (Quiz 9)

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