Nutrient Cycling MCQs (Quiz 9)

1. Acid rain mainly affects structures made of ___________________

Limestone and marble

Granite and quartzite

Sandstone and shale

Basalt and gabbro

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

Oxygen

Plant roots

Flowing water and abrasion

Carbon dioxide

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

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

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

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

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

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

Potassium

Nitrogen

Phosphorus

Sulfur

5. 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

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

Solar energy trapped in the leaf is converted into heat permanently

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

Nitrogen gas

Carbon dioxide

Methane

Oxygen gas

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

Living organisms convert all available phosphorus into organic compounds permanently

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

Phosphorus reacts with oxygen in the atmosphere and is rapidly destroyed

Ocean currents prevent phosphorus from entering the atmosphere

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

Trees

Shrubs

Grass

Lichens

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

Nutrient immobilization

Denitrification

Leaching

Assimilation

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

Anaerobic bacteria reducing nitrates into nitrogen gas

Bacteria converting ammonia into nitrites in the soil

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

Decomposers breaking down dead organic matter into ammonium ions

Question 1 of 10

Nutrient Cycling MCQs (Quiz 9)

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