Nutrient Cycling MCQs (Quiz 10)

1. A peat bog stores large amounts of carbon accumulated over thousands of years. When drained and burned, it releases CO₂ into the atmosphere. In this scenario, the peat bog has changed its role to _____________________________

A recycler, as it is returning carbon to the soil

A decomposer, as it is breaking down organic matter

A nutrient source, as it is now releasing stored carbon into the environment

A nutrient sink, as it is absorbing more carbon

2. Which rock characteristic most strongly affects weathering susceptibility?

Mineral composition

Rock color

Rock location

Rock age alone

3. Organic nitrogen in waterlogged soil is converted into _______ during ammonification

Ammonium ions, because oxygen is absent and nitrification cannot occur

Nitrate ions, because nitrifying bacteria are active without oxygen

Nitrite ions, because nitrogen is partially oxidized in anaerobic soils

Nitrogen gas, because ammonification directly releases gaseous nitrogen

4. Which of the following best represents a nutrient budget in an ecosystem?

The speed at which plants absorb minerals from the soil

The number of trophic levels through which nutrients pass

The cost of adding fertilizers to agricultural land

The total amount of nutrients entering, leaving, and being stored in an ecosystem

5. The rate of weathering generally increases with ____________________

Increasing temperature and moisture

Decreasing temperature

Decreasing moisture

Increasing rock size

6. Why is atmospheric CO₂ increasing despite the presence of natural carbon sinks?

Human emissions exceed the capacity of natural sinks to absorb carbon

The oceans no longer contain dissolved carbon

Photosynthesis has stopped globally

Natural sinks absorb carbon faster than humans release it

7. A farmer adds carbon-rich straw to the soil. Soon afterward, plants show nitrogen deficiency symptoms. What is the most likely explanation?

The straw releases toxins that block nitrogen uptake by plant roots

Rainfall triggered by the straw addition leaches nitrogen from the root zone

Decomposition of straw acidifies the soil, converting nitrates into gases

Soil microbes decomposing the carbon-rich straw immobilize available nitrogen in their biomass, temporarily reducing its availability to plants

8. Deforestation causes a “double carbon penalty” because it _______________________________

Releases carbon stored in trees and reduces the forest’s ability to absorb CO₂ in the future

Increases rainfall and removes carbon from the atmosphere

Reduces oxygen production but does not affect carbon dioxide levels

Stores more carbon in the soil and increases photosynthesis

9. Salt weathering is also known as _______________

Haloclasty

Thermoclasty

Hydroclasty

Cryoclasty

10. Which of the following rocks is most resistant to weathering?

Marble

Limestone

Shale

Quartzite

Question 1 of 10

Nutrient Cycling MCQs (Quiz 10)

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