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 decomposer, as it is breaking down organic matter

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

A recycler, as it is returning carbon to the soil

A nutrient sink, as it is absorbing more carbon

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

Nitrite ions, because nitrogen is partially oxidized in anaerobic soils

Ammonium ions, because oxygen is absent and nitrification cannot occur

Nitrate ions, because nitrifying bacteria are active without oxygen

Nitrogen gas, because ammonification directly releases gaseous nitrogen

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

Human emissions exceed the capacity of natural sinks to absorb carbon

Natural sinks absorb carbon faster than humans release it

Photosynthesis has stopped globally

The oceans no longer contain dissolved carbon

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

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

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

Decomposition of straw acidifies the soil, converting nitrates into gases

The straw releases toxins that block nitrogen uptake by plant roots

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

The number of trophic levels through which nutrients pass

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

The speed at which plants absorb minerals from the soil

The cost of adding fertilizers to agricultural land

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

Marble

Quartzite

Limestone

Shale

7. Which rock characteristic most strongly affects weathering susceptibility?

Rock location

Rock color

Mineral composition

Rock age alone

8. Salt weathering is also known as _______________

Thermoclasty

Haloclasty

Cryoclasty

Hydroclasty

9. The rate of weathering generally increases with ____________________

Decreasing moisture

Increasing temperature and moisture

Decreasing temperature

Increasing rock size

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

Reduces oxygen production but does not affect carbon dioxide levels

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

Stores more carbon in the soil and increases photosynthesis

Increases rainfall and removes carbon from the atmosphere

Question 1 of 10

Nutrient Cycling MCQs (Quiz 10)

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