8
Curiosity
Earth as a System: Energy, Matter and Life
250+ practice questions available
Sample Practice Questions
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1
easy
Which of the following is an example of a biogeochemical cycle?
AWater cycle
BRevolution of Earth around the Sun
CTectonic plate movement
DMountain formation
2
medium
Nitrobacter bacteria are important because they:
AFix atmospheric N₂ into ammonia
BConvert nitrites to nitrates (second step of nitrification)
CConvert nitrates back to N₂
DConvert organic nitrogen to ammonia
3
medium
Which of the following processes releases oxygen into the atmosphere?
APhotolysis of water during photosynthesis
BCombustion of organic matter
CRespiration in animals
DDecomposition of organic matter
4
hard
In the nitrogen cycle, why is denitrification ecologically important even though it reduces soil fertility?
ADenitrification produces nitrous oxide (N₂O) which is needed for plant growth
BDenitrification is not actually ecologically important; it is only a concern for farmers
CWithout denitrification, nitrogen would permanently accumulate in ecosystems; denitrification completes the cycle and maintains the nitrogen balance between atmosphere and biosphere
DDenitrification creates ammonia needed for acid rain
5
medium
Which of the following best explains how biodiversity loss can disrupt biogeochemical cycles?
ABiodiversity loss always increases nutrient cycling efficiency
BOnly the loss of top predators affects biogeochemical cycles
CLoss of key species (decomposers, nitrogen-fixers, mycorrhizal fungi) reduces cycling efficiency and resilience of nutrient cycles
DBiodiversity loss only affects the water cycle
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