Biogeochemical Cycles
What are the four main spheres involved in biogeochemical cycles?
Lithosphere, Atmosphere, Hydrosphere, Biosphere
Which process removes CO₂ from the atmosphere?
Photosynthesis
What is the primary source of energy for most ecosystems?
The sun
What is the primary cause of ocean acidification?
Absorption of atmospheric CO₂ by seawater
What law of thermodynamics explains why energy transfer is inefficient?
Second law of thermodynamics (entropy increases)
Which cycle is primarily driven by rock weathering instead of atmospheric exchange?
Phosphours Cycle
What is the primary human activity disrupting the nitrogen cycle?
Use of synthetic fertilizers
How much energy is typically transferred between trophic levels?
10%
What is the consequence of excess nitrogen in water systems?
Hypoxia and dead zones due to algal blooms
Why are tertiary consumers more vulnerable to ecosystem disturbances?
They rely on a long food chain and receive the least energy
What process returns nitrogen gas to the atmosphere?
Denitrication
Why does excessive phosphorus in water cause environmental issues?
It leads to eutrophication and algal blooms
What type of organism feeds at multiple trophic levels?
Omnivores
Which type of pollution results from the bioaccumulation of toxic substances like mercury?
Biomagnification
Which element cycles between the geosphere, biosphere, and hydrosphere, but not the atmosphere?
Phosphorus
Why is sulfur essential to life?
It is a key component of amino acids and proteins
What role do decomposers play in the carbon and nitrogen cycle?
They break down organic matter, releasing CO₂ and nitrogen compounds into the environment
What is the term for the total amount of energy converted to organic matter by producers?
Gross Primary Productivity (GPP)
How does deforestation impact the carbon cycle?
It reduces CO₂ absorption and increases atmospheric carbon
What ecosystem has the highest net primary productivity (NPP)?
Tropical rainforests
What is the main difference between the phosphorus cycle and the nitrogen cycle?
The phosphorus cycle has no significant atmospheric component, while the nitrogen cycle does
In the nitrogen cycle, what type of bacteria convert ammonia into nitrate?
Nitrifying bacteria
Why are food chains usually limited to four or five trophic levels?
Energy is lost as heat at each transfer, leaving too little for higher levels
What is the key term for a species that has a disproportionately large impact on its ecosystem?
Keystone species
If a pesticide accumulates in an ecosystem, which trophic level is more affected?
Tertiary consumers