Water Cycle
This process moves water from Earth’s surface into the atmosphere using heat energy.
Evaporation
In what form does most nitrogen exist in the atmosphere that plants cannot use directly?
Nitrogen gas (N₂)
What process allows plants to remove carbon dioxide from the atmosphere?
Photosynthesis
What term describes a rapid increase in algae caused by excess nutrients?
Algal bloom
Which Earth system includes rivers, lakes, and groundwater?
Hydrosphere
What is the process called when water vapor cools and forms clouds?
Condensation
Which organisms perform nitrogen fixation and denitrification?
Bacteria
What process returns carbon dioxide to the atmosphere from living organisms?
Cellular respiration
What term describes low oxygen conditions in aquatic ecosystems?
Hypoxia
Which Earth system contains soil and rocks?
Geosphere
Which process allows water to move from soil into the underground ?
Infiltration
What process converts nitrates into nitrogen gas, removing nitrogen from ecosystems?
Denitrification
What process adds carbon dioxide to the atmosphere when fossil fuels are burned?
Combustion
Which biogeochemical cycle is most directly affected by fertilizer runoff?
Nitrogen cycle
Which Earth system includes plants, animals, and bacteria?
Biosphere
Which human activity most directly reduces groundwater recharge?
Urbanization / paving surfaces
What environmental problem is most commonly caused by excess fertilizer runoff?
Eutrophication
What term describes oceans acting as long-term storage for carbon?
Carbon sink
Why does eutrophication often lead to fish death?
Decomposers use oxygen while breaking down algae.
How can a human-caused change in one Earth system lead to changes in multiple systems?
A human-caused change in one Earth system can affect others because the systems are interconnected. For example, fertilizer use changes the geosphere, runoff carries nutrients into the hydrosphere, algal blooms affect organisms in the biosphere, and oxygen levels or gases can change in the atmosphere.
Explain how the water cycle connects the biosphere and atmosphere.
Plants release water vapor through transpiration, moving water from the biosphere to the atmosphere
Explain why fertilizer runoff and denitrification have opposite effects on nitrogen levels.
Runoff adds excess nitrogen; denitrification removes nitrogen by returning it to the atmosphere
How have humans disrupted the carbon cycle, and what is one solution to reduce the impact?
Burning fossil fuels increases CO₂; solutions include renewable energy or reforestation
Which human activity affects the water, nitrogen, and carbon cycles, and why?
Agriculture or fossil fuel combustion; they alter nutrients, carbon emissions, and water runoff
Explain how a single human action can cause cascading changes across all four Earth systems.
A single human action, such as fertilizer use, can cause cascading changes across all four Earth systems. Fertilizer is applied to soil in the geosphere, runoff carries nitrates into rivers in the hydrosphere, algal blooms harm fish and other organisms in the biosphere, and oxygen levels or atmospheric gases can be altered in the atmosphere. Because the systems are connected, one change can spread through the entire Earth system.