Biogeochemical Cycles Flashcards

Biosphere and Ecosystems

• The biosphere encompasses all regions of Earth where living organisms exist, including land, water, and the atmosphere.
• Biogeochemical cycles involve the movement of essential elements like water, carbon, oxygen, and nitrogen through both living (biotic) and nonliving (abiotic) components of an ecosystem.

Water Cycle Processes

• Precipitation refers to any form of water (rain, snow, sleet) that falls from the atmosphere to the Earth's surface, replenishing water sources.
• Transpiration is the process where plants release water vapor into the atmosphere from their leaves, contributing to the water cycle.
• Percolation is the movement of water through soil and rock layers, helping to filter and replenish groundwater supplies.
• Groundwater is water stored beneath the Earth's surface in soil pores and rock formations, integral for maintaining ecosystems and human consumption.

Carbon Cycle Processes

• Photosynthesis is a critical plant process that harnesses solar energy to transform carbon dioxide into carbohydrates, providing food for the base of the food chain.
• Carbon fixation is the conversion of inorganic carbon (like carbon dioxide) into organic molecules (like sugars), essential for building biomass in plants.
• Cellular respiration is used by living organisms to extract energy from carbohydrates, producing carbon dioxide as a byproduct and returning it to the atmosphere.
• Combustion refers to the burning of organic materials and fossil fuels, which releases carbon dioxide and contributes to atmospheric changes.

Nitrogen Cycle Processes

• Nitrogen-fixing bacteria convert atmospheric nitrogen gas into ammonia, making nitrogen available to plants in a usable form.
• Nitrogen fixation is the overall transformation of nitrogen gas into ammonia, essential for life as it forms the basis for amino acids and nucleic acids.
• Nitrification is a two-step process that converts ammonia into nitrites and then nitrates, which are also usable by plants.
• Decomposers, including bacteria and fungi, play a crucial role in breaking down dead organisms, cycling nutrients, and replenishing nitrogen in the soil.
• Denitrification is the conversion of nitrates back to nitrogen gas, returning it to the atmosphere and completing the nitrogen cycle.