Carbon and Nitrogen Cycles

Carbon Cycle

  • All living organisms contain carbon, essential for life processes.

  • Carbon is cyclical, moving through different forms and reservoirs in the environment.

  • Once organisms die, carbon from their bodies is decomposed and returned to the ecosystem.

  • Decomposers like bacteria and fungi play a crucial role in breaking down dead matter.

  • Human activities such as burning fossil fuels release carbon into the atmosphere as carbon dioxide, contributing to climate change.

Key Concepts of the Nitrogen Cycle

  • Importance of Nitrogen:

    • Nitrogen is a vital component of molecules in living organisms, particularly in proteins and nucleic acids.

  • Forms of Nitrogen:

    • N: nitrogen gas in the atmosphere (78% of atmosphere).

    • NH₃: ammonia, a usable form for plants.

    • NO₃⁻ and NO₂⁻: nitrates and nitrites, forms that plants can absorb.

Processes in the Nitrogen Cycle:

  • Nitrogen Fixation:

    • Bacteria in soil and plant roots convert nitrogen gas into ammonia, nitrates, and nitrites.

    • Lightning can also convert nitrogen gas into these usable forms.

  • Denitrification:

    • Bacteria covert nitrates back into nitrogen gas, returning it to the atmosphere.

  • Uptake:

    • Plants absorb nitrogen from the ground through their roots, primarily in the form of nitrates.

  • Excretion:

    • Animals release nitrogen back into the environment through urine or feces (mostly as urea).

  • Feeding:

    • Animals obtain nitrogen by consuming plants or other animals.

  • Decomposition:

    • Breaks down dead organisms, releasing nitrogen back into the soil, making it available for reabsorption by plants.

    • This process is carried out by decomposers such as bacteria and fungi.

  • Human Impact:

    • Human-made fertilizers can enhance nitrogen levels in crops but can also lead to runoff and environmental concerns.

  • Overall Breakdown:

    • The nitrogen cycle comprises a series of processes that allows for the continuous use of nitrogen in different forms within ecosystems, emphasizing the connectedness of life and the environment.