Sambhav-2025

Approach / Explaination / Answer

Introduction

The nutrient cycle is the process through which essential elements, such as carbon and nitrogen, move between biotic (living) and abiotic (non-living) components of an ecosystem. This cycle ensures the continuous availability of nutrients necessary for life, maintaining ecological balance, and supporting biodiversity.

Body

The contribution of Carbon and Nitrogen Cycles :

• Carbon Cycle: The carbon cycle regulates the movement of carbon through the environment, facilitating energy flow and climate regulation.
  • Key Processes:
    • Photosynthesis: Plants absorb CO₂ from the atmosphere and convert it into glucose, which is used as an energy source.
    • Respiration: Both plants and animals release CO₂ back into the atmosphere through respiration.
    • Decomposition: Dead organisms decompose, releasing carbon into the soil and atmosphere.
    • Combustion: The burning of fossil fuels releases significant amounts of carbon into the atmosphere, contributing to global warming.
  • Contribution to Sustainability:
    • The carbon cycle is essential for climate regulation, as it controls the amount of carbon in the atmosphere, preventing extreme global temperature changes.
    • Oceans absorb around 30% of human-caused CO₂ emissions, playing a significant role in regulating the carbon balance.
    • The Amazon rainforest, often referred to as the "lungs of the Earth," absorbs approximately 2 billion metric tons of CO₂ annually, underscoring its critical role in carbon sequestration.
    • It also supports biomass production, which forms the base of food webs in ecosystems.
    • However, deforestation contributes nearly 10% of global CO₂ emissions, as trees store large amounts of carbon that are released when trees are cut down.
• The nitrogen cycle: It ensures the availability of nitrogen, an essential nutrient for plants and animals, particularly for building proteins and nucleic acids.
  • Key Processes:
    • Nitrogen Fixation: Microorganisms like Rhizobium bacteria convert atmospheric nitrogen (N₂) into ammonia (NH₃), making it usable by plants.
    • Nitrification: Ammonia is converted to nitrates (NO₃⁻) by nitrifying bacteria, which plants then absorb.
    • Assimilation: Plants absorb nitrates and convert them into organic compounds.
    • Ammonification & Denitrification: Decomposers break down organic matter, returning nitrogen to the soil, and bacteria convert nitrates back into nitrogen gas (N₂), completing the cycle.
  • Contribution to Sustainability:
    • The nitrogen cycle maintains soil fertility and supports plant growth, which in turn sustains the entire food web.
    • It helps in agricultural productivity, ensuring the availability of food for humans and animals.
    • The Green Revolution in the 1960s increased agricultural productivity through the use of nitrogen-based fertilizers, feeding billions of people worldwide.
    • However, the overuse of nitrogen-based fertilizers has led to soil acidification, water pollution, and eutrophication in aquatic ecosystems.

Conclusion

The carbon and nitrogen cycles are fundamental to maintaining ecosystem sustainability. They regulate key processes like climate control, food production, and soil fertility. To ensure long-term sustainability, it is crucial to adopt sustainable practices such as reducing emissions, protecting forests, and using fertilizers efficiently to maintain these essential cycles for future generations.