The Oxygen Cycle: NCERT Geography Notes for UPSC Exam - Testbook

Oxygen Cycle: A Comprehensive Guide

Understanding Oxygen

What is Oxygen?

• Oxygen is considered a fundamental element on Earth.
• It is the most prevalent element in the human body.
• Oxygen makes up approximately 65% of the human body's mass, primarily in the form of water.
• Oxygen also constitutes about 30% of the Earth's mass and 20% of the atmosphere.

Oxygen Consumption Processes

1. Respiration
   • All living organisms, both plants and animals, use oxygen for their respiration.
   • They inhale oxygen and exhale carbon dioxide.
2. Decay
   • When plants and animals die, their decomposition process uses oxygen and releases carbon dioxide.
3. Oxidation
   • Oxidation, also known as rusting, is a process where iron gets converted into iron oxide.
   • Iron objects absorb oxygen during rusting.
4. Combustion
   • Combustion or burning is nearly impossible without oxygen.
   • Objects consume oxygen and release carbon dioxide when they burn.

Oxygen Production Processes

Photosynthesis

• Green plants use sunlight to convert carbon dioxide and water into nutrients.
• Photosynthesis in plants typically involves chlorophyll and results in the production of oxygen as a by-product.

Sunlight

• Some quantity of oxygen is produced when sunlight reacts with water vapor in the atmosphere.
• This process is involved in the oxidation of carbohydrates, resulting in the release of energy, carbon dioxide, and water.

What is the Oxygen Cycle?

• The oxygen cycle is the biogeochemical cycle that involves oxygen.
• The cycling of oxygen is a highly intricate process.
• Oxygen can be found in several combinations and chemical forms.
• It combines with nitrogen to form nitrates.
• Oxygen also combines with several other elements and minerals to form different oxides such as iron oxide, aluminium oxide, and others.
• Plants absorb carbon dioxide during photosynthesis.
• A significant amount of oxygen is produced from the decomposition of water molecules by sunlight during photosynthesis.
• Humans and animals consume oxygen and release carbon dioxide into the atmosphere through respiration.
• This carbon dioxide is again absorbed by plants for photosynthesis, and the cycle continues.

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