Oxygen Cycle Explanation

We all know how important oxygen is for our sustenance, it is present in the air we breathe and the water we drink. With oxygen taking up 20.95% of dry air, it is the second most abundant gas on our planet.

Oxygen Cycle 2

Table of Contents

What is the Oxygen Cycle?

The oxygen cycle portrays how the flow of oxygen occurs through several parts of our vast ecosystem. Oxygen is found in several parts of the ecosystem, from the air we breathe (Atmosphere), the water bodies on the planet (Hydrosphere), inside all the biological beings (Biosphere) and inside the earth’s crust (Lithosphere).

reservoir of oxygen cycle


The biogeochemical cycle describes the movement of oxygen in the atmosphere (air), the biological matter of the ecosystem biosphere (the global sum of all ecosystems) and the lithosphere (earth’s crust).

Oxygen Cycle Steps:

  • Atmosphere:
    Only a small percentage of the world’s oxygen is present in the atmosphere, only about 0.35 %. This exchange of gaseous oxygen happens through Photolysis.

    • Photolysis: This is the process by which molecules like atmospheric water and nitrous oxide are broken down by the ultraviolet radiation coming from the sun and release free oxygen.
  • Biosphere:
    The exchange of oxygen between the living beings on the planet, between the animal kingdom and the plant kingdom. The exchange of oxygen in the biosphere is codependent on the Carbon cycle and hydrogen cycle as well. It mainly occurs through 2 processes.

    • Photosynthesis:
      The process by which plants make energy by taking in carbon dioxide from the atmosphere and give out oxygen
    • Respiration:
      The process by which animals and humans take in oxygen from the atmosphere and use it to break down carbohydrates and giving out carbon dioxide.
  • Lithosphere:
    The part of the planet contains most of the oxygen content through biomass, organic content and mineral deposits. These deposits are formed when free radical elements were exposed to free oxygen and over time they form silicates and oxides. This trapped oxygen is released back due to several weathering processes. Also, animals and plants draw nutrient materials from the lithosphere and free some trapped oxygen.
  • Hydrosphere:
    Oxygen dissolved in water is responsible for the sustenance of the aquatic ecosystem present beneath the surface. The hydrosphere is 33% oxygen by volume present mainly as a component of water molecules with dissolved molecules including carbonic acids and free oxygen.

Oxygen Cycle Steps

Frequently Asked Questions – FAQs


What is the oxygen cycle?

The cycle of oxygen describes the different forms in which oxygen is found and how it moves on Earth through various reservoirs. Three major oxygen reservoirs are present: the atmosphere, the biosphere, and the lithosphere. The hydrosphere, a subdivision of the biosphere, is often known by some people to be the fourth reservoir.


Why is the oxygen cycle important?

The primary cycles are respiration and photosynthesis in the biosphere. Respiration occurs when oxygen is consumed by animals and humans to be used in the metabolic process and carbon dioxide is exhaled. They are the major cycles of oxygen and each plays an important role in helping to sustain and retain life on Earth.


What is the oxygen cycle in simple terms?

The cycle of oxygen isthe distribution of oxygen through nature in different ways. Free in the air and dissolved in water, in excess of uncombined elements in the atmosphere, oxygen is second only to nitrogen. In order to respire, plants and animals use oxygen and return it as carbon dioxide (CO2) to the air and water.


What is the role of respiration in the oxygen cycle?

In the oxygen cycle, the purpose of breathing is to release carbon dioxide, which is then taken up by the plants to carry out photosynthesis, which releases oxygen that human beings use in breathing to create carbon dioxide for plants again, and this cycle continues.


What’s the difference between the carbon cycle and the oxygen cycle?

They work independently but are dependent on each other since the carbon cycle releases oxygen for the usage of the oxygen cycle, and the oxygen cycle emits carbon dioxide (CO2) that goes back to the carbon cycle in turn. The key vehicle in which the processes of oxygen and carbon are related plants.

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  1. its amazing THANKS A LOT