As we are aware oxygen is absolutely essential for all living organisms to survive. The oxygen is the atmosphere is the source of ozone (O 3). It is also an atom in the molecule of water (H 2 O). 6 Step Two of Oxygen Cycle. It comprises about 21% of atmospheric air. In intervening steps the oxygen is incorporated in water, and in this form it can interlink with the water cycle or indirectly with carbon cycle. Oxide compounds, such as CO2 also contain oxygen. The Ozone layer protects organisms by preventing most of the ultraviolet and X-ray from reaching the earth’s surface. d) Oxygen cycle :- Oxygen in the atmosphere is used for respiration, combustion and formation of oxide of elements. Oxygen cycle, circulation of oxygen in various forms through nature. 7 Step Three in Oxygen Cycle. NCERT Notes: The Oxygen Cycle [Geography Notes For UPSC] NCERT notes on important topics for the UPSC civil services exam. Carbon dioxide is released by animals and used in plants in photosynthesis. In the simple example of the oxygen cycle shown below, you can see how oxygen is used and cycled by plants and animals. oxygen. These notes will also be useful for other competitive exams like banking PO, SSC, state civil services exams and so on. Animals take in oxygen through the process of respiration. Oxygen is an essential component of biological molecules like carbohydrates, fats, and proteins. All of these processes together make up the oxygen cycle. Plants and other producers use carbon dioxide in photosynthesis. 8 (No Transcript) 9 History of Oxygen. It is also present in dissolved form in water bodies and helps in the survival of aquatic life. Animals then break down sugars and food. Oxygen cycle. Plants and animals use oxygen to respire and return it to the air and water as carbon dioxide Oxygen Cycle. The oxygen cycle is the biogeochemical transitions of oxygen atoms between different oxidation states in ions, oxides, and molecules through redox reactions within and between the spheres/reservoirs of the planet Earth. The oxygen cycle is interconnected with the carbon cycle. Oxygen is an important component of life. Oxygen is sent back into the atmosphere during photosynthesis. Free in the air and dissolved in water, oxygen is second only to nitrogen in abundance among uncombined elements in the atmosphere. About 21% of our air is composed of oxygen. After carbon, oxygen is one of the most abundant elements on earth. Oxygen is balanced between the atmosphere and the ocean. The oxygen cycle is the cycle that helps move oxygen through the three main regions of the Earth, the Atmosphere, the Biosphere, and the Lithosphere. Published on Dec 9, 2015 Oxygen-cycle is referred to as the cycle that maintains the levels of oxygen in the atmosphere. The Oxygen Cycle Oxygen is constantly being used and created by different processes on planet Earth. In the air, it … We cannot survive without oxygen. Filed Under: Class 9, Natural resources Tagged With: ammonification, denitrification, nitrification, nitrogen, nitrogen cycle About Mrs Shilpi Nagpal Author of this website, Mrs Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed (I. P. University) and has many years of experience in teaching. In combined form, it is found both in Earth’s crust and in the air.