How does oxygen availability affect cellular respiration?
Show The word respiration is commonly used to describe the process of breathing in oxygen and breathing out carbon dioxide. However, the term more formally refers to the chemical process organisms use to release the energy from food, which typically involves the consumption of oxygen and release of carbon dioxide. Because respiration releases energy it is chemically the reverse of photosynthesis, which uses energy from the Sun to make organic molecules. Photosynthesis and respiration are also connected ecologically because the vast majority of organisms use the oxygen produced by photosynthesis for respiration. Today, most organisms on land, freshwater and the oceans, including plants, use cellular respiration to extract the energy they need to function, grow, and reproduce. What is respiration?A summary of the overall process of cellular respiration Most of the flow of energy through the biosphere begins with photosynthesizing organisms. Some of that energy is then acquired by organisms, including animals, that eat photosynthesizing organisms (called herbivores), which in turn are consumed by other organisms including animals (carnivores), or by organisms that consume dead organisms (decomposers) to get their energy for growth, reproduction, and other functions. The process that these organisms use to extract the energy from their food is through the chemical process of aerobic (with oxygen) respiration, also called cellular respiration. Cellular respiration uses organic molecules from food (for example, the sugar glucose) and oxygen to produce energy that is stored in the molecule adenosine triphosphate (ATP), as well as heat. Cellular respiration also produces carbon dioxide and water. Cellular respiration evolved after early photosynthesizing bacteria began providing a steady source of oxygen, and became abundant once oxygen began to accumulate in the ocean and atmosphere. The earliest forms of life, and some bacteria today, only use anaerobic processes (respiration without oxygen) to produce energy. Anaerobic processes, including fermentation, also occur in organisms that use cellular respiration, such as in human muscles, but these anaerobic processes do not generate energy as efficiently as aerobic pathways. Bacteria that use anaerobic respiration also live in the stomachs of animals, such as cows and sheep, and help to break down the grass they eat. A byproduct of this anaerobic process is methane (CH4), a greenhouse gas. For this reason, the increase in livestock from the industrialization of agricultural activities over the last century has contributed to global warming. Respiration is affected by various environmental conditions, including:
Earth system model about respirationThe Earth system model below includes some of the processes and phenomena related to respiration. These processes operate at various rates and on different spatial and temporal scales. For example, carbon dioxide is transferred among plants and animals over relatively short time periods (hours-weeks), but industrial agricultural activities have altered livestock biomass over decades to centuries. Can you think of additional cause and effect relationships between respiration and other processes in the Earth system? Explore the Earth SystemClick the bolded terms (e.g. photosynthesis, productivity and biomass, and oxygen levels) on this page to learn more about these process and phenomena. Alternatively, explore the Understanding Global Change Infographic and find new topics that are of interest and/or locally relevant to you. Links to Learn More
How would lack of oxygen affect cellular respiration?Anaerobic metabolism and loss of adenosine triphosphate (ATP) occur when oxygenated blood is not delivered to cells, resulting in cellular membrane breakdown and anaerobic metabolism.
How does oxygen and carbon availability affect cellular respiration?While photosynthesis requires carbon dioxide and releases oxygen, cellular respiration requires oxygen and releases carbon dioxide. It is the released oxygen that is used by us and most other organisms for cellular respiration. We breathe in that oxygen, which is carried through our blood to all our cells.
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