Final answer:
Oxygen is the most important gas for the survival of living organisms as it is used by cells in Respiration to provide energy. Plants produce this oxygen through photosynthesis, absorbing carbon dioxide and sunlight.
Step-by-step explanation:
The most important gas for the survival of living organisms is oxygen. Oxygen is important because it's used by cells in Respiration, a process where food molecules are broken down to provide energy for various biological functions. Notably, the process of cellular respiration, which takes place in the mitochondria of cells, needs oxygen to efficiently produce ATP (Adenosine Triphosphate) for energy. Without adequate oxygen, cells have to switch to less efficient processes like fermentation which can't sustain complex organisms for extended times.
Plants, through photosynthesis, absorb carbon dioxide and sunlight to produce oxygen and glucose, thereby playing a critical role in maintaining the oxygen level in the atmosphere. This symbiosis between plants and animals help sustain life on Earth.
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