How much of the oxygen in the atmosphere is absorbed by the ocean?

98%

Explanation:

98% of the oxygen found in the atmosphere is believed to come from phytoplankton, which are photosynthetic microscopic beings that live in the ocean's water column. By many scientists, these organisms are considered seaweed and are studied within botany.

Oxygen when absorbed by animals is used for cellular respiration, where glycoses are degraded releasing energy, water and carbon dioxide. Water from this process can be used on the organism itself for various purposes or released through excretion, perspiration and decomposition, while carbon dioxide is released during the respiration and decomposition process.

this is math not biology xd