Cytochrome oxidase is an enzyme involved in cellular respiration. It plays a crucial role in the electron transport chain, where it facilitates the transfer of electrons from a reduced substrate to molecular oxygen, producing water as a byproduct. This process consumes oxygen.

During germination, the seed embryo requires a substantial amount of energy for growth and development. This energy is derived from cellular respiration, which requires oxygen. Cytochrome oxidase's oxygen consumption supports the metabolic activities necessary for seed germination.

Therefore, cytochrome oxidase is the primary enzyme responsible for oxygen absorption during seed germination.