Discuss the role that  Oxygen (O2) plays in the global biosphere. (2 sentences)

What is the carina? carina is the last segment of the trachea; irritants stimulating this structure will cause a cough reflex O The carina is where the pharynx splits into the esophagus and trachea O The carina is an opening to the middle ear O The carina is where the conducting zone turns into the respiratory zone O The carina is a ridge of bone in the nasal cavity Question 16 Into which organ of the alimentary canal is bile secreted? O liver O duodenum O gall bladder O stomach O ileum

The reason oxygen diffuses into the tissues seen in internal respiration? a. the temperature differences b. the pressure gradient or difference in partial pressure of oxygen in arterial blood and that in a metabolically active tissue c. the larger the partial pressure of the veins d. .the ability of hemoglobin to bind avidly with oxygen