What type of gas is produced during respiration in living organisms?

During respiration in living organisms, carbon dioxide is produced as a byproduct of the metabolic processes that convert glucose and oxygen into energy. This process, known as cellular respiration, occurs in the cells of all living organisms, including plants, animals, and bacteria.

When organisms break down glucose in the presence of oxygen, they release energy, which is used for various cellular functions. In this process, oxygen is consumed, while carbon dioxide is generated. The carbon dioxide produced is then expelled from the body, for instance, through exhalation in animals or diffusion in plants, where it may eventually be utilized in photosynthesis.

In contrast, hydrogen and nitrogen do not play significant roles in the respiration process as outputs. Hydrogen is typically involved in the formation of water during cellular respiration, and nitrogen is primarily inert in this context, with no direct function in the respiration process of most organisms. Oxygen, while consumed during respiration, is not produced as a byproduct. Thus, carbon dioxide is the correct answer as it is the main gas generated during respiration.