Final answer:
Reaction A (glucose to CO2 and H2O) and Reaction B (ADP and Pi to ATP) are generally irreversible in living systems due to gas release and energy changes, whereas Reaction C (CO2 and H2O to H2CO3) is reversible, especially important in pH balance in blood. Reactions deemed irreversible in biological systems could be reversed in closed systems under specific conditions.
Step-by-step explanation:
In chemical equilibria, a reaction is considered reversible if it can proceed in both the forward and reverse directions until a state of equilibrium is reached, where the rate of the forward reaction is equal to the rate of the reverse reaction. For a reaction to be irreversible, it often involves factors like gas evolution, precipitate formation, or significant energy changes. Let's analyze the reactions:
- A. C₆H₁₂O₆ → CO₂ + H₂O: This is an example of cellular respiration, which is typically irreversible under physiological conditions because it releases energy and CO₂ as a gas.
- B. ADP + Pi → ATP: The synthesis of ATP from ADP and Pi is essentially irreversible under normal cellular conditions due to energy investment, but in theory, it can be reversible in a different system like a controlled laboratory setting.
- C. H₂O + CO₂ → H₂CO₃: The formation of carbonic acid (H₂CO₃) from water and carbon dioxide is reversible and is an important reversible reaction in the blood, helping to maintain pH balance.
In cases where the reaction appears irreversible, such as reaction A, it could potentially be made reversible in a closed system where pressure can prevent the escape of a gaseous product, allowing the reverse reaction to occur.