What role do chemical reactions play in living organisms?

Chemical reactions are fundamental to the functioning of living organisms, as they enable various biochemical processes essential for growth, development, and the maintenance of homeostasis. These reactions underpin metabolic pathways, where substances are transformed through specific sequences of reactions, providing the necessary energy and building blocks for cellular activities.

For instance, through cellular respiration, organisms convert nutrients into energy, while anabolism involves the synthesis of complex molecules from simpler ones, which is crucial for growth and repair. Additionally, chemical reactions help regulate internal conditions, ensuring that an organism remains stable despite changes in the external environment. This balance is key to the health and survival of the organism, demonstrating the integral role that these reactions play in life.

The other options do not encompass the broad importance of chemical reactions in living systems; energy production is just one aspect, while the lifespan of cells and the assertion of irrelevance do not accurately reflect the crucial, dynamic processes that chemical reactions facilitate.