Final answer:
Chemical reactions in living systems occur in an aqueous environment, and they depend on a precise range of temperatures and pH to function correctly.
Step-by-step explanation:
Chemical reactions in living systems occur in an aqueous environment, within a narrow range of temperatures. This environment not only supports the construction of biomolecules but also facilitates the interactions between them. Temperature moderation by water ensures that chemical reactions progress optimally. Most organisms' bodies can only tolerate a limited range of about 10 °C in body temperature and two-tenths of a unit in blood pH levels before their biochemistry is affected. Chemical reactions, especially those catalyzed by enzymes, depend on a balanced environment to function correctly, since both high and low temperatures and pH levels can lead to the denaturation of enzymes, inhibiting biochemical reactions.