Complex sentence: The isolated reaction of anabolism is unfavorable in a cell due to a positive Gibbs Free Energy (+ Δ "G"); thus, an input of chemical energy through a coupling with an exergonic reaction is necessary.
Split into simpler sentences: The isolated reaction of anabolism is unfavorable in a cell due to a positive Gibbs Free Energy (+ Δ "G"). Thus, an input of chemical energy through a coupling with an exergonic reaction is necessary.