Final answer:
Building more complex and ordered molecules requires energy, while breaking down complex molecules releases energy.
Step-by-step explanation:
Building Complex Molecules and Releasing Energy
In biological systems, the process of building more complex and ordered molecules requires energy and is known as anabolic reactions. Anabolic reactions use simpler compounds to create complex molecules and typically involve endergonic reactions that require an input of energy. On the other hand, breaking down complex molecules releases energy and is called catabolic reactions. Catabolic reactions involve exergonic reactions that release energy.