Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ____________ is to ____________.
a. exergonic; spontaneous
b. exergonic; endergonic
c. free energy; entropy
d. work; energy

Verified step by step guidance

1. Understand the terms 'catabolism' and 'anabolism'. Catabolism refers to the breakdown of complex molecules into simpler ones, releasing energy. Anabolism is the process of building complex molecules from simpler ones, requiring energy input.
2. Recognize that catabolic reactions are typically exergonic, meaning they release energy. Anabolic reactions are endergonic, meaning they require energy input.
3. Consider the analogy in the sentence: 'Catabolism is to anabolism as ___ is to ___'. This suggests a comparison between two pairs of processes or concepts.
4. Identify the correct pair of terms that reflects the energy dynamics of catabolism and anabolism. Since catabolism is exergonic, releasing energy, and anabolism is endergonic, requiring energy, the correct pair would be 'exergonic; endergonic'.
5. Review the options provided: a. exergonic; spontaneous, b. exergonic; endergonic, c. free energy; entropy, d. work; energy. Option b correctly reflects the energy relationship between catabolism and anabolism.

Key Concepts

Catabolism

Catabolism refers to the metabolic pathways that break down molecules into smaller units, releasing energy in the process. It is typically associated with exergonic reactions, where energy is released as complex molecules are broken down into simpler ones, such as during cellular respiration.

Anabolism

Anabolism is the set of metabolic pathways that construct molecules from smaller units, requiring energy input. These processes are endergonic, meaning they consume energy to synthesize complex molecules like proteins and nucleic acids, essential for cell growth and repair.

Exergonic vs. Endergonic Reactions

Exergonic reactions are chemical processes that release energy, often associated with catabolic pathways. In contrast, endergonic reactions require an input of energy, characteristic of anabolic pathways. Understanding these terms helps in identifying how energy flows in biological systems, crucial for metabolism.