Which of the following statements correctly describes a difference between anabolic and catabolic reactions?

• A. Anabolic reactions build complex molecules from simpler ones, while catabolic reactions break down complex molecules into simpler ones.
• B. Anabolic reactions release energy, whereas catabolic reactions require energy input.
• C. Catabolic reactions are always non-enzymatic, while anabolic reactions are always enzymatic.
• D. Both anabolic and catabolic reactions only occur in animal cells.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the definitions of anabolic and catabolic reactions. Anabolic reactions are processes that build complex molecules from simpler ones, such as synthesizing proteins from amino acids. Catabolic reactions, on the other hand, break down complex molecules into simpler ones, such as breaking down glucose during cellular respiration.
2. Step 2: Analyze the energy dynamics of these reactions. Anabolic reactions typically require an input of energy (often in the form of ATP) to drive the synthesis of complex molecules. Catabolic reactions release energy as they break down molecules, which can be captured and used by the cell.
3. Step 3: Evaluate the enzymatic nature of these reactions. Both anabolic and catabolic reactions are catalyzed by enzymes to ensure they occur efficiently and under controlled conditions. The statement that catabolic reactions are always non-enzymatic and anabolic reactions are always enzymatic is incorrect.
4. Step 4: Consider the cellular context of these reactions. Both anabolic and catabolic reactions occur in all types of cells, including animal, plant, and microbial cells. The statement that they only occur in animal cells is incorrect.
5. Step 5: Based on the analysis, identify the correct statement. The correct description is: 'Anabolic reactions build complex molecules from simpler ones, while catabolic reactions break down complex molecules into simpler ones.' This aligns with the fundamental definitions of these processes.