Where does the energy required for anabolic reactions primarily come from?

• A. GTP (guanosine triphosphate)
• B. ATP (adenosine triphosphate)
• C. FADH2 (flavin adenine dinucleotide)
• D. NADH (nicotinamide adenine dinucleotide)

Answer: (B)

Verified step by step guidance

1. Understand the concept of anabolic reactions: Anabolic reactions are processes that build larger molecules from smaller ones, requiring energy input.
2. Identify the primary energy currency of the cell: ATP (adenosine triphosphate) is the main molecule that provides energy for cellular processes, including anabolic reactions.
3. Compare ATP with other energy carriers: While GTP, FADH2, and NADH also play roles in cellular energy transfer, ATP is the most widely used energy source for anabolic reactions.
4. Recognize the role of ATP in energy transfer: ATP releases energy when its terminal phosphate group is removed, forming ADP (adenosine diphosphate) and an inorganic phosphate, which is used to drive anabolic reactions.
5. Conclude that ATP is the primary energy source for anabolic reactions, as it is directly involved in providing the necessary energy to synthesize complex molecules.