Which statement about ATP is true?

Which statement about ATP is true?

• A. Adenosine triphosphate is an energy-rich compound that serves as the immediate source of energy for most body reactions.
• B. ATP is produced only in the mitochondria and never used for muscle contraction.
• C. ATP cannot be broken down to ADP.
• D. ATP is formed by combining adenosine with four phosphate groups.

Answer: (A)

ATP is the immediate energy currency of the cell. It stores energy in the high-energy bonds between its phosphate groups, and when the terminal phosphate is released through hydrolysis, energy is liberated to power other cellular processes. This quick release is what drives most body reactions, including muscle contraction, where energy from ATP hydrolysis powers the myosin motor proteins to slide along actin filaments. The idea captured here is that ATP provides rapid, readily available energy for work across the cell. The other statements aren’t accurate: ATP isn’t produced only in mitochondria—glycolysis in the cytoplasm also generates ATP, and mitochondria produce much of it but aren’t the sole site. ATP is used for muscle contraction, not kept separate from it. ATP can indeed be broken down to ADP (and to AMP under some conditions). And ATP consists of three phosphate groups, not four.

ATP is the immediate energy currency of the cell. It stores energy in the high-energy bonds between its phosphate groups, and when the terminal phosphate is released through hydrolysis, energy is liberated to power other cellular processes. This quick release is what drives most body reactions, including muscle contraction, where energy from ATP hydrolysis powers the myosin motor proteins to slide along actin filaments. The idea captured here is that ATP provides rapid, readily available energy for work across the cell.

The other statements aren’t accurate: ATP isn’t produced only in mitochondria—glycolysis in the cytoplasm also generates ATP, and mitochondria produce much of it but aren’t the sole site. ATP is used for muscle contraction, not kept separate from it. ATP can indeed be broken down to ADP (and to AMP under some conditions). And ATP consists of three phosphate groups, not four.