Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What is the main role of ATP in cellular processes?

1. To store genetic information

2. To act as a structural component of cells

3. To supply energy for biochemical reactions

4. To transport nutrients across the cell membrane

The correct answer is: To supply energy for biochemical reactions

The primary role of ATP (adenosine triphosphate) in cellular processes is to supply energy for biochemical reactions. ATP serves as the energy currency of the cell, providing readily accessible energy that fuels various cellular activities, including metabolic reactions, muscle contractions, and active transport. When ATP is hydrolyzed, it releases energy that can be harnessed by enzymes and other proteins to perform work needed for the maintenance and growth of the cell. In detail, when a phosphate group is removed from ATP, it converts to ADP (adenosine diphosphate) and releases energy that is essential for driving endergonic (energy-requiring) reactions. This process underlies many vital functions, such as the synthesis of molecules, cell division, and signal transduction. The continuous regeneration of ATP from ADP and inorganic phosphate through cellular respiration further highlights its central role in energy transfer within cells. The other options reflect different cellular functions but do not pertain to the fundamental energy-supplying role of ATP. For instance, while genetic information is stored in DNA, structural components of cells include proteins and lipids, and nutrient transport typically involves different mechanisms and molecules such as transport proteins.