Answer:
2) phosphate group
Step-by-step explanation:
ATP or Adenosine Triphosphate is called as the energy currency of the cell. It is composed of adenine nitrogenous base, ribose sugar and three phosphate groups. The three phosphate groups in order of their closeness to ribose sugar are alpha, beta and gamma.
The two phosphoanhydride bonds between the three phosphate groups are high energy bonds. When ATP is hydrolyzed to release energy these bonds are broken. When the outermost phosphate group (gamma phosphate) is released high energy is released and ATP is converted into ADP. This reaction is usually used to provide energy to endergonic reactions.