Proteins are needed by the organisms for growth, repair and maintenance of the body.

Proteins are essential macromolecules that play critical roles in the body, including:

1. Growth: Proteins are crucial for the development of tissues and promote growth in both children and adults. They contribute to muscle growth, organ development, and general cellular proliferation.

2. Repair: Proteins are involved in the process of repairing damaged tissues. This is especially important after injuries or surgical procedures, where the body requires more protein to rebuild tissues.

3. Maintenance: Proteins are vital for the continuous maintenance of body structures. They help in the renewal of cells and tissues and support various physiological functions.

Additionally, they play a role in enzyme and hormone production, immune function, and transportation of molecules within the body.