Why do organisms need a constant supply of energy and what are 3 biological activities that require energy?

Organisms need a constant supply of energy to sustain life because all biological processes, such as growth, reproduction, movement, and maintaining homeostasis, require energy. Energy is necessary for these activities to occur, as it drives the various chemical reactions in cells.

To understand three biological activities that require energy, we can look at key processes in organisms:

1. Metabolism: Metabolism refers to all the chemical reactions that occur in cells to maintain life. It involves breaking down and building up molecules to provide the necessary components and energy for growth, repair, and other functions. These reactions require energy, and without it, metabolic processes would slow down or cease altogether.

2. Muscle Contraction: Muscles are responsible for movement in animals, including humans. Muscle contraction requires energy in the form of adenosine triphosphate (ATP) to facilitate the sliding of muscle fibers. ATP is the energy currency of cells, supplying the necessary energy for the interaction of proteins and the shortening of muscle fibers, allowing for movement.

3. Active Transport: Active transport is a process where substances move across cell membranes against a concentration gradient. This process requires energy to move molecules from an area of lower concentration to an area of higher concentration. Active transport is vital for maintaining proper ion balance, nutrient uptake, and waste removal in cells.

To find these three biological activities that require energy, you can consult biology textbooks, scientific articles, or reliable online sources that provide in-depth explanations of cellular processes and human physiology.