Question

energy can be changed from one form to another
energy can be stored in chemical bonds & then released later
what do cells use energy for?
1.
2.
3.

Explanation:

Cells use energy for various essential life - sustaining processes. One key use is for active transport. This is when cells move substances against their concentration gradient (from an area of low concentration to an area of high concentration). For example, nerve cells maintain a proper balance of ions (such as sodium and potassium ions) across their membranes through active transport, which requires energy.

Another use is for synthesis of macromolecules. Cells need to build proteins, nucleic acids (like DNA and RNA), carbohydrates, and lipids. The formation of these large molecules involves chemical reactions that require energy input. For instance, the synthesis of a protein from amino acids involves a series of reactions that are energy - consuming.

Also, cells use energy for cell division. The process of mitosis (in somatic cells) or meiosis (in reproductive cells) is complex. It involves tasks like duplicating the DNA, separating the chromosomes, and physically dividing the cell into two daughter cells. All these steps need energy to occur accurately.

Answer:

1. Active transport (e.g., maintaining ion gradients in nerve cells).
2. Synthesis of macromolecules (e.g., proteins, nucleic acids).
3. Cell division (e.g., mitosis or meiosis).