Answer:
Multicellular organisms must keep their cells awash in an "internal pond" because:
* To transport nutrients and oxygen to the cells and remove waste products. The internal pond, or extracellular fluid, is a watery solution that surrounds all of the cells in the body. It contains dissolved nutrients, oxygen, and other essential molecules that are needed by the cells. It also contains waste products that need to be removed from the cells. The extracellular fluid is constantly being pumped around the body by the heart and circulated through the blood vessels. This helps to ensure that all of the cells in the body have a constant supply of nutrients and oxygen, and that waste products are quickly removed.
* To maintain a constant internal environment. The internal pond helps to maintain a constant internal environment for the cells. This is important because many of the chemical reactions that take place in the cells are very sensitive to changes in temperature, pH, and other factors. The extracellular fluid helps to buffer these changes and keep the internal environment stable.
* To protect the cells from injury. The extracellular fluid helps to protect the cells from injury by cushioning them from bumps and knocks. It also helps to prevent the cells from drying out.
* To provide a medium for cell growth and division. The extracellular fluid provides a medium for cell growth and division. It contains nutrients that are needed by the cells for growth, and it also helps to remove waste products that are produced by the cells.
The internal pond is an essential part of multicellular organisms. It helps to keep the cells healthy and functioning properly.