Final answer:
A young child's body is approximately 75 percent water, with the highest water content found in the brain and kidneys. The amount decreases to 50-60 percent in adults, with teeth having the least water content.
Step-by-step explanation:
The percentage of a young child's body that consists of water is approximately 75 percent of their body mass. As children grow into adulthood, the water composition decreases due to changes in the body, such as the size and proportion of organs, muscles, fat, and bone. The amount of water also varies in different organs and tissues of the body. For instance, the brain and kidneys are composed of about 80-85 percent water, while teeth have the lowest proportion at 8-10 percent.
It's also important to recognize that the water in the body is not only found within the cells (intracellular fluid), but also between the cells in tissues and organs (extracellular fluid). This water is crucial for cellular function and the overall well-being of the body. Water's ubiquitous role is highlighted by its presence in various bodily fluids such as blood plasma, cerebrospinal fluid (CSF), and lymph, as well as its necessity for biochemical reactions within cells.