Final Answer:
Living cells maintain a balance by controlling materials that enter and leave through the selective permeability of their cell membrane. Without this ability, the cell cannot maintain metabolism and will die. The cell must regulate internal concentrations of water, ions, and other nutrients while eliminating waste products. Homeostasis in a cell is maintained by the cell membrane, which allows certain particles to pass through and keeps others out.
Step-by-step explanation:
The cell membrane is a complex structure that surrounds the cell and separates it from its external environment. It is composed of a phospholipid bilayer, which is selectively permeable due to the presence of embedded proteins and glycoproteins. This selectivity allows the cell to control what enters and leaves the cell, maintaining a balance or homeostasis within.
Water is essential for all living cells, as it serves as a solvent for various biochemical reactions and maintains the shape and structure of the cell. The concentration of water inside the cell is higher than that outside due to osmosis, which is the movement of water molecules across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration until equilibrium is reached. The cell membrane regulates this process by allowing water to enter or leave based on the concentration gradient.
Ions such as sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca2+) are also regulated by the cell membrane. These ions play various roles in the cell, including maintaining electrical potentials, facilitating enzymatic reactions, and regulating metabolic processes. The selective permeability of the cell membrane allows these ions to enter or leave based on their concentration gradient and specific transport proteins present in the membrane.
Other nutrients such as glucose, amino acids, and vitamins are also transported across the cell membrane through specific transport proteins or by passive diffusion. The selectivity of these transport proteins ensures that only specific molecules are allowed to enter or leave the cell, preventing unwanted substances from entering and maintaining metabolic processes within the cell.
Waste products such as carbon dioxide (CO2), lactic acid (LA), and urea (NH2CONH2) are eliminated from the cell through various processes such as respiration, fermentation, and excretion. The selective permeability of the cell membrane allows these waste products to exit the cell while preventing other molecules from entering.
In summary, living cells maintain a balance by controlling materials that enter and leave through selective permeability of their cell membrane. This process ensures that essential nutrients are transported into the cell while waste products are eliminated, maintaining metabolic processes within the cell while preventing unwanted substances from entering. This process is essential for maintaining homeostasis within the cell and preventing its death due to imbalances in internal concentrations of water, ions, and other nutrients.