Sodium, potassium, chloride and calcium ions are important for establishing the resting potential of the cell. The sodium-potassium gradient is maintained by a pump which transports 2 potassium inside the cell and 3 sodium ions outside the cell.
The structure of plasma membrane makes it selectively permeable allowing it to regulate the passage of substances into and out of the cell. Small nonpolar molecules can easily across the phospholipid bilayer of plasma membrane because it is hydrophobic. Polar molecules and ion cannot easily across the hydrophobic portion of plasma membrane because it is hydrophilic. Polar molecules and ions usually across the plasma membrane with the help of transport proteins.
Answer:
oxygen , carbon , hydrogen , nitrogen , phosphorus , sulfur are some examples
A scientific law describes a behavior of something that occurs
