It depends on how old you are.
In active transport, materials move from an area of high concentration to an area of lower concentration (goes down the concentration gradient) and it requires or uses energy in the form of ATP (adenosine triphosphate)
The causes of the attractions and repulsion between molecules of water is that the oxygen and hydrogen atoms share electrons in bonds but its not equal. I hope this is the answer you are looking for! :)
Answer:
Valence
Explanation:
In an atom, the electrons at the outermost energy level is called as valence electrons. It is the valence electrons which participates and interacts with the other atoms and form bonds. The valence electrons of an atoms are important as they depict the chemical properties of an element.
Thus the valence electrons resides the outermost shell and surrounds the atomic nucleus.
