Explain why water is H2O, not HO2. Use the words valence electrons, atoms and molecules in your answer.

Here, Hydrogen is having the positive ion is placed at the first and oxygen is having negative ion is placed at the second position. Here, Hydrogen is having the positive ion is placed at the first and oxygen is having negative ion is placed at the second position. Therefore, it is written as H2O and not HO2.

Cell membrane : decides what enters and leaves, it also decides which proteins come in and out
passive transport : passive transport uses energy and i’m pretty sure it’s a transport that allows only some proteins to go through such as proteins