How does the sodium atom bond to the chlorine atom ?

Explanation:

It is happening when a sodium atom loses an electron to a chlorine atom and because of that sodium atom is becoming a positive sodium ion and the sodium ions and chloride ions form an ionic lattice.

Sodium - Na

Chloride - Ch

Sodium and Chloride are both elements that cannot be found separately and free in nature but they are found as bonded together.

a scenario where a cell may be needed to perform a form of endocytosis is when transporting large molecules. a scenario where a cell may be needed to perform a form of exocytosis is when releasing the large molecule from the cell.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.