Carbon is an essential element for life how does its atomic structure allow it to form so many different molecules

This is because Carbon has four valence electrons (tetravalent) which gives it the ability to form up to four bonds differently with different elements/compounds. This gives rise to the creation of lots of compounds.

Carbon as an element also has atoms which fits into most substances thereby creating different possible compounds with others such as in carbohydrates, proteins, lipids etc. This is what makes Carbon an essential element for life.

meiosis is the first to occur after the nuclei of opposite of opposite mating types fuse

answer; both surfaces of the membrane are nonpermeable