Nucleotide is a combination of a sugar, nitrogen base and phosphate groupment
A Dew forms on grass when water vapor forms when molecules cool and join together.
B Gases expand when heated and contract when cooled.
Smog is an abiotic factor affecting a biotic factor(s).
This is because smog isn't a living organism so it is abiotic while humans are multicellular organisms so therefore, they are biotic factors.
Smog has a negative effect on many biotic factors.
A vestigial organ, something that has yet to fall prey to evolution, but no longer serves a purpose, or the purpose it used to serve.