The immune system helps fight off infections and foreign invaders
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.
All eukaryote cells lack a nucleus
It's about the size of our sun and called a Main sequence star
Protein channels + no energy spent + following concentration gradient = passive transport via facilitated diffusion :)
