I think it's
With some common bond, things might just get stickier!
Maybe refers to how sugar-phosphates form the backbone of DNA and RNA, helping it "stick" together, or maybe the "sugar" component, making it sticky.
When I'm with a group I'll be holding you tight;
This could mean like the phospholipids(that have phosphorus) in the cell membrane, which holds it together. Of course, people are made up of cells.
When alone, I'll protect you in the absence of light.
Phosphorus is used in the heads of matches, which would help you in the dark.
Not really sure… Just a guess