Dead tissue can be caused by what?
disease pollen counts advanced mathematics microorganisms migrating birds viruses Physical weathering harmful substances
A B C D E F G H
Leeches clean away the dead or infected tissue.
microorganisms can cause dead tissue.
Dead tissue can be caused by what? (A) disease (B) pollen counts (C) advanced mathematics (D) microorganisms (E) migrating birds (F) viruses (G) Physical weathering (H) harmful substances