Nitrogen is required for protein formation. What is responsible for the bulk of nitrogen fixation? A.
air

B.
animals

C.
bacteria

D.
lightning

To be or not to be that is da question

Vaccines are weakened forms of disease causing microorganisms, which are given to patients to prevent disease. after the vaccine is administered, the immune system responds by creating a(n) to recognize the a.) antibody, antibiotic b.) antigen, antibody c.)antibiotic, antibody d.)antibody, antigen

What type of appendages do sponges cnidarians roundworms annelids mollusks arthropods echinoderms and vertebrate have? jointed, not jointed, absent