Approximately 4.5 billion years ago
Answer:
antigens
Explanation:
a vaccine may contain that
Answer:
24
Explanation:
24 mating pairs are illustrated in Model 1 .
1) pathogen enters body and releases chemoattractants
2) a phagocyte/macrophage is attracted by these chemicals
3) the phagocyte engulfs the pathogen using its pseudopodia
4) the membranes of both organisms fuse forming a phagosome
5) lysosomers in the phogocyte fuse with the phagosome, forming a phagolysosome
6) these enzymes digest the pahogen (hydrolyse the bonds)
7) the antigens of the pathogen are placed on the surface of the phagocyte making an APC (antigen presenting cell)
