Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
Answer:
I believe it is the "Nucleus."
Explanation:
Hope my answer has helped you!
The cell membrane allows substances to enter and leave the cell and gives the cell structure.
Answer:
a biological community of interacting organisms and their physical environment.
Explanation:
