I would say excretion since that means the process of expelling waste matter.
Nitro fixation is the process in which bacteria returns nutrients to the soil
<span>sporophytes
</span><span>A sporophyte produces spores therefore those plants that have spores is called sporophyte. A sporophyte is a type of a diploid organism so, which means that meiosis must occur in order to be able to produce haploid cells containing half number of chromosomes. Meiosis in sporophyte occurs in an area called sporangia. The spores that are being created inside sporangia shall be release into the air. Mitosis is expected to take place on a single haploid spore in order to be a multicellular gametophyte.</span>
chemicals that are secreted from antigen-presenting cells then activate helper T cells describes the role of cell-to-cell communication during a response to an invasion of antigens.
Explanation: Antibodies are present on the surface of the cells, and binds specifically to antigens and can also engulf pathogen and process these cells presenting them to MHC class 2. This complex is activated by helper T cells to secrete antibodies and macrophages. This interaction of B-cell and MHC class 2 complex with helper T cell is cell-mediated immune response.