Answer:
The cells present in the stem are part of the xylem and phloem conductive tissues. They are characterized by being elongated and in tubular form because they transport the substances, the xylem transports water and inorganic mineral sales that the root absorbs from the soil. The phloem is responsible for transporting substances synthesized in photosynthesis.
Its tubular and elongated shape facilitates the transport of these substances
Answer:
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
Explanation:
Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete cytokines that regulate or assist the immune response.
Answer:
The second one is correct
Explanation:
A leukocyte is responsible for the immune system
