Answer:
The plasma membrane is made up by a phospholipid bilayer with embedded proteins that separates the internal contents of the cell from its surrounding environment. Only relatively small, non- polar materials can easily move through the lipid bilayer of the plasma membrane.
Explanation:
Answer:
The cuticle is the hair's outer most layer which has shingle or scale like cells that overlap. ... The middle structure includes the cortex which provides strength, color and texture of the hair. The innermost structure is the medulla layer which is only present in large thick hairs.
Explanation:
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.
It is referred to as a selective semipermeable membrane because it only allows certain things through, due to the size and shape of whatever is trying to get through.
