a) the t cells are mainly used in identifying antigens and releasing chemicals which attact macrophages (big immune cells which ‘eat’ antigens), to destroy the antigen. b cells are used in the production of antibodies. when they encounter a new antigen, plasma cells and memory cells are formed from the devision of a b cell. the memory cell remembers the antigen and which antibody to use, while the plasma cell makes the antibodies to fight a particular antigen or class of antigens
b) Antigens are substances that provoke an immune response (they’re the ultimate target for the immune system). Antibodies are simply proteins that are secreted as a result of the antigen provoked immune response. In short, antigens cause the disease and antibodies cure it.
c) Passive diffusion:
– involves carriers, channels, or direct diffusion through a membrane.
– always operates from regions of greater concentration to regions of lesser concentration.
– No external source of energy is required.
– directly uses ATP (for Primary Active Transport)
– possible to go against the concentration gradient.
– a source of energy is required to move the carrier and its materials.
d) Mitosis is simple cell division, ending up with two identical cells, each with both pairs of every gene.
Meiosis is cell division for gametes. This is a two step process, one cell divides to form four identical cells, each having half the DNA content of the mother cell.
e) The process of synapsis and crossing over occurs in meiosis I but not in meiosis II.
Meiosis I produces two haploid cells, but meiosis II produces four haploid cells.