Bacteroid has a thick cell wall which is absent in a bacterial cell(its outer structure is made up of a cytoplasmic membrane).
Leukocytes are produced/stored in thymus, spleen, and bone marrow
Answer:
Adaptive immune responses are triggered by activation of antigen-specific T cells that produce antibodies against foreign antigens such as, for example, harmful viruses. These immune responses are useful to eliminate dangerous molecules from the body. In a normal immune reaction, the antibodies produced by T-cells target antigen molecules in order to be subsequently absorbed by phagocytic macrophage cells.
Autoimmune diseases are triggered by the response of the adaptive immune system against self-antigen molecules. Since the immune system can not eliminate antigens from the own body, this immune reaction generates an excessive inflammatory response, and it may lead to the damage of tissues and organs.
Answer: A scenario often presented to introductory physics classes is that of a "gravity tunnel" — a tube drilled from one side of the Earth to the other through the planet's center. The answer taught for nearly a half-century for how long a fall through such a hole would take was about 42 minutes and 12 seconds.
Explanation: However, solar and lunar gravity, which also perturb orbiting satellites, would eventually pull you into the tunnel wall anyway [source: Darling ]. Strike a chord: Fun fact: A straight line from any point to any other point through the planet would take the same amount of time to fall through like a tunnel through Earth's center.
