The student who caught the cold caused by this specific Rhinovirus was exposed to the exact same Rhinovirus 18 months later. Memory B cells of the immune system will protect her from getting the same cold again.
In immunology, a memory B cell (MBC) is a type of B lymphocyte that forms part of the adaptive immune system. These cells develop within germinal centres of the secondary lymphoid organs.
Memory B cells circulate in the blood stream in a quiescent state, sometimes for decades. Their function is to memorize the characteristics of the antigen that activated their parent B cell during initial infection such that if the memory B cell later encounters the same antigen, it triggers an accelerated and robust secondary immune response.
Memory B cells have B cell receptors (BCRs) on their cell membrane, identical to the one on their parent cell, that allow them to recognize antigen and mount a specific antibody response.
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For the first question, i think the correct answer is A. Normal cells undergo apoptosis while cancer cells don't. For the second question, The answer is option B.<span> </span><span>Cell division has two checkpoints namely, G1
checkpoint and spindle assembly checkpoint. The checkpoint which determines if
division has properly occurred is the G1 checkpoint. At this point, is a damage
in the DNA is detected or the has not reach the optimum size, the cell is
stopped in G1 and is not allowed to proceed to further process.</span>
Mantle convection causes tectonic plates to move around the Earth's surface.
Explanation:
A- meiosis
B- zygote
Cell B is described as diploid cells because two haploid cells n(40) fuses together to form diploid cell 2n(80)