A memory B cell is kinda of how it sounds it has a memory of what your body has fought before such as a virus and can stimulate a response quicker then the first time you encountered it.
If you lack memory B cells your body doesn't built up the same immune response when you come into contact with the virus again.
"Vaccination would prevent further disease" Incorrect, a vaccine lets you build up memory cells to combat the disease if you lack them you cannot build up a defense.
"Vaccination would not prevent further disease" Correct, a vaccine can be a dead version of a virus or parts of a virus that shows your body what to respond to quickly in the future. If you body cannot make memory b cells it wouldn't help to use a vaccine. Your body wouldn't keep a memory of it being bad.
"You would not produce antibodies" Even if your body does not remember a particular virus it does produce antibodies to combat it just not as quick or efficiantly as something it has come into contact with before and produced memory cells.
"You would over produce histamine" Incorrect, different process for that histamine.
In spherocytosis, there is a defect in the membrane proteins of the red blood cells, specifically ankyrin and spectrin. These membrane proteins contribute to the biconcave shape of red blood cells therefore the loss of these proteins will lead the red blood cells to lose its biconcave shape--leading to abnormally shaped red blood cells (spheres) hence the name. This can lead to premature destruction of red blood cells and jaundice due to hyperbilirubinemia. Spherocytes do not hold oxygen and carbon dioxide well as spherocytes have a decreased surface area.
In meiosis, the chromosome pairs do the crossing over where there is an exchange of genetic material between them and because of it the
chromatids held together by the centromere are no longer the same.