Answer:
Number of bacteria required 
Explanation:
Given -
Size of each bacterium 
micrometers long
These bacteria are arranged end to end.
The size of chain to be formed is equal to 
centimetres
Let us say that in forming a chain of centimetres nearly X number of individual bacterium are required.
hence, number of bacterium required to form centimetres chain can be represented as
Number of bacteria required
A possible Hypothesis probably .
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.
Explanation:
<em>Immunological memory</em> is the property of the immune system to store information about a stimulus so it can mount an effective response if it encounters the same stimulus again being this second response quicker and stronger even after years since the first encounter.
This kind of response is dependent on many subpopulations within T and B lymphocytes and NK cells. When encountering an antigen, B cells recognize it by membrane antibody specifically binding to the antigen and then being activated to expand rapidly with their progeny clones differentiating into plasma and memory B cells, these last ones have a long life span to remain in the body, ready when another encounter with the same stimulus occurs, this is how the basis for effective immunizations happens.
I hope you find this information useful! Good luck!
