C. the crust and upper mantle
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Answer:
A source from which organisms generally take elements is called exchange pool (option B).
Explanation:
Options for this question are:
- <em>Food web.</em>
- <em>Exchange pool.</em>
- <em>Reservoir.</em>
- <em>Biotic community.</em>
The term exchange pool is related to the biogeochemical cycles that exist in nature, referring to the source from which elements present in the environment become part of living organisms.
<u>Exchange pools are the biotic components</u> -like animals and plants- of an ecosystem, which determine the passage of elements between living beings. An element can remain as a reservoir (abiotic) in the soil, and then be incorporated into the exchange pool.
Answer: Composition maybe?
Explanation:
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.
Learn more about memory B cell here : brainly.com/question/23423029
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