Mast cells play what key role in initiating an immune response?

Mast cell release histamine and heparins molecules that are significant in initiating/mediating the inflammatory response. This is why mast cells are highly granulated and are categorized as granulocytes. An example of such a response is when an allergen bind to the IgE of a mast cell inducing secondary communication mechanism inside the cell leading to release of the transmitters.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: