The portion of the tooth that is used for mastication and is visible in the oral cavity is the
a. root.
b. cervix.
c. gingiva.
d. crown.

in situ hybridization has been widely used for research applications, including clinical cytogenetics, gene mapping, tumor biology and studies of chromosome evolution.

it's c.us forest service

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

1) a

2)c

3)a

4)c

5)b

hope this , if so, your appreciation would be signified through giving   me brainliest, and a you : ) have any further questions? feel   free to ask me in the questions box.