Continental drift lead at various times to the separation of land masses with respect to the evolutionary events this separation may have caused which of the following Allopatric speciation
Sympatric speciation
The big five mass extinctions
Goal oriented evolution
Heterochrony

the real answer is b. scintillation counter

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.