The answer is : randomization was not used in sample selection. The major difference between experimental and quasi-experimental designs is lack of randomization in sampling selection.
If you are talking about frequency in terms of waves, it is in seconds^-1
The higher biodiversity in an ecosystem means that there is a greater variety of genes and species in that ecosystem. A great variety of genes and species means that the ecosystem is better able to carry out natural processes in the face of external stress. Thus, the ecosystem is more sustainable.
Nucleic acids contain the genetic code.
