The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. ... Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.
DNA mutations that actually originate in the gametes is mainly responsible for genetic biodiversity existing in modern organisms. The term biodiversity actually refers to the variety as well as variability of life that is found on the planet earth. his variety can be seen between species, the ecosystem and within the species.<span />
The Griffith's experiment, the Avery-MacLeod-McCarty experiment, and the Hershey–Chase experiments were the set of experiments that established DNA as the key hereditary molecule. The Avery-MacLeod-McCarty experiment was an extension to the Griffith's experiment. The heat killed virulent S strain cells of the Griffith's experiment were lysed to form a supernatant containing a mix of RNA, DNA, proteins and lipids from the cell. The supernatent was equally divided into 3 parts after the removal of the lipids. The 3 parts were respectively treated with an RNAase to degrade the RNA, DNAase to degrade the DNA and proteinase to degrade the proteins. The treated supernatant was then added into the culture containing the non-virulent R cells. In case of the supernatant treated with the DNAse, no transformation of R cells into S cells occurred. The transformation of R cells to S cells occurred in the proteinase and the RNAse cases. This indicated that DNA was the hereditary molecule and not protein or RNA.

Isovelumetric relaxation and ventricular filling take place during Ventricular diastole.. Both occur during ventricular diastole when the ventricles are not actively contracting and ejecting blood. Ventricular diastole is the period during which the two ventricles are relaxing from contortions of contraction, then dilating and filling; atrial diastole is the period during which the two atria are relaxing, dilating, and filling.