<span>The correct answer is A, B and D. Biogeochemical cycles are central to the ecology of earth system. They make the essentail elements accessible and available for the organisms, and maintain their levels, so that the ecology is ot disrupted. The elements move through abiotic and biotic factors, in these cycles, and a state of equilibrium is maintained n the ecosystem. The carbon dioxide levels are responsible fr the temperature of the earth. If Carbon cycles would not have existed, then there would have been a disruption in maintaining the global temperature. Biogeochemical cycles basically continuously recycles the essential materials, for sustaining the life-forms.</span>
<span>Eukaryotic cells contain membrane-bound organelles, including a nucleus. Eukaryotes can be single-celled or multi-celled, such as you, me, plants, fungi, and insects. Bacteria are an example of prokaryotes. Prokaryotic cells do not contain a nucleus or any other membrane-bound organelle.</span>
The answer is Na + is entering the cell and the K + is leaving, during the depolarization phase of the action potential open Na + channels allow Na + ions to diffuse into the cell. This inward movement of positive charge makes the membrane potential more positive. The depolarization phase is a positive response sequence where open Na + channels cause depolarization which in re-occurrence causes more voltage gated Na+ channels to open.
The flight or fight hormone, adrenaline
