<span>Norepinephrine uses the Second
Messenger System, which means, cells signal to each other what molecules have
been released that will trigger a physiological reaction. </span>
<span>
This phenomenon is activated after the ligand (ion or molecule) is bonded to its receptor
(protein molecule), creating a variation that causes a chain-reaction, that will
finally activate the Second Messenger. The latter will activate intercellular
molecules that will be able to control the cell’s activity. </span>
We are dependent on photosynthesis because photosynthesis is an essential process in our natural environment that helps to sustain plant life, produce oxygen, reduce Co2, and promotes human and animal well-being.
To primary consumers, as they directly eat producers and are next on the level of animals in an ecosystem.
<span>What is the approximate age of our solar system?
</span>b. 4.6 billion years
i believe that it is chromosomes
