Either, carbon, hydrogen, nitrogen, oxygen, phosphorus, or sulfur. I would go with carbon because of the photosynthesis and cellular respiration<span />
        
                    
             
        
        
        
Melting of ice and island decreasing in level
        
                    
             
        
        
        
The conduction of nerve impulses relies upon the movement of positively-charged ions across the nerve cell membrane. The entry of sodium into the cell produces a wave of positive charge that travels down the length of an axon. Then chemicals called neurotransmitters are secreted out of the end of the axon onto the next nerve in the series (the postsynpatic nerve). This narrow space in between neurons is called the synapse. These neurotransmiiters released by the presynaptic nerve bind to receptors on the postsynaptic nerve. The binding of these receptors opens up channels in this second nerve's membrane that allow sodium ions to enter the nerve cell and initiate another wave of positive charge, and so on... The nerve signal can only move as fast as these ions and neurotransmitters can diffuse to generate this process. 
<span>As a professional athlete repeats a given activity many times over, the nerve cells "upregulate" their receptors, meaning that they produce additional receptors to put in the membrane. This is just a natural reaction to the nerve being repeatedly stimulated in the same way over and over. When neurotransmitter is secreted from the presynaptic neuron, there are more receptors on the postsynaptic neuron for it to bind, more channels open up, more ions enter in a shorter time and build up positive charge to create the impulse faster, and so the overall effect is faster. </span>
<span>Additionally, there are sheaths of fatty tissue (called myelin) that insulate the charge in the neuron and allow it to be conducted faster. As people age, these sheaths can start to degrade, making the nerve cell more "leaky" and causing the impulse to be conducted more slowly. </span>
        
                    
             
        
        
        
The overall magnification of a microscope is calculated by multiplying the objective lens's magnification by the optical lens' magnification.
However, you must first ascertain the optical lens's magnification power before computing the total magnification.  The ocular lens typically magnifies 10 times.
Find out how much the objective lens can magnify. On the side of the lens is printed the magnification. The value may formerly be 4X, 10X, 40X, or 100X. 
Multiplying the ocular lens' magnification power with the objective lens' power yields the compound light microscope's overall magnification. For instance, a 400X total magnification would be achieved with a 10X ocular and a 40X objective. The compound light microscope has a maximum total magnification of 1000X.
Learn more about microscopes here:
brainly.com/question/13520094
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