Answer:
In cotransport, a single ATP-powered pump that transports a specific solute drives the active transport of several other  solutes. Normally, sodium in waste is reabsorbed in the colon, maintaining constant levels in the body, but diarrhea  expels waste so rapidly that re-absorption is not possible, and sodium levels fall precipitously. To treat this life threatening condition, patients are given a solution to drink containing high concentrations of salt and glucose. The  solutes are taken up by sodium-glucose cotransporters on the surface of intestinal cells and passed through the cells into  the blood. This simple treatment has lowered infant mortality worldwide.
 
        
             
        
        
        
I choose the option C.
N2 + 3H2 = 2NH3
        
             
        
        
        
Answer:
A retrovirus is an RNA virus that is duplicated in a host cell using the reverse transcriptase enzyme to produce DNA from its RNA genome. The DNA is then incorporated into the host's genome by an integrase enzyme. The virus thereafter replicates as part of the host cell's DNA.
 
        
             
        
        
        
The answer is mutation
of genes.  The mutations were beneficial and gave the individuals of  the population
advantage and hence increased their survival. The classic features of birds
evolved one by one and gave birds advantage over their dinosaurs counterparts, especially the feature of small size. 
 
        
                    
             
        
        
        
Answer:
trees are bigger than most plants but they are still plants. they are producers. 
for example trees are producers and provide for termites that are primary consumers. spiders are secondary consumers and so on and the food chain goes on.