It is a catecholamine. It is also known as adrenaline. It will increase the heart rate and other flight or fight responses.
        
             
        
        
        
Answer:
Open circulatory systems are advantageous to some animals because they use less metabolic energy.
Explanation:
Open circulatory systems are also known as lagoon circulatory systems. In this systems the blood is not necessarily always inside the blood vessels; It leaves the heart and will directly irrigate the organs and then return by other means or mechanisms.
So that it can be understood more easily, it is necessary to think about this system acting in organisms much smaller and less complex than mammals or any other vertebrate of greater size. As this animals doesn't have a great size, they need to use less metabolic energy than more developed organisms, so this system allows them to save metabolic energy to be used in other living functions.
 
        
             
        
        
        
Answer:
see below :)
Explanation:
Infectious are more easily spread nowadays becuse of an increased population. The more the population increases, the bigger the advantage an infectious disease has. As of right now, because everyone is wearing masks, their immune systems are being weakened. Another reason for this is because of the increase in chemicals in our foods, which are now being transferred to our bodies. All of the medications people are taking also have an affect on the spread of disease; it gives diseases a chance to mutate.
 
        
                    
             
        
        
        
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Answer:
An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons and neutrons, and the outer region of the atom, which holds its electrons in orbit around the nucleus.
Explanation: