Answer:
Positive feedback is used to build more contractions.
Explanation:
Positive feedback mechanism in humans is also observed during childbirth which is induced by the pressing of the ovarian wall by the baby.
The pressing sensation is passed to the brain via different nerves, and in response, the brain stimulates the pituitary to produce oxytocin.
Oxytocin is responsible for the contractions of the uterine muscles which cause the movement of the fetus towards the cervix, further increasing the stimulus.  
The positive feedback loop continues until the baby is born.
 
        
                    
             
        
        
        
Two main factors that must be taken in consideration are temperature and the pH level.
The temperature shouldn’t be too low as it slows down the rate of reaction, meaning that the enzyme will work slower, but also not too high as it will cause the enzyme to denature (stops working as it should). 
The pH level is pretty much the same, shouldn’t be not too low nor too high.
        
             
        
        
        
Answer:
The third choice.
Explanation:
It is near the Orion Arm and extremely far from the center. Although I don't know about the "tip"
 
        
             
        
        
        
A sedimentary rock can become an igneous rock by melting and solidification.
 
        
             
        
        
        
Answer:
I think they are both increase???
Explanation:
Because the more energy the hotter something gets. And if something is more frequent the more it happens, meaning a faster speed.