Enzyme may work if in it's optimum pH if the pH didn't match with the enzyme's pH, the enzyme will break down.
Enzyme will break down if the temperature so high it's called denaturation.
        
                    
             
        
        
        
The answer is Neogene
Explanation:
It cannot be Cenozoic because that is an era. Not a period. Paleogene, Neogene, and Quaternary (our current period) are all periods within the Cenozoic Era (our current era). On the geologic time scale, there are Eras, Periods, and Epochs (and a few more classifications). Humans first appeared in the Miocene epoch which is an epoch in the Neogene period (in the Cenozoic era). 
This is why the answer is Neogene.
Hope this helps...
 
        
                    
             
        
        
        
Diatoms have cell walls composed of silicon dioxide.
A. silicon dioxide.
        
                    
             
        
        
        
A person should know the effect of auxins as it helps in growth of the stems and the person should know how much he should cut otherwise will keep cutting it non uniformly affecting the plant growth and exposure to sunlight.