Answer:
Amino acids with non-polar side chains. 
Explanation:
The class of proteins that is unable to form hydrogen bonds with water are the amino acids with non- polar side chains. This class includes the amino acids 
Alanine
Valine
Leucine
Isoleucine
 Proline 
Phenylalanine
Cysteine 
 Methionine
 Tryptophan 
These are the nine proteins which are considered to be strongly hydrophobic. All these amino acids are hydrophobic in nature due to their side chains. Glycine is not added to this list as it does not have a side chain. 
 
        
             
        
        
        
Answer:
it cannot be easily degraded in our environment.Like humans, animals and plants are exposed to PBTs in the environment through air, water and food. ... Persistent bioaccumulative toxic substances (PBTs) are chemicals that do not degrade easily in the environment.
 
        
             
        
        
        
Answer:
Explanation:
Descripción Las variables dependientes e independientes son variables en modelos matemáticos, modelos estadísticos y ciencias experimentales. Las variables independientes son entradas controladas. Las variables dependientes representan la salida o el resultado resultante de alterar estas entradas.
 
        
             
        
        
        
The organelle that acts like the brain or the control center in the cell in the nucleus.
Hope this helps!!! :D