Answer:
E. are found in nitrogen-fixing cyanobacteria AND are used to protect nitrogenase.
Explanation:
Heterocysts are specialized cellular compartments found in nitrogen fixing cyanobacteria. They provide the ideal anaerobic environment for nitrogen fixation since nitrogenase enzyme cant work in presence of oxygen. Hence, in a cyanobacteria both the oxygen requiring photosynthesis process and the  oxygen sensitive nitrogen fixation process takes place simultaneously. 
Heterocysts have an additional cell wall made of glycolipid that provides a hydrophobic barrier to oxygen. They are involved in production of nitrogenase and other proteins that are required for nitrogen fixation. They also degrade photosystem II which is responsible for producing oxygen and produce proteins which remove any remaining oxygen. 
 
        
             
        
        
        
I think dna replication are inportant because of the cells in the dna
        
             
        
        
        
I think the answer would be A 
        
             
        
        
        
Answer: D) alpha: catabolism 
Explanation:
Glycogen is the storage form of carbohydrates in animals. The major sites of storage are liver and muscle.
Glucagon is a polypeptide hormone, it is secreted by the alpha cells of the pancreas. Low blood glucose causes glucagon secretion. When blood glucose level falls, liver glycogen is broken and help to maintain blood glucose level. 
Glucagon stimulates the enzyme glycogen phospholylase which breaks down glycogen into glucose units.