What are the two unique characteristics shared by all birds

Explanation:

All birds usually have feathers and wings

a polymer is a chainlike molecule made up of small molecular units. these small molecular units are called monomers. monomers of polymer can be joined together either naturally or synthetically.  

lysosomes contain a variety of enzymes, enabling the cell to break down various biomolecules it engulfs, including peptides, nucleic acids, carbohydrates, and lipids (lysosomal lipase). the enzymes responsible for this hydrolysis require an acidic environment for optimal activity. hope i !