Why does a red blood cell unable to replace damaged protein?

The reason is because the cells are unable to replace and lack DNA and cell organelles such as nucleus, ribosomes and mitochondria which are crucial for protein synthesis, assembly and repair.  

From: Taskmasters, Ace

answer; ///(b) it is composed of four protein chains and four heme groups;

the elements of art are the visual tools that the artist uses to create a composition. these are line, shape, color, value, form, texture, and space.

the principles of art and design are balance, contrast, emphasis, movement, pattern, rhythm, and unity/variety.