Vitamin $B_{12}$ is also known as:

The given structure represents a low molecular weight organic compound found in living tissues. Identify the category and the missing component $X$ in the structure.
Category $-$ Component

In which organ of the human body does glycogenolysis occur?

In which of the following is phosphorus a major component?

Which of the following are aromatic amino acids?

Select the correct match for $X$ and $Y$.

Column $X$	Column $Y$
$(1)$ Starch	$(P)$ Found in animal skeletal tissues
$(2)$ Glycogen	$(Q)$ Stored food form in plants
$(3)$ Chitin	$(R)$ Provides strength in sclerenchyma
$(4)$ Lignin	$(S)$ Stored food form in animals