In which phase does the synthesis of spindle fiber proteins occur?

During which phase does $DNA$ replication occur?

Given below are the two statements.
Statement $I$: Replication of $DNA$ occurs in the '$S$' phase of interphase in the cell cycle.
Statement $II$: Replication of $DNA$ takes place only once in the cell cycle.
In the light of above statements,choose the correct answer from the options given below:

During the $G_2$ phase,the number of $DNA$ molecules per chromosome is:

Interphase is called the resting phase because

If the nucleus represents a large size in proportion to the cytoplasm of a cell,it indicates that: