In the given figure,what do the labeled parts '$a$' and '$b$' represent respectively?

How many of the following structures are membrane-bound?
Endoplasmic reticulum,Golgi apparatus,Ribosomes,Lysosomes,Mitochondria,Microbodies,Centrioles,Nucleolus,Vacuoles

Assertion $A$: Organelles in eukaryotic cells are membrane-bound.
Reason $R$: Organelles in prokaryotic cells are non-membrane-bound.
Which option is correct for Assertion $A$ and Reason $R$?

What is the full form of $EM$?

The best material for demonstrating streaming movement of protoplasm within living cells is

Identify the labels $A, B, C, D$ and $E$ in the given diagram. The following components are listed:
$(i)$ $SER$
$(ii)$ Ribosome
$(iii)$ Nucleus
$(iv)$ Nuclear pore
$(v)$ $RER$