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

What are $P, Q,$ and $R$ in the given plant cell?

Match the following columns correctly.

Column-$I$	Column-$II$
$(a)$ Membrane-bound organelle	$(p)$ Ribosomes
$(b)$ Non-membrane-bound organelle	$(q)$ Mitochondria
$(c)$ Largest cell	$(r)$ Mycoplasma
$(d)$ Smallest cell	$(s)$ Ostrich egg

Which of the following is not true for a eukaryotic cell?

Consider the following statements and choose the correct statement.
$(i)$ The endomembrane system includes mitochondria,chloroplast and peroxisomes.
$(ii)$ Smooth endoplasmic reticulum is the major site for synthesis of lipid.
$(iii)$ Rough endoplasmic reticulum is actively involved in protein synthesis.
$(iv)$ Mitochondrial matrix possesses single circular $DNA$,a few $RNA$ and $80\; S$ ribosomes.
Which of the above statements are correct?

Which of the following are single membrane-bound organelles?