In the given figure,what does the part labeled '$a$' represent and what does it contain?

Which of the following are found in all plant cells and in euglenoids?

Which of the following plastids is coloured and contains carotenoids?

Consider the following five statements $(A$ to $E)$ with respect to the chloroplast shown below. Select the correct option stating which ones are True $(T)$ and which ones are False $(F)$.
$A$. It is impermeable and lacks porins.
$B$. It is selectively permeable,having carrier proteins for transport.
$C$. Stacked thylakoids one over other which is the site of production of assimilatory power.
$D$. Present between two grana and contains enzymes of dark reaction.
$E$. It contains enzymes for the synthesis of sugar and proteins.

$A$

$B$

$C$

$D$

$E$

What are $P$ and $Q$ in the given organelle?

Granum and stroma are parts of........