The magnification of a light compound microscope having a $15x$ eyepiece lens and a $45x$ objective lens will be .........

Match List $I$ and List $II$ and select the correct answer using the code given below the list:

List $I$	List $II$
$a$. Lysosome	$1$. Bacteria without cell walls
$b$. Mycoplasma	$2$. $A$ virus that infects bacterial cells
$c$. Thylakoid	$3$. Flattened sacs in a chloroplast
$d$. Bacteriophage	$4$. $A$ vesicle in which hydrolytic enzymes are stored

Code:

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

Match Column-$I$ with Column-$II$ and select the correct option.

Column-$I$	Column-$II$
$(a)$ Thylakoids	$(i)$ Disc-shaped sacs in Golgi apparatus
$(b)$ Cristae	$(ii)$ Condensed structure of $DNA$
$(c)$ Cisternae	$(iii)$ Flat membranous sacs in stroma
$(d)$ Chromatin	$(iv)$ Infoldings in mitochondria

Given below are two statements:
Statement $I$: Mitochondria and chloroplasts are both double-membrane-bound organelles.
Statement $II$: The inner membrane of mitochondria is relatively more permeable compared to the inner membrane of chloroplasts.
In the light of the above statements,choose the most appropriate answer from the options given below:

The invention of the electron microscope led to a major breakthrough in the study of cells. What could be the reason for this?