Which of the following statements is correct?
$I.$ In a population,birth rate and death rate refer to per capita births and deaths,respectively.
$II.$ In nature,we rarely find isolated single individuals of any species.
$III.$ The size of a population for any species is a stable phenomenon.
$IV.$ Ecological effects of any factors on population growth are generally reflected in its size/population density.

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$(a)$ Allen's Rule	$(i)$ Kangaroo rat
$(b)$ Physiological adaptation	$(ii)$ Desert lizard
$(c)$ Behavioural adaptation	$(iii)$ Marine fish at depth
$(d)$ Biochemical adaptation	$(iv)$ Polar seal

Choose the correct answer from the options given below.

Consider the following statements $(A-D)$ each with one or two blanks.
$(A)$ Bears go into $ . . . . . . (1) . . . . . . $ during winter to $ . . . . . . (2) . . . . . . $ cold weather.
$(B)$ $A$ conical age pyramid with a broad base represents $ . . . . . . (3) . . . . . . $ human population.
$(C)$ $A$ wasp pollinating a fig flower is an example of $ . . . . . . (4) . . . . . . $.
$(D)$ An area with high levels of species richness is known as $ . . . . . . (5) . . . . . . $.
Which one of the following options gives the correct fill-ups for the respective blank numbers from $(1)$ to $(5)$ in the statements?

Match the following and select the correct option.

$A.$ Earthworm	$(i)$ Pioneer species
$B.$ Succession	$(ii)$ Detritivore
$C.$ Ecosystem service	$(iii)$ Natality
$D.$ Population growth	$(iv)$ Pollination

$A$ country with a high rate of population growth took measures to reduce it. The figure below shows age-sex pyramids of populations $A$ and $B$ twenty years apart. Select the correct interpretation about them.

Match List $I$ with List $II$.

$A$. Natality	$I$. $\frac{dN}{dt} = rN$
$B$. Exponential growth	$II$. Death rate
$C$. Mortality	$III$. Birth rate
$D$. Logistic growth	$IV$. $\frac{dN}{dt} = rN \left[1 - \frac{N}{K}\right]$