Which of the following levels is not conceptual in terms of size?

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.

Which major biome of India is represented in the given figure?

$A$ 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.

Read the given statements and identify the correct and incorrect ones.
$(1)$ The exponential growth curve can be calculated using the formula $N_t = N_0 e^{rt}$.
$(2)$ Bamboo and salmon fish show the production of offspring only once during their entire lifespan.
$(3)$ In the amensalism type of interaction,one species is harmed and the other species receives no benefit or harm.
$(4)$ $A$ competitively superior species eliminates the inferior species in a habitat.

Match the columns:

Column-$I$	Column-$II$
$(a)$ Cacti	$(i)$ Leguminous plants
$(b)$ Shade loving plants	$(ii)$ Commensalism
$(c)$ Halophytes	$(iii)$ Pioneer community
$(d)$ Crustose lichen	$(iv)$ Plants growing in saline environment
$(e)$ Interspecific interaction	$(v)$ Xerophytes
$(f)$ Rhizobium	$(vi)$ Sciophytes