Based on the levels of biological organization,what does the part labeled "$P$" indicate in the branches of science?

What are '$X$' and '$Y$' in the given figure?

Match the following columns:

Column-$I$	Column-$II$
$a.$ Binomial nomenclature	$(i)$ Carolus Linnaeus
$b.$ Generic name	$(ii)$ Muscidae
$c.$ Family	$(iii)$ Panthera
$d.$ Systema naturae

Match Column $X$ with Column $Y$ and select the correct option:

Column $X$	Column $Y$
$(1)$ Population	$(P)$ Group of closely related species
$(2)$ Differentiation	$(Q)$ Result of metabolism
$(3)$ Family	$(R)$ Energy available for any system's work
$(4)$ Growth	$(S)$ Formed by individual organisms
$(5)$ Potential energy	$(T)$ Change in embryonic cells according to their specific functions

Match the items in Column-$I$ with those in Column-$II$:
| Column-$I$ (Subject) | Column-$II$ (Science) |
| :--- | :--- |
| $(a)$ Tissue | $(i)$ Ecology |
| $(b)$ Atoms | (ii) Biology |
| $(c)$ Species | (iii) Physics |
| $(d)$ Organisms | (iv) Cytology |

What does '$X$' represent in the given figure?