There are several ways of looking at living things. One way,which is at the molecular and analytical level with regard to life,could be described as:

Which of the following two are known as the twin characteristics of growth?
$(i)$ Irreversible increase in mass $(ii)$ Uncontrolled $\&$ Repeated Cell Division $(iii)$ Increase in number of individuals $(iv)$ Reproduction

Biologists focus on which aspect to identify a living organism?

Metabolism is a defining feature of all living organisms without exception. Isolated metabolic reactions in vitro are not living things but surely living reactions. Comment.

Match Column-$I$ (Scale) with Column-$II$ (Biological entity) and select the correct option:
| Column-$I$ (Scale) | Column-$II$ (Biological entity) |
| :--- | :--- |
| $(a)$ Macroscopic | $(i)$ Cells |
| $(b)$ Microscopic | (ii) Organisms |
| $(c)$ Sub-microscopic | (iii) Society |
| $(d)$ Conceptual | (iv) Atoms |

Assertion: Living organisms are regarded as closed systems.
Reason: Energy of living organisms cannot be lost or gained from the external environment.