Which of the following statements is $NOT$ correct?

The main difference between living and non-living things is:

Two plants can be concluded to belong to the same species if they:

The distance between stars is measured in . . . . . . .

Define the following terms:
$(i)$ Unicellular organism
$(ii)$ Multicellular organism

Which of the following statements are correct regarding the characteristics of living organisms?
$I$. $DNA$ molecules are inherited by organisms produced by parents.
$II$. Organisms adapt to their habitat by considering environmental factors.
$III$. Complex energy transformations in metabolism are not essential for living organisms.
$IV$. Morphogenesis occurs during the process of development.