An example of mutualism is

Viruses are considered as a link between living and non-living organisms because -

In lichens,sexual reproduction belongs to

Lichens grow at a very slow rate ($1 mm$ per year). In how many years does a lichen mature?

Choose the correct option for the following statements:
$(i)$ The name virus,meaning venom or poisonous fluid,was given by $Pasteur / D. J. Ivanowsky$.
$(ii)$ $W. M. Stanley / T. O. Diener$ discovered viroids.

Infectious proteins are present in