The technique of obtaining a large number of plantlets by tissue culture method is called:

$A$ student is allowed to select at most $n$ books from a collection of $(2n + 1)$ books. If the number of ways to select at least one book is $63$,then the value of $n$ is:

Which one of the following is not used for the construction of ecological pyramids?

Which part of the tobacco plant is infected by the nematode $Meloidogyne \ incognita$?

The classification of organisms into prokaryotes and eukaryotes is based on which characteristic?

Which of the following is the most basic oxide?