Plants require different minerals because......

Select the correct match for $X$ and $Y$:

Column $X$	Column $Y$
$(1)$ Mycorrhiza	$(P)$ Free-living $N_2$-fixer
$(2)$ Nostoc	$(Q)$ Phosphorus absorption
$(3)$ Azospirillum	$(R)$ Leguminous plants
$(4)$ Rhizobium	$(S)$ Autotrophic $N_2$-fixer

The agent/s which make/s free atmospheric nitrogen available to plants is/are:

Select the correct option:
$(1)$ During $transamination$ / $reductive$ $amination$,an amino group is transferred from one amino acid to the keto group of a keto acid.
$(2)$ $Azotobacter$ / $Clostridium$ are free-living bacteria.

Name a plant which accumulates silicon.

Choose the incorrect sentence.