Which of the following cells does not contain a nuclear membrane?

Assertion $A$: Bacillus and Coccus types of bacteria are found in colonial forms.
Reason $R$: In bacteria,cells formed by cell division remain surrounded by a secreted mucilaginous substance.
Which option is correct for Assertion $A$ and Reason $R$?

Pili in bacteria represent

Which of the following is not true for the heterocyst of $Nostoc$?

Which of the following kingdoms consists of organisms that lack a well-defined nucleus?

Match the organisms in Column-$I$ with habitats in Column-$II$.

Column-$I$	Column-$II$
$(a)$ Halophiles	$(i)$ Hot springs
$(b)$ Thermoacidophiles	$(ii)$ Aquatic environment
$(c)$ Methanogens	$(iii)$ Guts of ruminants
$(d)$ Cyanobacteria	$(iv)$ Salty area

Select the correct answer from the options given below: