Which of the following two groups of extremophiles grow in highly acidic habitats $(pH = 2)$?

Select the correct option for the following matches:

$(1)$ Gram-positive bacteria	$(a)$ Thermoacidophiles
$(2)$ Bacteria living in acidic medium	$(b)$ Firmicutes
$(3)$ Gram-negative bacteria	$(c)$ Halophiles
$(4)$ Bacteria living in extreme salty conditions	$(d)$ Spirochetes

There is no alternation of generation in $Escherichia$ $coli$ because of the absence of

The cell wall of Gram-negative bacteria is:

Cyanobacteria and heterotrophic bacteria have been clubbed together in eubacteria of kingdom-Monera as per the "five kingdom classification", even though the two are vastly different from each other. Is this grouping of the two types of taxa in the same kingdom justified? If so, why? Discuss the cellular composition of cyanobacteria and heterotrophic bacteria that make them classified as eubacteria.

Blue-green algae (Cyanobacteria) contain which type of chlorophyll?