Purple sulphur bacteria are

Which of the following organisms derives energy for $N_2$ fixation through photosynthesis?

Which of the following options shows the characteristics of $Mycoplasma$?

Which of the following is a characteristic of thermoacidophiles?

Choose the correct names of the different bacteria according to their shapes.

The nucleotide sequence in ribosomal $RNA$ provides the best evidence for the phylogeny of Monera. Based on this information,which are the most primitive Monerans?