Heterocysts are large sized, thick-walled specialised cells which occur in terminal, intercalary or lateral position in filamentous cyanobacteria, e.g., Nostoc. They have enzyme nitrogenase and are specialised to perform biological nitrogen fixation.

Correct Option: B

Heterocysts are large sized, thick-walled specialised cells which occur in terminal, intercalary or lateral position in filamentous cyanobacteria, e.g., Nostoc. They have enzyme nitrogenase and are specialised to perform biological nitrogen fixation.

Archaebactera live in some of the most harsh habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens) and in deep sea water.

Correct Option: D

Archaebactera live in some of the most harsh habitats such as extreme salty areas (halophiles), hot springs (thermoacidophiles) and marshy areas (methanogens) and in deep sea water.

Motile bacteria have thin filamentous extensions on their cell wall called flagella.

Correct Option: B

Motile bacteria have thin filamentous extensions on their cell wall called flagella.

Fimbriae assist some bacteria in attaching to rocks or host body for obtaining establishment and nutrition.

Correct Option: A

Fimbriae assist some bacteria in attaching to rocks or host body for obtaining establishment and nutrition.

Mycoplasmas are smallest, prokaryotes lacking cell wall and are pleomorphic in nature. These are pathogenic to both plants and animals.

Correct Option: B

Mycoplasmas are smallest, prokaryotes lacking cell wall and are pleomorphic in nature. These are pathogenic to both plants and animals.