NTA Abhyas NEET2020BotanyBiological ClassificationPractice
Select the CORRECT statement/s regarding heterocysts.
Options
- AThese are present in some filamentous cyanobacteria such as Nostoc and Anabaena .
- BThese cells are specialized to perform N 2 -fixation.
- CThese cells contain enzyme nitrogenase.
- DAll of these
Correct answer
D. All of these
Step-by-step solution
Specialized nitrogen-fixing cells found in some filamentous cyanobacteria are called heterocyst. These are modified to fix atmospheric nitrogen when faced with nitrogen starvation. Heterocyst contains the enzyme nitrogenase which helps in fixing N 2 and provides nitrogen for cell biosynthesis. Since nitrogenase gets deactivated in the presence of oxygen, the heterocyst creates a micro-anaerobic environment. These cells undergo certain physiological changes like the presence of three additional cell walls, degradati