NEET BIOLOGY

Detailed explanation-1: -Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc punctiforme, Cylindrospermum stagnale, and Anabaena sphaerica.

Detailed explanation-2: -Thus, the correct answer is ‘Nitrogen fixation.

Detailed explanation-3: -A Heterocyst is a transparent thick-walled empty cell seen in blue-green algae filaments at an intermittent position. Heterocysts are nitrogen-fixing cells generated by certain filamentous cyanobacteria, such as Nostoc punctiforme, Cylindrospermum stagnale, and Anabaena sphaerica, under nitrogen shortage.

Detailed explanation-4: -The main function of heterocyst is to fix nitrogen. Examples of blue-green algae containing heterocysts are Nostoc punctiforme, Cylindrospermum stagnale, and Anabaena sphaerica.

Detailed explanation-5: -1. Heterocysts are found in many species of filamentous blue-green algae. They are cells of slightly larger size and with a more thickened wall than the vegetative cells.