In brown algae,asexual reproduction occurs primarily through:

The cell wall of $Spirogyra$ is made up of

Assertion : Red algae contribute to the production of coral reefs.
Reason : Some red algae secrete and deposit calcium carbonate over their walls.

In which members of algae is the formation of zoospores not observed?

The unique feature of Thallophyta is .........

Which of the following organisms cannot fix nitrogen?
$A.$ Azotobacter
$B.$ Oscillatoria
$C.$ Anabaena
$D.$ Volvox
$E.$ Nostoc
Choose the correct answer from the options given below: