$Ectocarpus$ is:

From which of the following algae,agar-agar is commercially extracted?
$I.$ Gracilaria $II.$ Fucus $III.$ Sargassum $IV.$ Gelidium $V.$ Turbinaria

Read the following statements and identify the characters related to the alga shown in the diagram:
$(a)$ It is a member of Chlorophyceae
$(b)$ Food is stored in the form of starch
$(c)$ It is a monoecious plant showing oogonium and antheridium
$(d)$ Food is stored in the form of laminarin or mannitol
$(e)$ It shows dominance of pigments chlorophyll $a, c$ and Fucoxanthin.
Choose the correct answer from the options given below:

Which of the following can be used as a bacteriological filter?

The Indian species of $Spirogyra$ in which Prof. Iyengar discovered direct lateral conjugation is:

What is $Chlamydomonas$?