The antibiotic "chlorellin" is extracted from which genus?

The structure of Floridean starch is similar to:

During rainy seasons,the ground becomes slippery due to dense growth of

Select the correct option for the given plant.

In $Ulothrix$,$Spirogyra$,and $Chlamydomonas$,at what stage does meiosis occur?

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