The non-motile,greatly thickened asexual spores are called

Sexual reproduction in which cells of two different $Spirogyra$ filaments conjugate is known as

Which one of the following is an example of a chlorophyllous thallophyte?

Consider the following statements:
$I$. They reproduce asexually by non-motile spores and sexually by non-motile gametes.
$II$. In this class,sexual reproduction is oogamous and accompanied by complex post-fertilisation developments.
$III$. The common members are $Polysiphonia$,$Porphyra$,$Gracilaria$ and $Gelidium$.
The above characteristics belong to which class of algae?

The stored food in Polysiphonia is:

Algin is a phycocolloid,obtained from the cell wall of