Sex organs of thallophytes are generally

In $Gracilaria$,sexual reproduction is

The thallus organisation of $Volvox$ is

Read carefully the given statements about algae and choose the correct option.
$I$. The plant body is thalloid.
$II$. Mainly aquatic.
$III$. Reproduction takes place by vegetative,asexual,and sexual methods.
$IV$. Volvox and Ulothrix are the colonial forms of algae.

In Rhodophyceae,stored food is available as:

In Thallophyta,embryo formation does not occur because: