Assertion $(A)$: Algae are found in various colors.
Reason $(R)$: Algae contain different types of pigments.

Which of the following types of algae is most likely to be found in the deepest waters?

The basal cell of $Ulothrix$ is:

Select the correct option for the cell wall of green algae.

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?

Spirogyra cells contain