Which of the following is a red alga that is not red?

Apart from chlorophyll,algae have several other pigments in their chloroplasts. Which pigments are found in blue-green algae $(BGA)$,red algae,and brown algae,that are responsible for their characteristic colours?

The basal cell of $Ulothrix$ is:

The study of algae is known as ........

How does asexual reproduction occur in $Spirogyra$?

Spermatia are the male gametes of ........