Which of the following is known as the primitive plant?

In $Chlamydomonas$,the meiosis occurs in:

The most common asexual structure produced in algae is:

Mannitol is the stored food in $..........$.

Which of the following statements are applicable to brown algae?
$(I)$ They contain pigments like chlorophyll $a$,chlorophyll $c$,carotenoids,and xanthophylls.
$(II)$ They vary in color from olive green to various shades of brown.
$(III)$ Food is stored as complex carbohydrates,in the form of laminarin or mannitol.
$(IV)$ The cell wall is composed of cellulose and algin.
$(V)$ The cell wall is covered on the outside by a gelatinous coating of algin.

Sexual reproduction in algae results in the formation of