Which of the following is known as the primitive plant?

Provide the answers for the following analogy-based questions:
$(i)$ Flagellated : Zoospore :: Non-flagellated : ........
$(ii)$ Volvox : Colonial :: Spirogyra : .....

Isogamous condition with non-flagellated gametes is found in:

In Chlorophyceae,which type of sexual reproduction is observed?

Number of flagella present in the gametes of $Ulothrix$ is

Which of the following statements is true for algae?