Which of the following is an exception in terms of its life cycle?

Cells of $Spirogyra$ are

The zoospores of $Ulothrix$ are liberated by:

Read the following statements and choose the set of correct statements: In the members of Phaeophyceae,
$A$. Asexual reproduction occurs usually by biflagellate zoospores.
$B$. Sexual reproduction is by oogamous method only.
$C$. Stored food is in the form of carbohydrates which is either mannitol or laminarin.
$D$. The major pigments found are chlorophyll $a$,$c$ and carotenoids and xanthophyll.
$E$. Vegetative cells have a cellulosic wall,usually covered on the outside by gelatinous coating of algin.
Choose the correct answer from the options given below:

Which of the following algae is symbiotic and nitrogen-fixing?

Which of the following is known as pond silk?