Question

Diaplantism is exhibited by?
A. Saprolegnia
B. Rhizopus
C. Ulothrix
D. Vaucheria

Answer 1

Hint:
Diplanetism is a phenomenon. It has two mobile stages with a pause between them. For instance, Saprolegnia releases a zoospore that forms a cyst right away. But this will germinate at some later time to release its secondary zoospore. Hence Saprolegnia exhibits Diaplantism.

Complete answer:
Option A i.e Saprolegnia is a genus of water molds often called cotton moulds. It has a characteristic feature that is the presence of white or grey fibrous patches they form. According to the Current taxonomy, Saprolegnia belongs to a genus of the heterokonts. It is in the order of Saprolegniales.
Option B is rhizopus. It is a genus of saprophytic fungi on plants. This is the most common. It is also present in the form of specialized parasites on animals. They are found in a wide variety of organic substances like mature fruits and vegetables, peanuts, jellies, syrups, leather, bread, and tobacco. They are multicellular.
Option C is Ulothrix belonging to the genus of non-branching filamentous green algae. It is generally found in fresh and marine water. They survive in the low temperatures of spring and winter. They attach to all surfaces by a modified holdfast cell. The reproduction exhibited by them is normally vegetative.
Option D is Vaucheria, it belongs to the genus of Xanthophyceae or yellow-green algae. It is among the two genera in family Vaucheriaceae. It exhibits apical growth. This occurs from the tip of filaments forming mats in either terrestrial or freshwater environments.

So, the correct answer option A i.e Saprolegnia.

Note: The phenomenon of vigilantism is observed in many members of the Oomycetes. It shows two distinct motile phases and morphologically different zoospores are formed in each.