Question

What is the characteristic branching pattern of Dictyota thallus?
A. Monopodial
B. Excurrent
C. Dichotomous
D. Deliquescent

Answer 1

Hint: The plant body of algae is called thallus. The thallus of algae shows a great variety of forms. The multicellular forms may be palmelloid (aggregate of cells having no fixed number), coenobium (colonial having fixed number), dendroid (colonial tree-shaped) siphonaceous (coenocytic), filamentous of foliaceous (a sheet of cells). Some of the foliaceous forms are complex and very large in size up to 60 meters in length.

Complete answer:
Dictyota belongs to brown algae (Phaeophyta). They grow in tidal and subtidal regions of colder seas. However, ectocarpales, dictyotales, and sargassum species grow in warm waters. There are no cellular, colonial or unbranched filamentous forms in brown algae. The thallus organization in brown algae include branched filamentous heterotrichous forms ( e.g. Ectocarpus), multiaxial construction forms (eg. Myriactula pulvania), uniaxial pseudoparenchymatous forms (e.g. Hecatonema), parenchymatous forms (e.g. laminaria, fucus). Besides some forms appear like miniature trees (e.g. Lessonia flavicans). The plants of Postelsia palmaeformis appear like palm trees, commonly called sea palm. Dictoyota is a branched filamentous heterotrichous ribbon-shaped alga. Its front is flat and dichotomously branched.
So, the correct answer is option C, i.e., Dichotomous.

Note: The plant body of some highly advanced forms is differentiated into basal more or less root-like holdfast erect branched or unbranched, tubular or compressed stipe, and leaf-like blades. Alternation of generation is isomorphic (e.g. Dictyota). Sexual reproduction is oogamous in Dictyota.