Question

Protonema is a characteristic of -

• A. Ulothrix
• B. Polytrichum
• C. Polysiphonia
• D. Marchantia

Hint:

Protonema is characteristic of mosses such as Funaria and Polytrichum. It develops from spores and later forms the leafy gametophyte.

Answer 1

The Correct Option is B

Concept: Bryophytes exhibit a distinct life cycle involving a gametophytic stage and a sporophytic stage. In mosses, spores germinate to form a green, filamentous structure known as protonema. This protonema subsequently develops into the mature leafy gametophyte. Therefore, protonema is a characteristic stage in the life cycle of mosses.

Step 1: Understand what protonema is. Protonema is a branched, filamentous, green structure that develops from the germination of a moss spore. It represents the juvenile stage of the gametophyte.

Step 2: Examine the options. Ulothrix is a green alga and does not possess a protonema stage. Polytrichum is a moss and exhibits a well-developed protonema stage. Polysiphonia is a red alga and lacks protonema. Marchantia is a liverwort; the characteristic protonema stage is associated with mosses rather than liverworts.

Step 3: Draw the conclusion. Among the given options, Polytrichum shows a protonema stage. \[ \boxed{\text{Polytrichum}} \] Hence, the correct answer is \[ \boxed{(B)\ \text{Polytrichum}} \]