Question

Assertion:
Antherozoids of Funaria show chemotropic movement.
Reason:
This is a paratonic movement of locomotion.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Assertion is incorrect but the reason is correct.

Answer 1

Genus Funaria is the terrestrial moss (bryophytes). Antherozoids are the male gametophyte produced in a plant. Chemotropic movement of any plant part is a movement in response to a chemical stimulus.

Complete answer:
Bryophytes are non-vascular plants that do not have vascular tissues and are short in size. Funaria belongs to the class Bryopsida. The body of moss is thallus-like, prostrate, or erect. It is attached to the substratum by unicellular or multicellular rhizoids. They lack true roots, stem, or leaves, however, they may possess root-like or stem-like structures. They grow in clumps or mats and often in shady locations. The life cycle of moss has gametophyte as the predominant stage which consists of two stages. Protonema (juvenile gametophyte) and the leafy stage.
In the protonema stage, the plant develops directly from a spore. It is a branched, and filamentous stage. In the leafy stage, the plant develops from the secondary protonema as a lateral part. They consist of upright, spirally arranged leaves. They are attached to the soil through rhizoids that are multicellular and branched. This stage bears sex organs. The sex organs are multicellular, male sex organ is called antheridium that produces many biflagellate antherozoids. The female sex organ is called Archegonium that produces a single egg. The antherozoids are then released into the water which then swims towards archegonium and comes in contact with the egg to produce a zygote.
The antherozoid that is male sperm is attracted towards female archegonium by the canal cells in archegonium that secrets malic acid and sugar. This movement is known as the chemotropic movement as it is induced by chemicals secreted by female gamete. Paratonic movement, on the other hand, is the movement of a plant or part of the plant due to external stimuli like gravity, heat, chemicals, etc.

Hence, the correct option will be option B - Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

Note: Bryophytes are also known as amphibians of the plant kingdom as they can live on soil but are dependent on water for sexual reproduction. Canal cells present on the neck of archegonium also secrets mucilage a slimy liquid for passage of sperm.