Question

Movement in peristome teeth of moss is
(a) Hydrochasy
(b) Xerochasy
(c) Chemotactic
(d) Chemotropism

Answer 1

Hint The movement in plants has been observed under the influence of various biological factors such as sugars as well as physical factors like water. The movement in peristome teeth of moss is required for the dispersal of spores.

Complete answer:
Moss is included under the division Bryophyta. The main plant body of a bryophyte is a dominant, independent, photosynthetic, and haploid gametophyte. It alternates with a short-lived multicellular sporophyte which is totally or partially dependent on the gametophyte. The sporophyte is distinguished by the presence of characteristic divisions in the plant body where it is divided into a foot, seta, and capsule. In the capsule, there are teeth-like structures known as peristomes which are specialized in the function of spore dispersal from the sporangium. These peristomes open via xerochasy. It is a type of physical movement in plants wherein the walls of the capsule lose water in dry weather conditions. Losing water induces the gradual opening of capsules by the movement of peristomes due to their contraction in size.

Additional Information:
-The peristomal teeth thickens and swells in the presence of water i.e when they are wet. This movement of plant structures upon absorption of water is known as hydrochasy.
-Chemotactic movements refer to the movement of plant parts under the influence of chemicals. Like antherozoids of bryophytes in the direction of sugars released by the neck canal cells of archegonia.
-Chemotropism is the growth of plants or their parts towards chemical stimuli. Like a pollen tube growing through the long style due to their attraction by the chemicals produced by synergid cells.

So, the correct answer is ‘Xerochasy.’

Note:
-The gametophytic plant body is radially symmetrical with a branched axis, on which the leaves are radially arranged.
-On its main axis, the male reproductive structure ‘antheridia’ is present while on its lateral branches, archegonia or the female reproductive organ is located.