Question

In fern plant, the ejection of spores with force is achieved by the
a. Sporangiospore
b. Annulus
c. Stomium
d. Indusium

Answer 1

Hint: Ferns are a group of vascular plants that reproduce by germination of spores in the environment. They have a specialized cell for the conduction of water and nutrients in the body, this tissue helps in the ejection of spores also, spores are ejected from the same pathway from where extra water is ejected.

Complete answer:
The annulus is the ring-like structure such as superficial rings present on blood-sucking leech
- It is a row of cells with both thin and thickened cell walls which facilitate the opening of sporangia and release of the spores
- It is an unequal expansion and certain tension is produces as they are moistened and dried
- The thinner walls on the out of doors permit water to evaporate quickly underneath dry conditions.
- This dehiscence causes the cells to cut back and a contraction and straightening of the annulus ring, finally rupturing the sporangial wall by means of ripping aside thin-walled tip cells on the alternative facet of the sporangium.
- As extra water evaporates, air bubbles form in the cells inflicting the shrivelled annulus to snap forward again, therefore dislodging and launching the spores far from the plant.
- The kind and role of the annulus are variable (e.G. Patch, apical, indirect, or vertical) and can be used to differentiate predominant businesses of leptosporangiate ferns.

Hence, the correct answer is option (B).

Note: Fern spores are contained in sporangia which are borne on the leaf surface in clusters and are called sori. Sori is present in nature in all shapes and sizes with different locations on a fern, they can be dots, dashes, or simple lines. Annulus undergoes hygroscopic movements causing sporangium to break.