Question

Organelles of offence and defence in Paramecia are …………
A.Trichocysts
B.Nematocysts
C.Cilia
D.Kinetosomes

Answer 1

Hint:Paramecia are single-celled protists that are naturally found in aquatic habitats. They are mostly oblong or slipper-shaped and are covered with short hair-like structures called cilia. Some paramecia are easily cultured in labs and serve as model organisms.

Complete answer:
(A) Trichocyst, it is a structure in the cortex of certain ciliates and flagellate protozoans which contains a cavity and long, thin thread-like structures that can be ejected in response to certain stimuli. one of the most important functions of trichocysts is to defend and attack the enemy.
(B) Nematocysts are found in the phylum Cnidaria, which includes jellyfishes and sea anemone and it is also called cnidocyte or cnidoblast, these are specialized cells found in the tentacles of jellyfish which are capable of projecting a thread-like structure which helps in self-defense or to capture prey.
(C) Cilia perform important functions in the life of Paramecium, such as locomotion through the surrounding water and ingestion of food into the cytostome which is present in the body. These are responsible for the ingestion of food and also they help in the localization of the gullet which is a funnel-shaped depression on the cell surface.
(D) At the level of the plasma membrane, the proximal end of the cilium is continuous with its tube-shaped basal body or kinetosome. The peripheral filaments of the cilium, together with the material of cortical matrix which tend to condense around them, form the sheath of the basal body.
Hence, the correct option is (A) Trichocysts.

Note:There are several types of trichocyst like Mucoid trichocyst and Filamentous trichocysts. The Mucoid trichocyst is elongated inclusions which are ejected as visible bodies after artificial stimulation. The other type of trichocyst is Filamentous trichocysts in Paramecium and other ciliates are discharged as filaments composed of a cross-striated shaft and a tip.