Question

Trichocysts occur in
(a) Liver fluke
(b) Bladder worm
(c) Paramecium
(d) Hydra

Answer 1

Hint: A unicellular organism commonly called a slipper animalcule that belongs to the phylum Ciliophora which reproduces by transverse binary fission consisting of long flagella.

Complete answer:
Thin thread-like structures that are ejected out in response to certain stimuli are called trichocysts. They can be restricted only at certain places of the body like around the mouth, tentacles, and papillae or can be spread widely around the body. Trichocysts are found in tetrahymena and the cilia pathway in several metabolic pathways. The cavities of certain ciliates and flagellates like paramoecium contain trichocysts. In the conditions of threat by the predators, trichocysts are ejected from the cell surface and are used for defense.

Additional Information: - Trichocysts are of several types namely mucoid trichocysts, filamentous trichocysts, and toxicysts.
- After artificial stimulation, the elongated inclusions that may be ejected as visible bodies are called mucoid trichocysts.
- Discharged filaments composed of a cross-striated shaft and a tip seen in paramoecium and other ciliates are called filamentous trichocysts.
- Trichocysts that are localized around the mouth are called toxicysts. A long, nonstriated filament with a rod-like tip is discharged by toxocyst that helps to paralyze or kill other microorganisms. These are used as a defense and also used to capture the food.
So, the correct answer is ‘Paramecium’

Note: -Liver fluke and bladder worm belong to the phylum Platyhelminthes and hydra belongs to the phylum cnidaria in which trichomes are absent.
-Polyp and medusa are the two basic forms shown by the cnidarians. A polyp is cylindrical and sessile seen in hydra and medusa is an umbrella-shaped free-swimming form seen on jellyfish. In parasitic forms of the Platyhelminthes contain hooks and suckers.