Question

Common between trichocyst of Paramecium and nematocyst of Hydra is:
A. Attachment and defense
B. Defense only
C. Sensitivity
D. Food capturing

Answer 1

Hint: Paramecium is a protozoan while Hydra is a cnidarian. Both of these organisms have specialized structures called trichocyst in Paramecium and nematocyst in Hydra for offense and defense. Structurally both the trichocysts and nematocysts are different but they serve a common function. Trichocysts and nematocysts help to prevent predation.

Complete answer:
Option A: In this option ‘attachment and defense’, only the term defense can be considered correct as both trichocysts and nematocysts help in defense against predation.
Thus, this option is incorrect.
Option B: This option seems more correct as it states that both the nematocysts and trichocysts serve the function of defense. This is a fact.
Thus, Option: B is correct.
Option C: Sensitivity is not the function of nematocysts or trichocysts so this is an incorrect point. Cnidarians have sensory cells for sensory functions while protozoans like Paramecium have statocyst for sense.
Thus, this option is incorrect.
Option D: Food capturing is again not a function of nematocysts and trichocysts so, this is also the wrong point.
Thus, this option is also not correct.

Therefore, Option B is the correct answer.

Note:
Trichocyst is a structure in the cortex of certain ciliated and flagellated protists. Trichocysts consists of a cavity and long, thin threads that can be expelled in response to certain stimuli as an action of defense, Nematocysts or Cnidoblasts are stinging organs present in the invertebrate organisms of the phylum Cnidaria and consists of a capsule, shaft and a thread tube. It is generally used for defense and offense.