Question

A ciliate, which is commonly used as an experimental organism is
A. Vorticella
B. Balantidium
C. Tetrahymena
D. Paramecium

Answer 1

Hint: Ciliates are sets of characterized protozoans. Cilia are hair-like organelles, which are similar in form to eukaryotic flagella but are normally shorter and are present in much larger numbers, with a distinct modulation pattern of flagella. They are free-living ciliates used commonly as experimental organisms.

Complete answer: Ciliated protozoa are single-celled species that have cilia, short hair-like structures used for locomotion and to collect food at some point in their life cycle. Generally, cilia are arranged in rows. On the pellicle, however, some species of undulating membranes can fuse together near the cytostome. Flexible pellicles, contractile vacuoles, trichocysts and small organelles are found in most ciliates. The first protozoan to be axenically grown was Tetrahymena pyriformis, in the absence of other creatures. Tetrahymena is a free-living ciliate genus that can also switch from survival modes that are commensalism to pathogenic. Tetrahymena species are used in biomedical research as model organisms. The life cycle of Tetrahymena involves an alternation between periods of asexual and sexual activity. In a nutrient-rich media, cells replicate asexually by binary fission. This form of cell division occurs through a series of morphogenetic events that results in the formation of duplicate sets of cell structures. Cells commit to sexual conjugation, pair and fuse with a cell of the opposite mating type only under starvation conditions. There are seven forms of mating in Tetrahymena; each can match any of the other six without preference.
So, option C is the correct answer.

Note: Free swimming cells of Tetrahymena are attracted to certain chemicals by a process called chemokinesis. Some of the major chemoattractants are peptides and proteins. They have the capacity to learn the shape and size of their swimming space.