Question

Ciliates differ from all other protozoans in
A. Using pseudopodia for capturing prey
B. Using flagella for locomotion
C. Having two types of nuclei
D. Having a contractile vacuole for removing excess water

Answer 1

Hint: Ciliates differ from other protozoans regarding one of the structures of eukaryotic cells, it was first observed by Anton Van Leeuwenhoek. It was discovered by Robert Brown in an orchid's root cell.

Complete answer:
The ciliates differ from other protozoans in having two nuclei which are also distinct from each other. There is a smaller nucleus known as micronucleus and larger nuclei known as macronucleus. This type of nucleus is called a dimorphic nucleus.

Additional Information:
Other features of class Ciliata under phylum protozoa are:
- The presence of a pellicle is seen in ciliates.
- Locomotion in cilia occurs with the help of the cilia and suctorial tentacles, seen in at least one phase of their life cycle.
- Holozoic type of nutrition is observed.
- They reproduce asexually by binary fission.
- Conjugation and autogamy are modes of sexual reproduction.

Some features of phylum protozoa are:
- They are microscopic mostly and unicellular, but some are large and can be seen with naked eyes.
- At the cellular level, the division of labor is seen.
- No cell organelles are found, the nucleus can be more than one in number.
- Ecological interactions like mutualism, commensalism, and parasitism are shown by these organisms.
- Locomotory organs include cilia, flagella, pseudopodia. Some of the protozoans are sessile.

So, the correct answer is, “Ciliates differ from all other protozoans by having two types of nuclei.”

Note: It is important to know that ciliates show active locomotion and movement due to the presence of thousands of hair-like projections known as cilia. They also have a cavity known as gullet that opens outside their body surface. Cilia not only helps in movement but due to its active motion, it is able to direct the water consisting of food towards the gullet.