Question

What is the life cycle of Paramecium?

Answer 1

Paramecium:

1. Paramecium or Paramoecium is a genus of unicellular ciliated protozoa.
2. They are characterized by the presence of thousands of cilia covering their body.
3. They are found in freshwater, marine and brackish water and are also found attached to the surface.

Life cycle of Paramecium has asexual and sexual stages.

1.Asexual stage:

1. Asexual reproduction in paramecium is by binary fission.
2. The mature cell divides into two cells and each grows rapidly and develops into new organism. Under favorable conditions.
3. Paramecium multiplies rapidly up to three times a day.

2.Sexual stage:

1. Sexual reproduction in Paramecium takes place only when there is scarcity of food.
2. Sexual reproduction is by Conjugation or Autogamy.
3. In conjugation, two complementary paramecia come together and form the conjugation bridge. United paramecia are known as conjugants.
4. Macronuclei of both the cells disappear. The micronucleus of each conjugant form 4 haploid nuclei by meiosis.
5. Three of them nuclei degenerate. The haploid nuclei of each conjugant then fuse together to form diploid micronuclei and cross fertilization takes place resulting in formation of new daughter cells.
6. In Autogamy i.e., self fertilization, a new macronucleus is produced which increases their vitality and rejuvenates them.