Question

Spirochaetes are
A. A class of insects
B. A class of viruses
C. Bacteria
D. Fungi

Answer 1

Spirochaetes or Spirochetes are a group of spiral-shaped organisms that belongs to the kingdom Monera which are disease causing pathogens. They are chemoheterotrophic in nature.

Complete answer: Spirochetes are slender bacteria of varying length between 3 to 250 microns and diameter around $0.09$ to at least 3 microns. The spirochete is a member of the phylum spirochaetes. They are distinguished from the other bacterial phyla by their axial filament. The axial filament is rotated by the rotation of the flagella that causes the spirochete to move. A twisting motion allows the spirochaetes to move about. Moreover, they are thin shaped, tightly coiled and look like miniature springs or telephone cords. Some are free-living in the aquatic environment, while some can only survive by parasitizing the cells of other organisms. Most are anaerobic that can sustain themselves without oxygen, whereas some species are aerobic. Furthermore, they are not easily visible. Spirochetes can be found in the human oral cavity, the gastrointestinal tract of mammals, insects and in the marine environment. Spirochetal diseases occur in stages with an intervening latent period. Add to this, untreated infections may last in hosts from months to years. Moreover, endoflagella is a unique feature that allows them to move through viscous material in a multi-directional way.
Therefore, option C is the correct answer.

Note: Both Syphilis and Lyme diseases are caused by these bacteria. Most of the Spirochaetes or Spirochetes are characterized by their distinct shapes and unique motility. They are either free-living or host-associated. Examples of genera of spirochetes include Treponema , Borrelia , and Leptospira.