Question

6. What organism were the first oxygen-evolving phototrophic organisms on Earth, and over billions of years converted the once anoxic atmosphere of Earth to the to the oxygenated atmosphere we see today?

7. What doe purple sulfur bacteria use as an electron donor for photosynthesis?

8. What is the genus of the bacteria that is curved and highly motile that feeds as a collective on other bacteria? (Clue: prefix of its name means “leech”). __________________________________

9. What spirochete is the causal agent of syphilis? ________________________________________________

10. What enzyme is responsible for bioluminescence in bacteria?

Answer 1

6. Cyanobacteria.

• Early form of bacteria are Cyanobacteria, like Oscillatoria.
• Cyanobacteria are phototrophic and aerobic organisms.
• As per the endosymbiotic theory, engulfment of phototrophs formed chloroplast.
• Thus, Cuanobacteria adapted to anaerobic environments and further existed as organelle in higher phototrophs.

7. Hydrogen sulfide

• Electrons may be obtained from chemical, by lithotrophs and from organic sources by organotrophs.
• Purple sulfur bacteria use Hydrogen sulfide as electron source, during photosynthesis.
• Thus, they are chemoautotrophs.

8. Bdellovibrio

• Bdellovibrio are genus of bacteria that can exist in other bacteria (host bacteria may be Coliforms, like Pseudomonas, Salmonella).
• Bdellovibrio are Gram negative, aerobic, motile and curved bacteria.
• They can feed on biopolymers.

9. Treponema pallidum

• Spirochetes: Treponema pallidum causes Syphilis

10. Luciferase

• Luciferase is an enzyme that are produced by several organisms.
• Luciferase results in oxidation of luciferin to cause bioluminescence.