This microbe is photosynthetic, but in the absence of light it can use organic compounds as an energy source. Its carbon source is an organic compound. The appropriate classi?cation for this organism would be ______.
A) chemoautotroph B) photoheterotroph C) lithotroph D) photoautotroph
The methanogens, producers of methane gas, require environments that _______.
A) are extremely cold B) are very acidic C) have abundant oxygen and CO₂ D) are directly exposed to sunlight E) are anaerobic with hydrogen gas and CO₂