Question

How many organisms in the list given below are autotrophs?

Lactobacillus, Nostoc, Chara, Nitrosomonas, Nitrobacter, Streptomyces, Sacharomyces, Trypanosoma, Porphyra, Wolfia

• A. Five
• B. Six
• C. Three
• D. Four

Answer 1

Answer: (B)

Six

• Autotrophic bacteria synthesize their cell constituents using carbon dioxide as the carbon source.
• From the list, autotrophic bacteria include a total of six as Chara, Nostoc, Porphyra, Wolfia, Nitrosomonas, Nitrobacter. Of these Chara, Nostoc, Porphyra, Wolfia is photoautotrophs while Nitrosomonas, Nitrobacter are chemoautotrophs.
• The other four (Lactobacillus, Streptomyces, Saccharomyces, Trypanosoma) are heterotrophs meaning they utilize organic compounds as a source of food.

Thus, the correct answer is option B.