Q. How many organisms in the list given below are autotrophs ?
Lactobacillus, Nostoc, Chara, Nitrosomonas, Nitrobacter Streptomyces, Saccharomyces, Trypanosoma, Porphyra, Wolffia

 2240  208 AIPMTAIPMT 2012Plant Kingdom Report Error

Solution:

Autotrophic nutrition involves manufacture of organic materials from inorganic raw materials with the help of energy obtained from outside sources. It is of two types - chemosynthesis and photosynthesis. The organisms which are able to manufacture their organic food from inorganic raw materials with the help of energy derived from exergonic chemical reactions are called chemoautotrophs. Nitrosomonas and Nitrobacter are chemoautotrophic nitrifying bacteria. Those organisms who can manufacture organic compounds from inorganic raw materials with the help of solar energy in the presence of photosynthetic pigments are called photoautotrophs. For e.g., Nostoc, Char a, Porphyra and Wolffia. Nostoc is a cyanobacterium which contains photosynthetic pigments chlorophyll a, carotenoids and phycobilins. Chara is a green alga having chlorophyll a, b, carotenes and xanthophylls. Porphyra is a red alga containing chlorophyll a, carotenoids and phycobilins and Wolffia is an aquatic angiosperm which consists of photosynthetic pigments, chlorophyll a, b, carotenoids and xanthophylls.