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Which combination of the following statements is CORRECT for cyanobacteria ?
P. They can perform oxygenic photosynthesis
Q. Usually filamentous forms are involved in nitrogen fixation
R. Nitrogen fixation occurs in heterocysts
S. They cannot grow in a mineral medium exposed to light and air
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- P, Q and R
- P, S and R
- Q, R and S
- P, Q and S
Correct Option: A
Cyanobacteria are photosynthetic, and so can manufacture their own food. Cyanobacteria get their name from the bluish pigment phycocyanin, which they use to capture light for photosynthesis. They also contain chlorophyll a, the same photosynthetic pigment that plants use. Nitrification cannot occur in the presence of oxygen, so nitrogen is fixed in specialized cells called heterocysts. These cells have an especially thickened wall that contains an anaerobic environment. e.g.,: Filamentous form of Nostoc.
