Question

Identify which of the following are characteristics of cyanobacteria.

Answer 1

Answer:

1. Gram-negative
2. Oxygenic phototrophs
3. **Anoxygenic phototrophs (only a few species)
4. May possess nitrogenase
5. Some species may form filamentous multicellular associations

Explanation:

Cyanobacteria, also known as blue-green algae, are organisms that obtain their energy through photosynthesis.

1. Cyanobacteria are considered gram-negative. However, studies show that their envelope exhibit some gram-positive characteristics.

2. Cyanobacteria and other organisms, such as algae, use photosynthesis take the energy from light (the sun), which results in the generation of oxygen as a byproduct. Therefore, they are oxygenic phototrophs.

3. Anoxygenic organisms don't generate oxygen as a byproduct and use hydrogen sulfide rather than water. Although most cyanobacteria are oxygenic phototrophs, few species, such as Oscillatoria limnetica, have developed environmental adaptations such as the ability of sulphide-dependent anoxygenic photosynthesis (Hamilton, 2019).

4. and 5. Some species of cyanobacteria form filamentous multicellular associations (some are unicellular species) and synthesize the enzyme nitrogenase to fix molecular nitrogen.