Which of the following statements about cyanobacteria is/are true?

• A. Some are single cells, whereas others live in filamentous colonies.
• B. They are the only prokaryotes that perform plantlike, oxygenic photosynthesis.
• C. Some species may carry on nitrogen fixation.
• D. It can be said that nitrogen-fixing cyanobacteria are the most self-sufficient of all organisms.
• E. All of the listed responses are correct.

Answer: (E)

Verified step by step guidance

1. Understand the characteristics of cyanobacteria: Cyanobacteria are a group of photosynthetic bacteria, often referred to as blue-green algae. They are known for their ability to perform photosynthesis similar to plants, producing oxygen as a byproduct.
2. Examine the statement about cellular structure: Cyanobacteria can exist as single cells or form filamentous colonies. This diversity in structure allows them to adapt to various environments.
3. Evaluate the photosynthesis capability: Cyanobacteria are unique among prokaryotes because they perform oxygenic photosynthesis, similar to plants, using water as an electron donor and releasing oxygen.
4. Consider nitrogen fixation: Some cyanobacteria have specialized cells called heterocysts that allow them to fix atmospheric nitrogen into a form usable by living organisms, making them important contributors to nitrogen cycling in ecosystems.
5. Assess self-sufficiency: Nitrogen-fixing cyanobacteria are considered highly self-sufficient because they can produce their own food through photosynthesis and fix nitrogen, reducing their dependence on external sources for these essential processes.