Question

What are photoautotrophs?

Answer 1

Hint: They use the energy from sunlight to perform various cellular metabolic processes and do not depend upon other organisms for their nutritional requirements.

Complete answer:
1. Photoautotrophs are those organisms that absorb light energy to produce complex organic compounds like carbohydrates and acquire energy. They are mostly autotrophic and can fix carbon. The photoautotrophs can synthesize their food from inorganic substances in the presence of light as an energy source.
2. Photoautotrophs include green plants and photosynthetic bacteria, these organisms also called holophytic. These organisms produce energy from the light and synthesize their food and use carbon dioxide as their source of carbon.
3. The photoautotrophs are also known as photosynthetic organisms which are of two types:
Oxygenic photosynthetic organisms – they use chlorophyll to capture light energy and to oxidize water and break it into molecular oxygen.
4. Anoxygenic photosynthetic organisms – they have a substance called bacteriophyll which captures light energy by absorbing at non-optical wavelengths. They are aquatic organisms and oxidize hydrogen sulfide instead of water using light energy.
5. They are also the source of food for some heterotrophic organisms.
6. It is derived from the Greek word photo meaning “light “ and troph meaning “nourishment’.
7. They help in the process of biosynthesis and respiration and ate the producers in the food chain.

Note: The opposite of photoautotrophs are the photoheterotrophs that are organisms that depend on light for the source of energy and organic compounds for their carbon. They produce ATP through the process of photophosphorylation. They obtain their food requirements from the photoautotrophs.