Question

How are photoautotrophs different from photoheterotrophs?

Answer 1

Hint: Photoautotrophs are organisms, such as plants that can synthesize their own food from inorganic material in the presence of light whereas photoheterotrophs are those organisms that use light as a source of energy. They do not take up carbon directly from the air but take it up from the organic compounds present in the environment.

Complete answer:
Phototrophs are those organisms that use light as a source of energy to produce ATP to carry out various cellular processes. Not all phototrophs are photosynthetic but they are dependent on heterotrophs for food. All the phototrophs either use an electron transport chain or a proton pump to establish an electrochemical gradient utilized by the ATP synthesis to provide energy to the cell.

It is divided into two types on the basis of their metabolism:
1. PHOTOAUTOTROPHS- They are the organisms that carry out photosynthesis using sunlight, carbon dioxide and water are converted into organic materials to be used in cellular functions. In an ecological context, they provide nutrition for all other forms of life present on earth. Terrestrial environments include aquatics such as algae, protists, and bacteria. Photosynthetic bacteria and cyanobacteria build up carbon dioxide and water into organic cell materials using energy from sunlight. The starch is the final by-product of it.

2. Photoheterotrophs - They obtain their energy from sunlight and carbon from organic material present in the atmosphere. Photoheterotrophs produce ATP through photophosphorylation but use environmentally obtained organic compounds to build structures and other biomolecules. These organisms are also called holophytic. In short, we can say that these organisms are dependent on light for the source of energy and organic compounds for the extraction of carbon.

DIFFERENCE-

Photoautotrophs	Photoheterotrophs
They take up energy from the sun and utilize it for the production of food	They take up energy from the sun that they use to do metabolic activities.
Carbon dioxide is taken from the atmosphere.	Carbon dioxide is taken up from organic substances present in the environment.
They are the source of food for photoheterotrophs.	They take up food from the photo autotrophs.

Note: In ecological contexts, phototrophs are the main source of food for heterotrophic life. Phototrophs are organisms that utilize solar electromagnetic radiation for energy conservation.