Question

A bacterium that you isolated from pond water appears to use light for energy. Based upon this information, you inoculate the organism into fresh media, infused with lots of carbon dioxide. Even after incubation at the correct temperature (of pond water), the organism is not growing. Your best explanation of what might have happened is _________.

Answer 1

The question is incomplete as it does not have the options which are:

• there was no sulfur compound added to the medium, that could be used as an electron donor.
• no oxygen was added to the medium so the organism died.
• there is some inhibitory chemical that is preventing the growth of the bacterium.
• you were using the wrong type of sunlight as the energy source for the bacterium.

Answer:

There was no sulfur compound added to the medium, that could be used as an electron donor.

Explanation:

In the given question, the bacteria which are found in the pond uses light energy to use carbon dioxide and form the glucose molecule. These bacteria are known as phototrophic bacteria.

The process of photosynthesis requires an electron donor and an electron acceptor to use molecule.

The organism when provided the light and carbon dioxide artificially in a culture, the bacteria were not able to grow. The reason for this could be accounted as that there was no electron donor found in the media like sulfur which could donate the electron during the chain reaction.

Thus, the selected option is correct.