Final answer:
An indicator that newly discovered bacteria are photosynthetic is their color, which is due to pigments like chlorophyll and bacteriochlorophylls that absorb light for photosynthesis. option a is correct.
Step-by-step explanation:
If a scientist discovers a new type of bacteria, the indicator that the newly discovered bacteria are most likely photosynthetic is their color.
This is because photosynthetic bacteria contain pigments, such as chlorophyll or bacteriochlorophylls, which are necessary to absorb light for the photosynthesis process. For instance, oxygenic cyanobacteria have pigments that give them a blue-green color.
Moreover, some photosynthetic bacteria, especially the phototrophic ones like the purple green bacteria, can have various colors such as green, purple, or blue because of the presence of bacteriochlorophylls and accessory pigments like carotenoids. These various pigments allow them to absorb different wavelengths of light, which is a fundamental aspect of photosynthesis.
Therefore, the presence of color, particularly blue-green, orange, red, or purple, can serve as an indicator of photosynthetic activity in the discovered bacteria.