Question

What did Engelmann observe from his prism experiments?
A. Bacteria could not be used to detect the sites of O, evolution
B. Bacteria accumulated and released excess carbon dioxide in red and blue light
C. Bacteria accumulated due to increases in temperature caused by increase in oxygen concentration
D. Bacteria are accumulated towards red and blue light

Answer 1

Engelmann is the German botanist, where he has done experiments to measure the effect of different colors of light on photosynthesis, and he also showed how the light energy converts to chemical energy in the chloroplast.

Complete answer:
For this experiment, Engelmann used the modified microscope, which is equipped with the prism, so that the spectrum of the visible light will fall on the microscopic slide.
He used the photosynthetic algae for the experiment, where he exposes the algae to the visible spectrum, and he used different algae for the different colors of light.
He added the aerobic bacteria to the setup and exposed it to a different wavelength of light and he counted the bacteria where it is accumulated so that it helps to identify which light is more suitable for photosynthesis.
And he observed that oxygen-dependent bacteria was accumulated on the algae more the areas of the red and blue light, which indicates that these wavelengths of light are most suitable for photosynthesis

So from the above explanation of the experiment and from the given options, the correct option is D because in this experiment he observed bacteria accumulating more towards red and blue light.

Note:
The reason why more aerobic bacteria accumulated in that region is, in the presence of red and blue light more photosynthesis occurs and more oxygen release, this allows the bacteria to proliferate more, as the bacteria used here are aerobic bacteria.