Purple photosynthetic bacteria do not contain chloroplasts. They have an antenna system that includes two light- harvesting protein complexes, both of which are integral membrane proteins. The bacteriochlorophyll a molecules contain Mg²⁺and absorb light at 800 nm. Which of the following statements comparing photosynthesis in purple bacteria and plant chloroplasts is true?

Question

Quizplus · Accepted Answer

Purple bacteria have bacteriochlorophyll a that absorbs light at 800 nm, which is longer than the absorption wavelength of chlorophyll a in plant chloroplasts. Chlorophyll a in chloroplasts absorbs light at 680 nm, which is in the visible light range. Choice A is incorrect because purple bacteria do have electron transport associated with photosynthesis, even though they lack chloroplasts. Choice C is incorrect because bacteriochlorophyll a absorbs light efficiently at a longer wavelength than chlorophyll a in chloroplasts, not at a shorter wavelength in the ultraviolet range. Choice D is incorrect because bacteriochlorophyll a contains Mg in place of Fe in chlorophyll a, and the rest of the chemical structures are different as well.

Purple Photosynthetic Bacteria Do Not Contain Chloroplasts