[Campbell Biology P.245] Which statement accurately compares Photosystem I PS I and Photosys... | Practice Question

Which statement accurately compares Photosystem I PS I and Photosystem II PS II ?

  • A: PS II was named after PS I based on discovery order, but functions first in the light reactions.
  • B: The reaction-center chlorophyll a in PS I is called P680, and in PS II it is P700.
  • C: P680 and P700 are distinct types of chlorophyll molecules, differing significantly in their chemical structure.
  • D: Both PS I and PS II primarily absorb light in the blue spectrum.

Explanation

The text states that Photosystem II PS II and Photosystem I PS I were named in order of their discovery, but Photosystem II functions first in the light reactions. P680 and P700 are specific reaction-center chlorophyll a molecules found in PS II and PS I, respectively, absorbing red and far-red light, not blue light, and they are nearly identical chemically, with differences in absorption due to protein association.