9. Halobacterium has a photosynthetic membrane that is colored purple. Its photosynthetic action spectrum is exactly complementary the action spectrum for green plants. What wavelengths of light do the Halobacterium photosynthetic pigments absorb

Yellow-green

Explanation:

Let us remember that the colour that is transmitted is always complementary to the colour that is absorbed.

Hence, if a substance absorbs a particular colour, it will transit the colour complementary to that absorbed colour.

The complementary colour of yellow-green is purple hence yellow green light of wavelength 560 - 580 nm is absorbed.

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