[Campbell Biology P.243] According to Figure 10.10, what is the primary structural differenc... | Practice Question

According to Figure 10.10, what is the primary structural difference between chlorophyll a and chlorophyll b, and how does this difference affect their properties?

  • A: Chlorophyll a has a methyl (CH3) group where chlorophyll b has a formyl (CHO) group, leading to slightly different absorption spectra and appearances under visible light.
  • B: Chlorophyll a has a longer hydrocarbon tail than chlorophyll b, which affects its embedding in the thylakoid membrane.
  • C: Chlorophyll a contains magnesium at its center, while chlorophyll b contains iron, which changes their light absorption properties.
  • D: Chlorophyll a has a porphyrin ring with four nitrogen atoms, while chlorophyll b has a simpler structure without these nitrogen atoms.

Explanation

Figure 10.10 clearly indicates that 'Chlorophyll a and b differ in only one functional group: CH3 in chlorophyll a, CHO in chlorophyll b.' The text further states: 'A slight structural difference between them is enough to cause the two pigments to absorb at slightly different wavelengths in the red and blue parts of the spectrum see Figure 10.9a .' This difference also leads to their distinct appearances chlorophyll a appears blue-green, chlorophyll b olive green .