All of the following are correct differences between Chl. 'a' and 'b' except:
Correct answer: C. Chlorophyll 'a' is found only in plants, while chlorophyll 'b' is found only in algae
- A. Chlorophyll 'a' has a methyl (-CH₃) group at the C-3 position, while chlorophyll 'b' has a formyl (-CHO) group at the same position
- B. Chlorophyll 'a' absorbs light primarily at 430 nm and 662 nm, whereas chlorophyll 'b' absorbs at 453 nm and 642 nm
- C. Chlorophyll 'a' is found only in plants, while chlorophyll 'b' is found only in algae
- D. Chlorophyll 'a' participates directly in the light reactions of photosynthesis, whereas Chlorophyll 'b' acts as an accessory pigment
Explanation
Chlorophyll 'a' and 'b' differ in their chemical structure, absorption spectra, and roles in photosynthesis. Structurally, chlorophyll 'a' has a methyl group (-CH₃) at the C-3 position of the porphyrin ring, whereas chlorophyll 'b' has a formyl group (-CHO), which slightly shifts its light absorption properties. In terms of absorption, chlorophyll 'a' absorbs light mainly at 430 nm (blue-violet) and 662 nm (red), while chlorophyll 'b' absorbs at 453 nm (blue) and 642 nm (red), complementing chlorophyll 'a' in capturing light energy. Functionally, chlorophyll 'a' is directly involved in the photochemical reactions of the light-dependent reactions of photosynthesis, whereas chlorophyll 'b' acts as an accessory pigment, transferring the absorbed energy to chlorophyll 'a'. However, it is incorrect to say that chlorophyll 'a' is found only in plants and chlorophyll 'b' only in algae, because both types are present in plants and green algae, making that statement the exception among the differences.
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