Biology · Photosynthesis in Higher Plants · NEET
| Type of pigment | Chief (primary) pigment | Accessory pigment |
| Colour on chromatogram | Bright or blue-green | Yellow-green |
| Location / function | Present at reaction centre; traps light and starts electron flow | In antenna; absorbs light and transfers energy to chlorophyll a |
| Photosynthesis alone? | Yes, essential; reaction cannot occur without it | No; cannot run photosynthesis without chlorophyll a |
| Amount in leaf | More abundant | Less abundant |
Chlorophyll b is an accessory pigment. NCERT clearly lists chlorophyll b, xanthophylls and carotenoids as accessory pigments, while chlorophyll a is the chief pigment. Accessory pigments absorb light and hand the energy over to chlorophyll a; they do not carry out the reaction themselves.
Chlorophyll a is the pigment present at the reaction centre and is the one that actually traps light and starts the electron flow. All accessory pigments, including chlorophyll b, only funnel the energy they absorb into chlorophyll a. So chlorophyll a is the site where light energy is finally used, making it the chief pigment.
On a paper chromatogram of leaf pigments, chlorophyll a is bright or blue-green and chlorophyll b is yellow-green. Remember the full NCERT order of the four bands: chlorophyll a (blue-green), chlorophyll b (yellow-green), xanthophylls (yellow), carotenoids (yellow to yellow-orange). This exact colour match is a repeated NEET question.
No. If a plant had only chlorophyll b and lacked chlorophyll a, it could not carry out photosynthesis, because the reaction centre needs chlorophyll a to pass on the trapped energy. Chlorophyll b can absorb light but has no way to use it without chlorophyll a. This is a direct NCERT thought-question.
Accessory pigments like chlorophyll b widen the range of wavelengths that can be used for photosynthesis and also protect chlorophyll a from damage. Chlorophyll a alone absorbs mainly blue and red light; chlorophyll b captures some of the in-between wavelengths and transfers that energy to chlorophyll a, so together they use more of the visible spectrum.
Match List I (Pigment) with List II (Colour) and choose the correct answer: A. Chlorophyll a B. Chlorophyll b C. Xanthophylls D. Carotenoids || I. Yellow-green II. Yellow III. Blue-green IV. Yellow to Yellow-orange
Match List I with List II and choose the correct answer: A. Chlorophyll a B. Chlorophyll b C. Xanthophyll D. Carotenoid || I. Yellow to yellow orange II. Yellow green III. Blue green IV. Yellow
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Chlorophyll a is the more abundant and more important pigment in most leaves. Chlorophyll b is present in a smaller amount and works as a helper (accessory) pigment.
Chlorophyll a is the pigment at the reaction centre. The reaction-centre chlorophyll a of PS I absorbs at 700 nm (P700) and of PS II at 680 nm (P680).
Yes, both are shades of green, but they separate on a chromatogram: chlorophyll a is blue-green and chlorophyll b is yellow-green. This colour difference is what NEET tests.
Chlorophyll b is an accessory pigment. It absorbs light at wavelengths chlorophyll a misses and transfers that energy to chlorophyll a, widening the usable light range and protecting chlorophyll a.
NEET repeatedly asks match-the-column questions on pigment colours and on which pigment is the chief versus accessory. Knowing chlorophyll a (blue-green, chief) vs chlorophyll b (yellow-green, accessory) directly earns marks.
