Question 1

   Question: Match List-I with List-II. Choose the option with all correct matches.

   Options: 

       A. A-I, B-II, C-IV, D-III

       B. A-I, B-IV, C-III, D-II

       C. A-III, B-IV, C-II, D-I

       D. A-III, B-I, C-II, D-IV

   Correct Answer: D

   Year: NEET 2025

   Solution: A chromatographic separation of the leaf pigments shows that the colour that we see in leaves is not due to a single pigment but due to four pigments.

   Step Solution:

    1.  Observe the provided list of pigments and their respective colors in a chromatogram.

    2.  Recall that Chlorophyll a typically presents as bright or blue-green.

    3.  Identify that Chlorophyll b appears yellow-green.

    4.  Match Xanthophylls with yellow and Carotenoids with yellow to yellow-orange.

    5.  Select the option that aligns these pairings (A-III, B-I, C-II, D-IV).

   Difficulty Level: Easy

   Concept Name: Paper Chromatography of Leaf Pigments

   Shortcut Solution: Remember "A is for Azure (Blue-green)" and "B is for Bright-yellowish-green" to quickly distinguish the two chlorophylls.

Question 10

   Question: The reaction centre in PS II has an absorption maxima at

   Options: 

       A. 700 nm

       B. 660 nm

       C. 780 nm

       D. 680 nm

   Correct Answer: D

   Year: NEET 2023

   Solution: In PS-I, the reaction centre chlorophyll a has an absorption peak at 700 nm, while in PS-II, the reaction centre has an absorption maxima at 680 nm.

   Step Solution:

    1.  Identify the two primary photosystems involved in light reactions: PS I and PS II.

    2.  Recall the naming convention based on the discovery order, which also corresponds to their absorption peaks.

    3.  Assign P700 to PS I.

    4.  Assign P680 to PS II.

   Difficulty Level: Easy

   Concept Name: Reaction Centers (P680 and P700)

   Shortcut Solution: PS II has the lower wavelength (680) compared to PS I (700).

Question 12

   Question: Choose the correct answer from the options given below: (Matching pigments to colors)

   Options: 

       A. (A)-(III), (B)-(II), (C)-(IV), (D)-(I)

       B. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)

       C. (A)-(II), (B)-(III), (C)-(I), (D)-(IV)

       D. (A)-(IV), (B)-(III), (C)-(II), (D)-(I)

   Correct Answer: A

   Year: NEET 2023 mpr

   Solution: Chlorophyll a appears bright or blue green; Chlorophyll b appears yellow green; Xanthophyll appears yellow; Carotenoid appears yellow to yellow-orange.

   Step Solution:

    1.  Match (A) Chlorophyll a with (III) Blue green.

    2.  Match (B) Chlorophyll b with (II) Yellow green.

    3.  Match (C) Xanthophyll with (IV) Yellow.

    4.  Match (D) Carotenoid with (I) Yellow to yellow orange.

   Difficulty Level: Medium

   Concept Name: Chromatographic Separation

   Shortcut Solution: Focus on Xanthophyll = Pure Yellow to eliminate other options quickly.

Question 34

   Question: Water soluble pigments found in plant cell vacuoles are

   Options: 

       A. carotenoids

       B. anthocyanins

       C. xanthophylls

       D. chlorophylls.

   Correct Answer: B

   Year: NEET I 2016

   Solution: Anthocyanins are water soluble pigments, which commonly occur in membrane enclosed vacuoles. They are responsible for the colour of fruits and flower petals.

   Step Solution:

    1.  Classify pigments by solubility: Chlorophylls and Carotenoids are fat-soluble (located in thylakoids).

    2.  Identify water-soluble pigments found in plants.

    3.  Select anthocyanins as they are stored in the aqueous environment of the vacuole.

   Difficulty Level: Medium

   Concept Name: Pigment Solubility and Location

   Shortcut Solution: Only anthocyanins are non-photosynthetic and water-soluble among these choices.

Question 36

   Question: Chromatophores take part in

   Options: 

       A. movement

       B. respiration

       C. photosynthesis

       D. growth

   Correct Answer: C

   Year: 2015

   Solution: Chromatophores are the internal membrane systems of photosynthetic forms which possess photosynthetic pigments. They occur in photoautotrophic bacteria.

   Step Solution:

    1.  Define chromatophores as specialized membrane structures in prokaryotes.

    2.  Identify their contents: photosynthetic pigments.

    3.  Conclude their function is photosynthesis.

   Difficulty Level: Easy

   Concept Name: Bacterial Photosynthetic Structures

   Shortcut Solution: "Chroma" (color) + "phore" (bearer) in bacteria = photosynthetic pigment holders.

Question 62

   Question: Which fractions of the visible spectrum of solar radiations are primarily absorbed by carotenoids of the higher plants?

   Options: 

       A. Blue and green

       B. Green and red

       C. Red and violet

       D. Violet and blue

   Correct Answer: D

   Year: 2003

   Solution: Carotenoids of higher plants are fat soluble compounds that include carotenes and xanthophylls. Most of them absorb light of violet and blue range.

   Step Solution:

    1.  Recall the absorption spectrum of accessory pigments.

    2.  Identify that carotenoids reflect yellow/orange, meaning they absorb the opposite end of the spectrum.

    3.  Select the violet and blue range.

   Difficulty Level: Medium

   Concept Name: Absorption Spectrum

   Shortcut Solution: Carotenoids absorb the highest energy (shortest wavelength) visible light: Violet/Blue.

Question 66

   Question: Which element is located at the centre of the porphyrin ring in chlorophyll?

   Options: 

       A. Calcium

       B. Magnesium

       C. Potassium

       D. Manganese

   Correct Answer: B

   Year: 2003

   Solution: Chlorophyll consists of a porphyrin head and a phytol tail. Porphyrin is a cyclic tetrapyrrole structure, having a magnesium atom in the centre.

   Step Solution:

    1.  Recall the empirical formula of Chlorophyll-a: $C_{55}H_{72}O_5N_4Mg$.

    2.  Identify the central metal ion coordinating with the four pyrrole rings.

    3.  Confirm it is Magnesium.

   Difficulty Level: Easy

   Concept Name: Molecular Structure of Chlorophyll

   Shortcut Solution: Mg is the "heart" of Chlorophyll (similar to Fe in Hemoglobin).

Question 70

   Question: Which pigment absorbs the red and far-red light?

   Options: 

       A. Cytochrome

       B. Phytochrome

       C. Carotenoids

       D. Chlorophyll

   Correct Answer: B

   Year: 2002

   Solution: Phytochrome occurs in 2 forms, i.e. $P_R$ and $P_{FR}$ (red light and far red light absorbing forms) and these 2 forms are interconvertible.

   Step Solution:

    1.  Differentiate between photosynthetic pigments and signaling pigments.

    2.  Identify Phytochrome as the sensory pigment for light quality.

    3.  Note its two interconvertible forms: Red-absorbing ($P_R$) and Far-Red absorbing ($P_{FR}$).

   Difficulty Level: Medium

   Concept Name: Phytochromes

   Shortcut Solution: "Phyto" + "chrome" = light detector; "R" and "FR" specifically refer to Red and Far-Red.

Question 80

   Question: Chlorophyll a molecule at its carbon atom 3 of the pyrrole ring II has one of the following

   Options: 

       A. carboxylic group

       B. magnesium

       C. aldehyde group

       D. methyl group

   Correct Answer: D

   Year: 1997

   Solution: In chlorophyll a, a methyl group ($CH_3$) is attached to the third carbon in the porphyrin head.

   Step Solution:

    1.  Recall the structural difference between Chlorophyll a and b.

    2.  Identify the specific substituent on the second pyrrole ring.

    3.  Note that Chl a has a methyl group, while Chl b has an aldehyde group.

   Difficulty Level: Hard

   Concept Name: Fine Structure of Chlorophyll

   Shortcut Solution: A is for Methyl ($CH_3$), B is for Al-B-hyde ($CHO$).

Question 81

   Question: The core metal of chlorophyll is

   Options: 

       A. Ni

       B. Cu

       C. Fe

       D. Mg

   Correct Answer: D

   Year: 1997

   Solution: Porphyrin is a cyclic tetrapyrol structure, having a magnesium atom in the centre.

   Step Solution:

    1.  Analyze the chemical composition of the porphyrin head.

    2.  Identify the divalent cation at the center.

    3.  Select Magnesium.

   Difficulty Level: Easy

   Concept Name: Chemical Composition of Chlorophyll

   Shortcut Solution: Chlorosis (yellowing) due to Magnesium deficiency occurs because it is the central atom of chlorophyll.

Question 90

   Question: Which of the following pigments acts as a reaction-centre during photosynthesis?

   Options: 

       A. Carotene

       B. Phytochrome

       C. $P_700$

       D. Cytochrome

   Correct Answer: C

   Year: 1994

   Solution: The majority of pigments serve as an antenna complex... transfusing energy to the reaction center complex... PSI absorbs red light of wavelengths greater than 700 nm.

   Step Solution:

    1.  Distinguish between antenna pigments (transfer energy) and reaction centers (convert energy).

    2.  Identify P700 and P680 as the only pigments that can actually eject electrons.

    3.  Choose P700 from the options.

   Difficulty Level: Easy

   Concept Name: Reaction Center

   Shortcut Solution: Any pigment named "P[number]" is a reaction center.

Question 96

   Question: Chlorophyll a occurs in

   Options: 

       A. all photosynthetic autotrophs

       B. in all higher plants

       C. all oxygen liberating autotrophs

       D. all plants except fungi.

   Correct Answer: C

   Year: 1992

   Solution: Chlorophyll-a occur in all photosynthesizing plants except bacteria. It is believed to be specifically required for oxygen-evolving organisms.

   Step Solution:

    1.  Consider different types of autotrophs (bacterial vs. plant).

    2.  Note that photosynthetic bacteria use bacteriochlorophyll, not Chl a.

    3.  Identify that all organisms that release oxygen (cyanobacteria, algae, plants) must have Chlorophyll a.

   Difficulty Level: Medium

   Concept Name: Distribution of Photosynthetic Pigments

   Shortcut Solution: Chl a = Essential for splitting water (Oxygen liberation).

Question 104

   Question: Photosynthetic pigments found in the chloroplasts occur in

   Options: 

       A. thylakoid membranes

       B. plastoglobules

       C. matrix

       D. chloroplast envelope.

   Correct Answer: A

   Year: 1991

   Solution: Photosynthetic pigments are found in the thylakoid membrane of chloroplasts. Chlorophylls and other photosynthetic pigments are confined to grana.

   Step Solution:

    1.  Recall the anatomy of a chloroplast: stroma vs. grana.

    2.  Identify the site of the light-dependent reactions.

    3.  Locate pigments within the lipid bilayer of the thylakoid membranes.

   Difficulty Level: Easy

   Concept Name: Chloroplast Ultrastructure

   Shortcut Solution: Light reactions = Thylakoids; Pigments = Light absorbers.

Question 109

   Question: The size of chlorophyll molecule is

   Options: 

       A. head $15 \times 15A,$ tail 25 A

       B. head $20 \times 20 A,$ tail 25 A

       C. head $15 \times 15 A$, tail 20 A

       D. head $10 \times 12 A$, tail 25 A

   Correct Answer: C

   Year: 1989

   Solution: Chlorophyll are the magnesium porphyrin (head, $15 \times 15 \text{ \AA}$) compounds. A long chain of C atoms called as phytol (tail; 20 \AA) is attached.

   Step Solution:

    1.  Identify the two parts of the molecule: porphyrin head and phytol tail.

    2.  Determine the dimensions of the square porphyrin ring ($15 \times 15 \text{ \AA}$).

    3.  Determine the length of the lipophilic phytol tail ($20 \text{ \AA}$).

   Difficulty Level: Hard

   Concept Name: Molecular Dimensions of Chlorophyll

   Shortcut Solution: Head is a square (15x15) and the tail is slightly longer (20).