IGCSE Biology Paper-1: Specimen Questions with Answers 129 - 129 of 208

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Question 129

MCQ▾

Which element is found in a molecule of Chlorophyll?

Chlorophyll is the main pigment, useful in photosynthesis.
Chlorophyll shows porphyrin structure.
It is a large molecule composed of four 5-membered rings called pyrrole rings and a central core of magnesium. A side chain, called the phytol chain extends from one of the pyrrole rings.
Phytol chain is composed of insoluble carbon and hydrogen atoms and helps to anchor chlorophyll molecules with the thylakoids.
Chlorophyll is a green pigment because it does not absorb green light, but reflects green light, so gives green colour to the leaves.
In plants, two kinds of chlorophyll (chlorophyll - a and chlorophyll - b) are present.
Chlorophyll - a is two or three times more in quantity than chlorophyll - b and acts as the reaction center.
On absorbing light, the chlorophyll - b molecule is excited and transfers its energy to chlorophyll - a which converts the light energy into electrical energy. Thus, act as reaction center. Chlorophyll - a is a bluish-green while chlorophyll - b is olive-green. Both are soluble in organic solvents like alcohol, acetone etc. Chlorophyll – a (C₅₅H₇₂O₅N₄Mg) possesses – CH₃ (methyl group) , which is replaced by – CHO (an aldehyde) group in chlorophyll – b (C₅₅H₇₀O₆N₄Mg) .