Question

Which is correct about chlorophyll, a and b in leaves of higher plants?
A. Both are present in equal proportion
B. Chlorophyll a is more than chlorophyll b
C. Chlorophyll a is less than chlorophyll b
D. Chlorophyll b is ten times more than chlorophyll a

Answer 1

Hint: Chlorophyll a and b are the forms of chlorophyll. Chlorophyll a is used in oxygenic photosynthesis and helps in absorbing most energy from the wavelengths of violet-blue and orange-red light. Chlorophyll b helps in photosynthesis by absorbing light energy.

Complete answer:
Chlorophyll a is a bluish or bright green pigment and it is a universal photosynthetic pigment. It is also known as primary photosynthetic pigment and is the most abundant photosynthetic pigment. The molecular structure of chlorophyll consists of a chlorine ring, four nitrogen atoms surround a central magnesium atom, and have attached side chains and a hydrocarbon tail.
Chlorophyll b is a yellow-green pigment and it is structurally similar to chlorophyll a, except it has CHO group in the place of methyl group. Chlorophyll b is more soluble than chlorophyll a in polar solvents because of its carbonyl group. In shade plants, the light harvested antennae around the photosystem II contain the majority of chlorophyll b. But quantity of chlorophyll b is half of chlorophyll a in light exposed higher plants.

Hence, the correct option is B. Chlorophyll a is more than chlorophyll b.

Note: In shade adapted chloroplasts, which have increased ratio of photosystem II to photosystem I, there is a high ratio of chlorophyll b as compared to chlorophyll a. Increase in chlorophyll b increases the range of wavelengths absorbed by the shade chloroplasts.