This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Pigments Involved in Photosynthesis”.
1. Which of the following is not an accessory pigment?
a) Chlorophyll a
c) Chlorophyll b
Explanation: Chlorophyll is not an accessory pigment as it the chief pigment of the chloroplast. Chlorophyll b, xanthophyll, and carotenoids are accessory pigments. Bacteriochlorophyll and phycobilin are other pigments present in leaves.
2. Which is the correct color matching in chromatogram?
a) Chlorophyll a – yellow-green
b) Chlorophyll b – yellow-orange
c) Xanthophyll – yellow
d) Carotenoids – bright or blue-green
Explanation: Xanthophyll shows a yellow color. Chlorophyll a shows bright or blue – green color whereas chlorophyll b shows yellow – green. Carotenoids show varying color from yellow to yellow – orange.
3. Which of the following is the main function of carotenes?
a) Not an accessory pigment
c) Helps in photosynthesis
d) Helps in transpiration
Explanation: They just have mainly two functions. That is photooxidation which means they produce oxygen due to light. Also, it helps the plant from photodamage i.e. the plant gets protected from excess heat. Carotene is also known as an accessory pigment.
4. Methyl group is mainly present in which photosynthetic pigment?
a) Chlorophyll b
d) Chlorophyll a
Explanation: Methyl group CH3 is mainly present in chlorophyll a. But in chlorophyll b, it has an aldehyde group in the C7 position. Chlorophyll a and b structure mainly differs in the substituent of porphyrin.
5. Chlorophyll is soluble in water.
Explanation: It is a wrong statement. Chlorophyll is not soluble in water since it has a hydrophobic tail. It is soluble only in solvents like alcohol, acetone, etc. which has the capability to extract chlorophyll.
6. Who found out that the pigment chlorophyll is found in the chloroplast in plant cells?
a) Robert Hill
b) Hugo de Vries
c) Julius Von Sachs
d) C. Van Neil
Explanation: Julius Von Sachs found out that the pigment chlorophyll is present in chloroplast. Von Sachs in his experiment found out glucose stored in the form of starch. This led to the discovery of pigment chlorophyll in the chloroplast.
7. What is the empirical formula of chlorophyll b?
Explanation: The empirical formula of chlorophyll b is C55H70O6N4Mg. They have 55 atoms of carbon, 70 atoms of hydrogen, 6 atoms of oxygen, 4 atoms of nitrogen and one atom magnesium. They are very microscopic and officially an accessory pigment.
8. How many numbers of chlorophyll are present in a photosynthetic unit?
a) 100 – 150
c) 200 – 250
d) 300 – 350
Explanation: In a photosynthetic unit, 200 – 250 number of chlorophylls are present. They are embedded in the thylakoids of chloroplast. It differs for different plant species as in algae, it is only 100 in number. The number of chlorophylls is based on their requirement and function.
9. The size of the chlorophyll molecule is Head: 20 x 20 A°, Tail: 15 A°
Explanation: It is a wrong statement. They have a perfect body structure with a head and tail. The size of the chlorophyll molecule is Head: 15 x 15 A°, Tail: 20 A°. The size of the head is slightly smaller than the tail by 5 A°. They can be measured only in Angstrom unit because of their minute size.
10. Which is false regarding chlorophyll a and b?
a) Chlorophyll b is an accessory pigment
b) Chlorophyll is the main chief pigment
c) Chlorophyll a is more than chlorophyll b
d) Both are present in equal proportion
Explanation: In chloroplast, chlorophyll-a is more than chlorophyll b. They are not present in equal proportion. Since chlorophyll-a is the main chief pigment in photosynthesis, it is more in number. Chlorophyll b is less in number since it is only an accessory pigment.
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