All Free Biology MCQs with Answers

4041. An instrument used to measure relative abilities of different pigments to absorb different wavelengths of light is called:

• A. Photometer
• B. Light meter
• C. Spectrometer
• D. Spectrophotometer

Explanation: A spectrophotometer is used to measure relative abilities of different pigments to absorb different wavelengths of light.

4042. Porphyrin ring represents the:

• A. Hydrophobic head of chlorophyll
• B. Hydrophilic tail of chlorophyll
• C. Hydrophobic tail of chlorophyll
• D. Hydrophilic head of chlorophyll

Explanation: The head of chlorophyll is hydrophilic but tail of chlorophyll is hydrophobic. Head consists of four pyrrole rings.

4043. Chlorophyll head is made up of:

• A. Four joined porphyrin rings
• B. Four Joined tetrapyrrole rings
• C. Four joined pyrrole rings
• D. Two joined pyrrole rings

Explanation: It is tetrapyrrole means four pyrrole rings, however collectively four pyrrole rings constitute a porphyrin.

4044. In chlorophyll head, an atom of magnesium is coordinated with the:

• A. Carbon of each pyrrole ring
• B. Hydrogen of each pyrrole ring
• C. Nitrogen of each pyrrole ring
• D. Methyl of each pyrrole ring

Explanation: An atom of magnesium is present in the centre of porphyrin ring and is coordinated with the nitrogen of each pyrrole ring.

4045. _ of haemoglobin is also a porphyrin ring.

• A. α - chain
• B. β - chain
• C. Haem group
• D. Protein

Explanation: This is homology between hemoglobin and chlorophyll.

4046. Haem group of hemoglobin differs from porphyrin of chlorophyll in having:

• A. Iron as central atom
• B. Magnesium as central atom
• C. Four pyrrole rings
• D. Central atom coordinated with nitrogen of each pyrrole ring

Explanation: Haem have iron as central atom whereas porphyrin of chlorophyll have magnesium as central atom.

4047. Long tail of chlorophyll which is attached to one of the pyrrole is:

• A. Hydrocarbon tail
• B. Phytol
• C. Phytol or hydrocarbon tail
• D. Hydrophilic tail

Explanation: It is a hydrocarbon tail also called phytol.

4048. Chlorophyll a and Chlorophyll b differ from each other in only one of the:

• A. Atoms
• B. Elements
• C. Functional groups
• D. Carbon atoms

Explanation: It is methyl (CH3) for chl. a and carbonyl (CHO) for Chl. b.

4049. As compared to chlorophyll a, chlorophyll b have:

• A. Two more hydrogen atoms
• B. One less oxygen atom
• C. Two less hydrogen atoms and one more oxygen atom
• D. Two more hydrogen atom and one less oxygen atom

Explanation: Chlorophyll a and chlorophyll b differ from each other in only one of the functional groups bonded to the porphyrin; the methyl group (-CH3) in chlorophyll a is replaced by a terminal carbonyl group (-CHO) in chlorophyll b.

4050. As compared to chlorophyll b, chlorophyll a have:

• A. Two more hydrogen atoms
• B. One less oxygen atom
• C. Two less hydrogen atoms
• D. Two more hydrogen atom and one less oxygen atom

Explanation: Chlorophyll a have methyl group (-CH3) whereas chlorophyll b have carbonyl group (-CHO). Thus, chlorophyll a have two more hydrogen atoms and one less oxygen atom.