This set of Class 11 Biology Chapter 9 Multiple Choice Questions & Answers (MCQs) focuses on “Biomolecules – Structure of Proteins-1”.
1. Proteins are heteropolymers of ______
a) lipids
b) monosaccharides
c) peptides
d) amino acids
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Explanation: Proteins are heteropolymers made of amino acid monomers. There are 21 amino acids. Various numbers and combinations of amino acids in a sequence or chain forms different types of proteins.
2. Structure of molecules in inorganic chemistry refers to the ______
a) three-dimensional structure
b) two-dimensional structure
c) molecular formula
d) primary structure
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Explanation: Structure of molecules in inorganic chemistry refers to the molecular formula of the compound. In organic chemistry it refers to the two-dimensional structure while in physics it refers to the three-dimensional structure.
3. Structure of molecules in physics refers to the ______
a) primary structure
b) two-dimensional structure
c) three-dimensional structure
d) molecular formula
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Explanation: In physics, the structure of molecules refers to the three-dimensional structure of the molecule. In inorganic chemistry it refers to the molecular formula of the compound. In organic chemistry it refers to the two-dimensional structure.
4. How many levels of organization do proteins have?
a) 4
b) 3
c) 2
d) 5
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Explanation: There are four levels of structural organization of proteins. These are the primary structure, secondary structure, tertiary structure and the quaternary structure. The level affects the function of the protein.
5. What is the configuration of proteins in the primary structure?
a) Helix
b) Line
c) Sheet
d) Globule
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Explanation: In the primary structure of proteins, the proteins are imagined to be arranged in a linear fashion such as a line. Helix and sheets are the configuration of proteins for the secondary structure.
6. What makes up the primary structure of proteins?
a) Peptides
b) Peptones
c) Amino acids
d) Polypeptides
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Explanation: The primary structure of amino acids is made of monomers of amino acids. The amino acids are linked together by peptide bonds between the amino group of one amino acid and the carboxyl group of the adjacent one.
7. What is the left end of the primary structure of proteins represented by?
a) First amino acid
b) Last amino acid
c) Cofactor
d) Methyl group
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Explanation: The primary structure of amino acids is made of monomers of amino acids. Hence, cofactors are absent. The left end of the primary or linear structure of proteins is represented by the first amino acid.
8. What is the right end of the primary structure of proteins represented by?
a) Methyl group
b) Cofactor
c) First amino acid
d) Last amino acid
View Answer
Explanation: The primary structure of amino acids is made of monomers of amino acids. Hence, cofactors are absent. The right end of the primary or linear structure of proteins is represented by the last amino acid.
9. What is the first amino acid of the primary structure known as?
a) A-terminal amino acid
b) C-terminal amino acid
c) N-terminal amino acid
d) L-terminal amino acid
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Explanation: The left end of the primary or linear structure of proteins is represented by the first amino acid. The left end of the first amino acid contains the amino group and is hence called the N-terminal.
10. A protein thread exists as an extended rigid rod. True or false?
a) True
b) False
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Explanation: It is false as a protein thread cannot exist as an extended rigid rod conformation. It undergoes folding in the form of helices or sheets with the help of various interactions. This represents the secondary structure.
11. What is the last amino acid of the primary structure known as?
a) N-terminal amino acid
b) L-terminal amino acid
c) S-terminal amino acid
d) C-terminal amino acid
View Answer
Explanation: The right end of the primary or linear structure of proteins is represented by the last amino acid. The right end of the first amino acid contains the carboxyl group and is hence called the C-terminal.
12. Identify the labeled portion of the peptide.
a) N-terminal amino acid
b) C-terminal amino acid
c) L-terminal amino acid
d) S-terminal amino acid
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Explanation: The diagram represents a primary structure or linear structure. The amino acid on the left represents the first amino acid. The left end of the first amino acid contains the amino group and is hence called the N-terminal.
13. Identify the labeled portion of the peptide.
a) I-terminal amino acid
b) N-terminal amino acid
c) C-terminal amino acid
d) L-terminal amino acid
View Answer
Explanation: The diagram represents a primary structure or linear structure. The amino acid on the right represents the last amino acid. The right end of the last amino acid contains the carboxyl group and is hence called the C-terminal.
14. Which of these bonds is present in the primary structure of protein?
a) Peptide bond
b) Glycosidic bond
c) Hydrogen bond
d) Disulfide bonds
View Answer
Explanation: The primary structure of amino acids is made of monomers of amino acids. The amino acids are linked together by peptide bonds between the amino group of one amino acid and the carboxyl group of the adjacent one.
15. Which of these is a type of secondary structure of proteins?
a) Line
b) Sheet
c) Globule
d) Spherical
View Answer
Explanation: The secondary structure of proteins is formed by the folding of the primary or linear structure. The linear chain of amino acids may be folded into a helix or a sheet. These are the secondary structures.
Sanfoundry Global Education & Learning Series – Biology – Class 11.
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