CUET UG Chemistry Booster Test - 2 Proteins and Amino Acids -

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CUET UG Chemistry Booster Test - 1 Proteins and Amino Acids

⏱️ 30 Minutes

❓ 20 Questions

📌 Answers are locked once submitted — results and explanations appear at the end.

CUET UG Chemistry Booster Test - 1 Proteins and Amino Acids

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QUESTION 1 OF 20

Chemically, all structural and functional proteins found in living systems are polymers of:

Answer Review

1 Chemically, all structural and functional proteins found in living systems are polymers of:

A Nucleotides

B α-amino acids

C Monosaccharides

D Fatty acids

💡 Short Explanation

�� Proteins are biological macromolecules. �� They are formed by linking amino acids. �� Naturally occurring proteins are polymers of α-amino acids.

✅ Correct Answer Explanation

Proteins are long-chain polymers formed by the linkage of α-amino acids through peptide bonds. These amino acids serve as the fundamental building blocks of all proteins found in living organisms.

❓ Why Other Options Are Incorrect

�� Option A → Nucleotides form nucleic acids.
�� Option C → Monosaccharides form carbohydrates.
�� Option D → Fatty acids are components of lipids.

🎯 Strategy

Used

Direct Recall

Application:

Identify the monomer unit of proteins.

Final Logic:

Proteins are polymers of α-amino acids.

🧠 Memory Trick

Protein = Polymer of Amino Acids

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Proteins and Amino Acids

2 Consider the following statements regarding proteins:
1. Proteins are the most abundant biomolecules of the living system.
2. They are polymers of β-amino acids.
3. Chief sources include milk, cheese, and pulses.
4. The word proteios means secondary.
Which combination of statements is correct?

A 1 and 3

B 1, 2 and 3

C 3 and 4

D 2 and 4

💡 Short Explanation

�� Proteins are highly abundant biomolecules. �� Milk, cheese, and pulses are important sources. �� Natural proteins are polymers of α-amino acids.

✅ Correct Answer Explanation

Statement 1 is correct because proteins are among the most abundant biomolecules in living organisms. Statement 2 is incorrect because proteins are polymers of α-amino acids, not β-amino acids. Statement 3 is correct because milk, cheese, and pulses are major dietary sources of proteins. Statement 4 is incorrect because proteios means "primary" or "of prime importance." Therefore, Statements 1 and 3 are correct.

❓ Why Other Options Are Incorrect

�� Option B → Includes incorrect Statement 2.
�� Option C → Includes incorrect Statement 4.
�� Option D → Both statements are incorrect.

🎯 Strategy

Used

Statement Verification

Application:

Evaluate each statement individually.

Final Logic:

Only Statements 1 and 3 are correct.

🧠 Memory Trick

Proteins = Primary, Not Secondary

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Introduction to Proteins

3 The trivial name "Tyrosine" was derived from a Greek word reflecting its initial discovery source. What does "tyros" mean?

A Sweet

B Milk

C Cheese

D Butter

💡 Short Explanation

�� Tyrosine was first isolated from cheese. �� The name comes from the Greek word "tyros." �� Tyros means cheese.

✅ Correct Answer Explanation

Tyrosine was first obtained from cheese, and its name originates from the Greek word "tyros," which means cheese.

❓ Why Other Options Are Incorrect

�� Option A → Incorrect meaning.
�� Option B → Refers to milk, not tyros.
�� Option D → Not related to the origin of the name.

🎯 Strategy

Used

Direct Recall

Application:

Recall the origin of the amino acid name.

Final Logic:

Tyros = Cheese.

🧠 Memory Trick

Tyrosine → Tyros → Cheese

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Amino Acids

4 Which of the following naturally occurring α-amino acids lacks an asymmetric carbon atom, making it optically inactive?

A Alanine

B Valine

C Leucine

D Glycine

💡 Short Explanation

�� Glycine contains two hydrogen atoms attached to the α-carbon. �� Therefore, the α-carbon is not chiral. �� Glycine is optically inactive.

✅ Correct Answer Explanation

In glycine, the α-carbon is attached to –H, –H, –NH₂, and –COOH. Since two substituents are identical, the carbon is not asymmetric and glycine is optically inactive.

❓ Why Other Options Are Incorrect

�� Option A → Contains a chiral α-carbon.
�� Option B → Optically active.
�� Option C → Optically active.

🎯 Strategy

Used

Structure Analysis

Application:

Identify the amino acid without a chiral center.

Final Logic:

Glycine lacks an asymmetric carbon.

🧠 Memory Trick

Glycine = Two H's = No Chirality

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Optical Activity of Amino Acids

5 Match the following amino acids with their physiological type.

List I	List II
1. Histidine	a. Non-essential amino acid
2. Glutamic acid	b. Essential amino acid
3. Arginine	c. Essential amino acid
4. Aspartic acid	d. Non-essential amino acid

A 1-a, 2-b, 3-c, 4-d

B 1-b, 2-a, 3-d, 4-c

C 1-a, 2-d, 3-b, 4-c

D 1-c, 2-a, 3-d, 4-b

💡 Short Explanation

�� Histidine and arginine are essential amino acids. �� Glutamic acid and aspartic acid are non-essential.

✅ Correct Answer Explanation

Matching: 1. Histidine → Essential 2. Glutamic acid → Non-essential 3. Arginine → Essential 4. Aspartic acid → Non-essential Thus: 1-b, 2-a, 3-b, 4-a

❓ Why Other Options Are Incorrect

�� Options B, C and D contain incorrect classifications.

🎯 Strategy

Used

Matching

Application:

Classify amino acids based on dietary requirement.

Final Logic:

Histidine and arginine are essential; glutamic and aspartic acids are non-essential.

🧠 Memory Trick

HA Essential, GA Non-Essential

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Essential and Non-Essential Amino Acids

6 Amino acids that must be obtained through diet because the human body lacks the metabolic pathways to synthesise them are called:

A Non-essential amino acids

B Essential amino acids

C Zwitter ions

D Denatured amino acids

💡 Short Explanation

�� The body cannot synthesise them sufficiently. �� They must be supplied through food. �� Therefore they are called essential amino acids.

✅ Correct Answer Explanation

Essential amino acids are those that cannot be synthesised by the human body in adequate amounts and therefore must be obtained from dietary sources.

❓ Why Other Options Are Incorrect

�� Option A → Can be synthesised by the body.
�� Option C → Ionic form of amino acids.
�� Option D → Refers to altered proteins.

🎯 Strategy

Used

Definition Recall

Application:

Identify amino acids that require dietary intake.

Final Logic:

Diet-required amino acids are essential.

🧠 Memory Trick

Essential = Eat Them

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Essential Amino Acids

7 Based on the relative number of functional groups, Aspartic acid and Glutamic acid naturally belong to which category?

A Acidic

B Basic

C Neutral

D Amphoteric

💡 Short Explanation

�� Both contain extra carboxyl groups. �� More carboxyl groups increase acidity. �� Therefore they are acidic amino acids.

✅ Correct Answer Explanation

Aspartic acid and glutamic acid contain more carboxyl groups than amino groups. This excess acidic functionality causes them to be classified as acidic amino acids.

❓ Why Other Options Are Incorrect

�� Option B → Basic amino acids contain extra amino groups.
�� Option C → Neutral amino acids have equal amino and carboxyl groups.
�� Option D → All amino acids are amphoteric but this is not their classification here.

🎯 Strategy

Used

Classification

Application:

Compare amino and carboxyl group numbers.

Final Logic:

Extra COOH groups indicate acidic amino acids.

🧠 Memory Trick

Aspartic & Glutamic = Acidic Duo

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Acidic Amino Acids

9 What structural ratio accurately dictates that an amino acid like valine is classified as neutral?

A It possesses a 1:2 ratio of amino to carboxyl groups.

B It possesses a 1:1 ratio of amino to carboxyl groups.

C It possesses a 2:1 ratio of amino to carboxyl groups.

D It lacks a carboxyl group entirely.

💡 Short Explanation

�� Neutral amino acids contain one amino group. �� They also contain one carboxyl group. �� Therefore the ratio is 1:1.

✅ Correct Answer Explanation

Valine contains one amino group and one carboxyl group. Since the numbers of acidic and basic groups are equal, valine is classified as a neutral amino acid.

❓ Why Other Options Are Incorrect

�� Option A → Indicates acidic character.
�� Option C → Indicates basic character.
�� Option D → Impossible for an amino acid.

🎯 Strategy

Used

Structural Analysis

Application:

Compare functional group numbers.

Final Logic:

Neutral amino acids have a 1:1 ratio.

🧠 Memory Trick

Neutral = One NH₂, One COOH

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Neutral Amino Acids

10 At its isoelectric point (neutral zwitter ion state in aqueous solution), the net electrical charge on a neutral amino acid molecule is exactly:

A +1 e

B -1 e

C 0 e

D +2 e

💡 Short Explanation

�� Positive and negative charges are both present. �� They balance each other exactly. �� Net charge becomes zero.

✅ Correct Answer Explanation

At the isoelectric point, amino acids exist predominantly as zwitter ions. The positive charge on the protonated amino group is balanced by the negative charge on the carboxylate ion, resulting in a net charge of zero.

❓ Why Other Options Are Incorrect

�� Option A → Positive charge is balanced.
�� Option B → Negative charge is balanced.
�� Option D → No such net charge exists at the isoelectric point.

🎯 Strategy

Used

Concept Application

Application:

Understand the zwitter ionic form.

Final Logic:

Equal positive and negative charges give zero net charge.

🧠 Memory Trick

Isoelectric = Zero Net Charge

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Isoelectric Point and Zwitter Ions

11 The destruction of the secondary and tertiary structure of a native protein (unfolding of globules and uncoiling of helices) while keeping the primary structure intact is identified as which reaction process?

A Hydrolysis

B Denaturation

C Polymerisation

D Condensation

💡 Short Explanation

�� Secondary and tertiary structures are disrupted. �� Peptide bonds remain unaffected. �� The protein loses its biological activity.

✅ Correct Answer Explanation

Denaturation refers to the unfolding of the native protein structure due to factors such as heat or changes in pH. During this process, the secondary and tertiary structures are destroyed, while the primary structure remains intact because peptide bonds are not broken.

❓ Why Other Options Are Incorrect

�� Option A → Hydrolysis breaks peptide bonds.
�� Option C → Polymerisation forms larger molecules.
�� Option D → Condensation forms peptide bonds.

🎯 Strategy

Used

Concept Identification

Application:

Identify the process affecting higher-order protein structures.

Final Logic:

Loss of secondary and tertiary structures = Denaturation.

🧠 Memory Trick

Denaturation = Unfolding Without Breaking the Chain

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Denaturation of Proteins

12 Amino acids behave physically like salts (water-soluble, high melting solids) rather than simple amines or carboxylic acids due directly to the formation of:

A Peptide bonds

B Glycosidic linkages

C Zwitter ions

D Alpha helices

💡 Short Explanation

�� Amino acids contain both positive and negative charges. �� They exist as dipolar ions in solution. �� This gives them salt-like properties.

✅ Correct Answer Explanation

In aqueous solution, amino acids exist predominantly as zwitter ions containing both a positively charged ammonium group and a negatively charged carboxylate group. This ionic nature gives them high melting points and water solubility similar to salts.

❓ Why Other Options Are Incorrect

�� Option A → Found in proteins, not free amino acids.
�� Option B → Found in carbohydrates.
�� Option D → Protein secondary structure.

🎯 Strategy

Used

Property Analysis

Application:

Relate physical properties to ionic structure.

Final Logic:

Zwitter ions cause salt-like behavior.

🧠 Memory Trick

Zwitter Ion = Salt-Like Amino Acid

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Zwitter Ionic Nature of Amino Acids

📄 Passage

When a protein in its native form is subjected to physical change like a change in temperature or chemical change like a change in pH, the hydrogen bonds are disturbed. Due to this, globules unfold and the helix gets uncoiled, and the protein loses its biological activity. This is called denaturation of protein. During denaturation, secondary and tertiary structures are destroyed but primary structure remains intact. The coagulation of egg white on boiling is a common example of denaturation.

Based on the passage, which structural level of a protein sequence, held together by peptide bonds, remains completely intact during denaturation?

A Primary structure

B Secondary structure

C Tertiary structure

D Quaternary structure

💡 Short Explanation

�� Peptide bonds are not broken. �� Amino acid sequence remains unchanged. �� Therefore, the primary structure is preserved.

✅ Correct Answer Explanation

Denaturation disrupts hydrogen bonds and other weak interactions responsible for secondary and tertiary structures. However, peptide bonds remain intact, so the amino acid sequence (primary structure) remains unchanged.

❓ Why Other Options Are Incorrect

�� Option B → Destroyed during denaturation.
�� Option C → Destroyed during denaturation.
�� Option D → Can also be disrupted.

🎯 Strategy

Used

Passage-Based Analysis

Application:

Identify the structural level unaffected by denaturation.

Final Logic:

Primary structure remains intact.

🧠 Memory Trick

Denaturation Stops at Primary Structure

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Denaturation and Protein Structure

📄 Passage

Passage
When a protein in its native form is subjected to physical change like a change in temperature or chemical change like a change in pH, the hydrogen bonds are disturbed. Due to this, globules unfold and the helix gets uncoiled, and the protein loses its biological activity. This is called denaturation of protein. During denaturation, secondary and tertiary structures are destroyed but primary structure remains intact. The coagulation of egg white on boiling is a common example of denaturation.

Based on the passage, the coagulation of egg white on boiling is a classic example of which phenomenon?

A Hydrolysis

B Polymerisation

C Zwitter ion formation

D Denaturation

💡 Short Explanation

Heat disrupts protein structure.
Egg white proteins unfold and coagulate.
This is denaturation.

✅ Correct Answer Explanation

Boiling egg white causes protein molecules to lose their native structure and biological activity. This unfolding and coagulation of proteins is a classic example of denaturation.

❓ Why Other Options Are Incorrect

Option A → No peptide bond cleavage occurs.
Option B → No polymer formation occurs.
Option C → Unrelated to protein coagulation.

🎯 Strategy

Example Identification

Application:

Recognize a common example of denaturation.

Final Logic:

Coagulated egg white = Denatured protein.

🧠 Memory Trick

Boiled Egg = Denatured Protein

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Examples of Denaturation

📄 Passage

Based on the passage, the coagulation of egg white on boiling is a classic example of which phenomenon?

A Hydrolysis

B Polymerisation

C Zwitter ion formation

D Denaturation

💡 Short Explanation

�� Heat disrupts protein structure. �� Egg white proteins unfold and coagulate. �� This is denaturation.

✅ Correct Answer Explanation

Boiling egg white causes protein molecules to lose their native structure and biological activity. This unfolding and coagulation of proteins is a classic example of denaturation.

❓ Why Other Options Are Incorrect

�� Option A → No peptide bond cleavage occurs.
�� Option B → No polymer formation occurs.
�� Option C → Unrelated to protein coagulation.

🎯 Strategy

Used

Example Identification

Application:

Recognize a common example of denaturation.

Final Logic:

Coagulated egg white = Denatured protein.

🧠 Memory Trick

Boiled Egg = Denatured Protein

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Examples of Denaturation

15 What specific type of chemical reaction occurs when hundreds of amino acids link together to form a polypeptide, losing water molecules in the process?

A Addition reaction

B Condensation / Elimination reaction

C Substitution reaction

D Oxidation reaction

💡 Short Explanation

�� Amino acids join through peptide bonds. �� Water molecules are removed. �� Such reactions are condensation reactions.

✅ Correct Answer Explanation

Formation of peptide bonds between amino acids occurs through the elimination of water molecules. Therefore, the process is classified as a condensation (or elimination) reaction.

❓ Why Other Options Are Incorrect

�� Option A → No direct addition occurs.
�� Option C → Not a substitution process.
�� Option D → No oxidation state change occurs.

🎯 Strategy

Used

Reaction Identification

Application:

Recognize peptide bond formation chemistry.

Final Logic:

Loss of water indicates condensation.

🧠 Memory Trick

Peptide Bond = Condensation

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Formation of Polypeptides

16 Insulin is technically classified as a protein despite having only 51 amino acids (fewer than the typical 100). This is primarily because:

A It has an exceptionally high molecular mass.

B It ordinarily has a well-defined native conformation.

C It entirely lacks a primary sequence.

D It is a purely essential amino acid.

💡 Short Explanation

�� Insulin has a stable three-dimensional structure. �� It performs a specific biological function. �� Therefore it is classified as a protein.

✅ Correct Answer Explanation

Although insulin contains only 51 amino acid residues, it possesses a definite native conformation and biological activity. Such molecules are considered proteins despite being smaller than many typical proteins.

❓ Why Other Options Are Incorrect

�� Option A → Not the defining reason.
�� Option C → All proteins have a primary sequence.
�� Option D → Insulin is not an amino acid.

🎯 Strategy

Used

Concept Application

Application:

Distinguish proteins from simple polypeptides.

Final Logic:

Native conformation defines protein behavior.

🧠 Memory Trick

Insulin = Small but Functional Protein

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Proteins and Polypeptides

17 Regarding the secondary structure of proteins, which of the following statements are correct?
1. It refers to the specific sequence of amino acids.
2. It exists mainly as α-helix or β-pleated sheet forms.
3. These structures arise due to regular folding of the polypeptide backbone.
4. It is primarily stabilized by strong glycosidic linkages.

A 2 and 3

B 1 and 2

C 3 and 4

D 1, 3 and 4

💡 Short Explanation

�� Secondary structure includes α-helices and β-sheets. �� It results from regular folding patterns. �� Hydrogen bonds stabilize these structures.

✅ Correct Answer Explanation

Statement 1 is incorrect because amino acid sequence defines primary structure. Statement 2 is correct because α-helices and β-pleated sheets are common secondary structures. Statement 3 is correct because secondary structures arise from regular folding of the backbone. Statement 4 is incorrect because stabilization occurs mainly through hydrogen bonds, not glycosidic linkages. Therefore, Statements 2 and 3 are correct.

❓ Why Other Options Are Incorrect

�� Option B → Statement 1 is incorrect.
�� Option C → Statement 4 is incorrect.
�� Option D → Includes incorrect Statements 1 and 4.

🎯 Strategy

Used

Statement Verification

Application:

Differentiate primary and secondary structures.

Final Logic:

Only Statements 2 and 3 are correct.

🧠 Memory Trick

Secondary = Helix + Sheet

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Secondary Structure of Proteins

18 Match the chemical bond or force with the primary structural level it dictates/stabilizes.

List I	List II
1. — Covalent peptide bonds	a. — Secondary Structure
2. — Hydrogen bonding between –C=O and –NH– groups	b. — Primary Structure

A 1-b, 2-a

B 1-a, 2-b

C 1-a, 2-a

D 1-b, 2-b

💡 Short Explanation

�� Peptide bonds create the amino acid sequence. �� Hydrogen bonds stabilize helices and sheets.

✅ Correct Answer Explanation

Matching: 1. Covalent peptide bonds → Primary Structure 2. Hydrogen bonding between peptide groups → Secondary Structure Thus: 1-b, 2-a

❓ Why Other Options Are Incorrect

�� Options B, C and D incorrectly assign the structural levels.

🎯 Strategy

Used

Matching

Application:

Associate bonding type with structural level.

Final Logic:

Peptide bonds → Primary, Hydrogen bonds → Secondary.

🧠 Memory Trick

Peptide = Primary, Hydrogen = Secondary

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Protein Structural Levels

19 The further folding of a secondary structure into a tertiary structure gives rise to two major molecular shapes known as:

A Primary and secondary

B Fibrous and globular

C Acidic and basic

D Dextro and laevo

💡 Short Explanation

�� Tertiary structure determines overall shape. �� Proteins are commonly fibrous or globular. �� Shape influences biological function.

✅ Correct Answer Explanation

The tertiary structure results from further folding of secondary structures and produces characteristic protein shapes. The two major categories are fibrous proteins and globular proteins.

❓ Why Other Options Are Incorrect

�� Option A → Structural levels, not shapes.
�� Option C → Amino acid classifications.
�� Option D → Optical activity terms.

🎯 Strategy

Used

Concept Recall

Application:

Identify the major protein shapes.

Final Logic:

Tertiary structure produces fibrous and globular forms.

🧠 Memory Trick

Tertiary = Fibrous or Globular

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Tertiary Structure of Proteins

20 Arrange the architectural structural levels of a complex functional protein in decreasing order of overall 3D structural complexity:
A. Secondary structure
B. Quaternary structure
C. Primary structure
D. Tertiary structure

A B, D, A, C

B A, B, C, D

C D, B, A, C

D C, A, D, B

💡 Short Explanation

Quaternary structure is the most complex.
Tertiary structure follows.
Secondary and primary structures are progressively simpler.

✅ Correct Answer Explanation

The hierarchy of protein structure complexity is:

Quaternary Structure > Tertiary Structure > Secondary Structure > Primary Structure

Therefore:

B → D → A → C

❓ Why Other Options Are Incorrect

Options B, C and D do not follow the accepted hierarchy.

🎯 Strategy

Ordering

Application:

Arrange protein structures from most complex to simplest.

Final Logic:

Quaternary > Tertiary > Secondary > Primary.

🧠 Memory Trick

Q → T → S → P

📚 Class XII – Chemistry Part II – Chapter: Biomolecules – Topic: Hierarchy of Protein Structure

CUET UG Chemistry Booster Test – 2 Proteins and Amino Acids

CUET UG Chemistry Booster Test - 1 Proteins and Amino Acids

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