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Macromolecules / Biochemistry Past Papers
Solved past paper MCQs for Macromolecules / Biochemistry from official UHS, NUMS, SZABMU, DUHS, and KMU examinations. Includes verified distractor autopsies and step-by-step cognitive explanations.
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Official printable A4 booklet containing all 40 verified past paper MCQs with unbroken options, 5-column rapid answer key, and Propolis cognitive error autopsies.
Thyroxin is an amino acid derivative acting as a systemic chemical messenger.
Formula:
$$N/A$$
Solution:
Thyroxin (T4) is secreted into the blood by the thyroid gland to regulate basal metabolic rate.
Because its physiological role is entirely regulatory and acts at distant target tissues, it is functionally classified as a hormonal protein (or hormonal derivative).
Why other options are incorrect:
It is not used to build tissues (structural), it doesn't ferry other molecules in the blood (transport), and it is not a histone involved in DNA packing (genetic).
The erythrocytes (red blood cells) are packed with a specialized iron-containing protein called hemoglobin.
Hemoglobin binds oxygen tightly in the high-oxygen environment of the lungs and releases it in the lower-oxygen environment of peripheral tissues.
Why other options are incorrect:
While hemoglobin is a protein, "Proteins" is far too broad of an answer. Hormones regulate physiology, and liquids (like blood plasma) carry only a negligible amount of dissolved oxygen compared to hemoglobin.
Deficiency of ____ causes loss of weight, appetite, and taste: (out of syllabus)
A
P
B
Zn
C
Fe
D
K
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Trace minerals and macronutrients play crucial roles in physiological homeostasis. Phosphorus (P) is vital for ATP, bone structure, and cellular signaling.
Formula:
$$N/A$$
Solution:
According to the provided explanatory notes for this specific exam, a deficiency of Phosphorus (P) is linked to a cluster of symptoms including loss of weight, appetite, and taste.
Note: In clinical medicine, Zinc (Zn) deficiency is most classically famous for causing loss of taste (ageusia) and appetite. However, strictly following the provided board curriculum/key, Phosphorus is the indicated answer.
Why other options are incorrect:
Iron (Fe) deficiency causes anemia (fatigue, pale skin). Potassium (K) deficiency causes muscle weakness and fatigue. Zinc (Zn) causes skin rashes and diarrhea according to the provided text.
Amino acids, which are not synthesized by human body are
A
Synthetic amino acids
B
Non-essential amino acids
C
Dietary amino acids
D
Essential amino acids
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Nutritional classification of amino acids is based on the body's intrinsic biochemical ability to synthesize them from intermediate metabolites.
Formula:
$$N/A$$
Solution:
The human body requires 20 standard amino acids to build proteins.
The body can manufacture 11 of them internally (non-essential).
The remaining 9 amino acids cannot be synthesized by human metabolic pathways. Because it is "essential" that they are obtained through the diet, they are called essential amino acids (e.g., valine, histidine, leucine).
Why other options are incorrect:
Non-essential amino acids are synthesized by the body. 'Dietary' is a generic term, and 'synthetic' implies artificially created in a lab rather than naturally derived from food.
When a polymer chain consists entirely of copies of exactly one type of monomer, it is referred to as a homopolymer (homo- meaning 'same').
Examples include polyethylene (only ethene monomers) or starch (only glucose monomers).
Why other options are incorrect:
A copolymer consists of two different types of monomers (like Nylon-6,6). A terpolymer consists of three different monomers. A thermosetting polymer refers to cross-linking response to heat, not monomer composition.
The lipids which have ____ compound is called steroids
A
Tetracyclic
B
Phenanthrene
C
Benzene
D
Cyclopentane
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Correct Key: Option ADiagnostic Explanation
Concept:
Steroids are a unique class of lipids defined by their rigid, multi-ring structural backbone rather than fatty acid chains.
Formula:
$$N/A$$
Solution:
All steroids (like cholesterol, testosterone, estrogen) share a core chemical structure known as the gonane skeleton.
This skeleton consists of three six-membered rings (cyclohexane) and one five-membered ring (cyclopentane) fused together.
Because there are exactly four fused rings, this core is defined as a tetracyclic compound (specifically, cyclopentanoperhydrophenanthrene).
Why other options are incorrect:
While the steroid nucleus contains a cyclopentane ring and a phenanthrene-like backbone, "tetracyclic" is the precise term describing the entirety of the four-ring compound. Benzene rings are aromatic and do not define the fully saturated steroid nucleus.
The protein portion of the enzyme is the apoenzyme.
The non-protein portion required for activity is broadly called a cofactor.
When this non-protein part is specifically an organic molecule (often derived from vitamins, like NAD+ or FAD), it is referred to as a co-enzyme.
Why other options are incorrect:
The apoenzyme is the protein part, not the non-protein part. The substrate is the target molecule being acted upon. An activator is a substance that increases activity, but "co-enzyme" strictly defines the intrinsic non-protein prosthetic/helper group.
The two functional groups present in all amino acids are:
A
Carboxylic acid and amino
B
Amino and aldehyde
C
Ether and carboxylic acid
D
Aldehyde and carboxylic acid
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
An \( \alpha \)-amino acid has a specific, highly conserved core structure surrounding a central chiral carbon atom.
Formula:
$$ \text{H}_2\text{N-CH(R)-COOH} $$
Solution:
Every amino acid has a central \( \alpha \)-carbon bonded to a hydrogen atom and an R-group side chain.
Crucially, it is bonded to a basic amino group (\( \text{-NH}_2 \)) and an acidic carboxyl group (\( \text{-COOH} \)).
Hence, the two defining functional groups are carboxylic acid and amino groups.
Why other options are incorrect:
Aldehydes and ethers are not part of the standard amino acid backbone. While some specific R-groups might contain complex functionalities, only the amino and carboxyl groups are universally present in all amino acids.
Enzymes are biological catalysts produced by living cells to facilitate biochemical reactions.
Formula:
$$ k = A e^{-\frac{E_a}{RT}} $$
Solution:
By providing an alternative reaction pathway with a lower activation energy (\( E_a \)), enzymes allow more substrate molecules to convert into product per unit time.
Therefore, they fundamentally increase the rate of chemical reaction.
Why other options are incorrect:
Enzymes do not decrease or stop reactions (that is the role of inhibitors). Since life depends on rapid metabolic processes, claiming they have "no effect" is biologically false.
The inhibition in which or inhibitor does not combine directly with the enzyme but binds to the enzyme substrate complex is called:
A
Reversible inhibition
B
Competitive inhibition
C
Uncompetitive inhibition
D
Non-competitive inhibition
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
In enzyme kinetics, inhibitors can bind to the free enzyme, the enzyme-substrate (ES) complex, or both. The specific binding target defines the kinetic pattern.
If an inhibitor exclusively binds to the Enzyme-Substrate (ES) complex (and has zero affinity for the free enzyme), it locks the substrate inside and prevents product formation.
This specific mechanism is defined as uncompetitive inhibition.
Why other options are incorrect:
Competitive inhibitors bind only to the free enzyme. Non-competitive inhibitors can bind to both the free enzyme AND the ES complex equally. Reversible inhibition is a broad category that includes all of these.
Proteases are secreted as inactive zymogens (proenzymes) to prevent them from digesting the organs that synthesize them. They require a specific activator in the gut.
Enzyme show optimum activity between 37°C to 50°C. it however works
A
Below 37°C
B
Above 50°C
C
It loses activity permanently below 37°C
D
It loses activity permanently above 50°C
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Enzymes are proteinaceous catalysts that rely on a specific 3D folded structure. High temperatures impart excess kinetic energy, breaking the weak non-covalent bonds holding this structure together.
Formula:
$$N/A$$
Solution:
As temperature increases up to 50°C, enzyme activity typically increases (reaching an optimum).
However, pushing temperatures above this optimum range (typically above 50°C - 60°C for human enzymes) violently disrupts hydrogen bonds and hydrophobic interactions.
This leads to thermal denaturation, unfolding the active site. Because the protein coagulates and unfolds irreversibly, it loses activity permanently above 50°C.
Why other options are incorrect:
Below 37°C, enzyme activity decreases due to low kinetic energy, but it does NOT lose activity permanently (it regains activity when warmed). It definitely does not "work" above 50°C once denatured.
Among the choices, aspartic acid (aspartate) is one of the standard 20 naturally occurring \( \alpha \)-amino acids used to synthesize proteins.
Its R-group is a \( \text{-CH}_2\text{-COOH} \) group, making it an acidic amino acid.
Why other options are incorrect:
Palmitic acid is a 16-carbon saturated fatty acid. Benzoic acid is an aromatic carboxylic acid. Aniline is an aromatic amine (phenylamine). None of these possess the dual amino-carboxyl backbone of an amino acid.
For every reaction occurring in human body there is at least one type of:
A
Protein
B
Enzyme
C
Amino acid
D
Vitamin
View Answer & Propolis Autopsy
Correct Key: Option BDiagnostic Explanation
Concept:
Biological systems maintain homeostasis and rapid metabolism at low body temperatures by using highly specific biological catalysts.
Formula:
$$N/A$$
Solution:
Without catalysis, biochemical reactions in the human body would occur far too slowly to sustain life at 37°C.
To overcome activation energy barriers, enzymes are utilized.
Enzymes are highly specific; thus, for virtually every discrete metabolic reaction in the body, there exists a specific enzyme to catalyze it.
Why other options are incorrect:
While all enzymes are proteins (and thus made of amino acids), saying "protein" is too broad, as many proteins (like keratin) do not catalyze reactions. Vitamins act as coenzymes, but not every reaction requires a vitamin coenzyme.
When food reaches stomach, the action of which of the following come to an end due to acidic pH?
A
Amylase
B
Lipase
C
Maltase
D
Hydrolase
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Correct Key: Option ADiagnostic Explanation
Concept:
Enzymes have a strict optimum pH range. Deviating drastically from this pH alters the active site's ionization state and denatures the enzyme.
Formula:
$$N/A$$
Solution:
Digestion of carbohydrates begins in the mouth with salivary amylase (ptyalin), which functions optimally at a nearly neutral pH (approx 6.8).
When the swallowed food bolus reaches the stomach, it encounters gastric juice containing hydrochloric acid (pH 1.5 - 2.5).
This highly acidic environment immediately denatures salivary amylase, bringing its carbohydrate-digesting action to an end.
Why other options are incorrect:
Gastric lipase actually functions in the acidic environment of the stomach. Maltase acts later in the slightly alkaline environment of the small intestine. 'Hydrolase' is a broad class of enzymes, some of which (like pepsin) thrive in acidic pH.
Which of the following proteins acts as carrier of Cu in blood plasma?
A
Ceruloplasmin
B
Haemoglobin
C
Glycoprotein
D
Histone
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Specific transport proteins in the blood plasma are responsible for safely carrying metal ions to prevent toxicity and facilitate systemic delivery.
Formula:
$$N/A$$
Solution:
Copper (Cu) is a vital trace mineral, but free copper ions are highly toxic.
In the blood plasma, over 90% of circulating copper is bound to a specific transport and ferroxidase protein called ceruloplasmin.
Why other options are incorrect:
Haemoglobin carries oxygen and contains iron (Fe), not copper. Histones are nuclear proteins that pack DNA. Glycoprotein is a broad structural category (though ceruloplasmin is technically a glycoprotein, 'ceruloplasmin' is the exact, specific carrier name).
Biomolecules (including amino acid derivatives) are classified by their physiological roles, such as transport, structure, or regulation.
Formula:
$$N/A$$
Solution:
Thyroxin (T4) is secreted by the thyroid gland and travels through the bloodstream to target organs, regulating base metabolic rate.
Because it functions as a chemical messenger regulating body processes, it falls under the functional classification of a hormonal protein (or biologically active amino acid derivative).
Why other options are incorrect:
It does not provide physical structure (structural), transport molecules like oxygen (transport), or interact directly with DNA packaging (genetic).
Enzymes are biological catalysts produced by living cells to facilitate biochemical reactions.
Formula:
$$ k = A e^{-\frac{E_a}{RT}} $$
Solution:
By providing an alternative reaction pathway with a lower activation energy (\( E_a \)), enzymes allow more substrate molecules to convert into product per unit time.
Therefore, they fundamentally increase the rate of chemical reaction.
Why other options are incorrect:
Enzymes do not decrease or stop reactions (that is the role of inhibitors). Since life depends on rapid metabolic processes, claiming they have "no effect" is biologically false.
The linear arrangement of amino acid units in proteins is called:
A
Primary structure
B
Secondary structure
C
Tertiary structure
D
Quaternary structure
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Protein architecture is organized from simple 1D sequences up to complex 3D multi-subunit structures.
Formula:
$$N/A$$
Solution:
The most basic level of protein structure is the simple, straight-chain sequence of amino acids linked end-to-end by covalent peptide bonds.
This specific linear arrangement is termed the primary structure.
Why other options are incorrect:
Secondary structure involves coiling into helices/sheets. Tertiary structure involves 3D folding of those helices/sheets. Quaternary involves the aggregation of multiple folded chains.
Nylon-6,6 is synthesized from two monomers: adipic acid (hexanedioic acid) and hexamethylenediamine (1,6-diaminohexane).
Both monomers contain 6 carbon atoms, hence the name "6,6".
Water is eliminated during bond formation, making it a condensation polymer of hexandioic acid & 1,6-diaminohexane. (While D is technically true, A is the most specific and accurate description).
Why other options are incorrect:
Addition polymers form without the loss of small molecules (e.g., polyethylene). Nylon contains amide bonds (\( \text{-CO-NH-} \)), so it is a polyamide, not a polyester.
Macromolecules utilize specific covalent bonds to link their respective monomers.
Formula:
$$ \text{-CO-NH-} $$
Solution:
The carboxyl group of one amino acid reacts with the amino group of another, releasing water.
The resulting amide bond (\( \text{-CO-NH-} \)) in biochemistry is universally called a peptide linkage.
Why other options are incorrect:
Glycosidic linkages join monosaccharides together to form carbohydrates. Glucoacidic is not a standard biochemical term. Ethane linkages imply carbon-carbon alkane bonds, which do not link amino acid backbones.
Which enzyme is used for the treatment of blood cancer in children?
A
Thrombin
B
LDH-1
C
L-asparaginase
D
Zymase
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Enzyme therapy leverages the metabolic weaknesses of specific cancer cells.
Formula:
$$N/A$$
Solution:
Childhood acute lymphoblastic leukemia (blood cancer) cells require circulating L-asparagine for survival because they lack the enzyme to synthesize it themselves.
By injecting L-asparaginase into the patient, the circulating L-asparagine is hydrolyzed into aspartic acid and ammonia.
Starved of this essential amino acid, the cancer cells undergo apoptosis (programmed cell death).
Why other options are incorrect:
Thrombin is used locally to stop bleeding. LDH-1 levels are diagnostic markers for heart attacks. Zymase is a yeast enzyme used in ethanol fermentation.
The defining chemical characteristic of a protein is its polyamide backbone.
Formula:
$$ \text{-CO-NH-} $$
Solution:
Proteins consist of amino acids attached end-to-end.
This continuous covalent chain is formed entirely by peptide linkages (amide bonds). This makes the peptide bond the central structural feature of all proteins.
Why other options are incorrect:
Ester linkages form lipids (triglycerides). Glycoside linkages form polysaccharides (carbohydrates). Ether linkages (\( \text{R-O-R'} \)) are not the primary backbone of biological macromolecules.
Macromolecules are composed of repeating monomeric units. Proteins are one of the four major classes of biological macromolecules.
Formula:
$$N/A$$
Solution:
Proteins are complex, high-molecular-weight organic compounds.
They are built from chains of amino acids connected by peptide bonds. Hence, amino acids are the monomers of proteins.
Why other options are incorrect:
Glucose is the monomer of carbohydrates (like starch and cellulose). Nitrogenous bases are components of nucleotides (the monomers of nucleic acids). While proteins contain nitrogen atoms, "nitrogen atoms" themselves are not polymeric units.
The question states that globulins yield only amino acids (or their direct derivatives) upon hydrolysis and do not yield any non-protein prosthetic groups.
By definition, macromolecules that yield only amino acids upon hydrolysis are classified as simple proteins.
Why other options are incorrect:
Compound and conjugated proteins are synonymous; both yield non-protein prosthetic groups (like lipids or carbohydrates) alongside amino acids. Derived proteins are denatured or partially broken-down proteins, whereas globulins are native functional proteins.
Regular coiling and twisting of polypeptide chain caused by H-bonding in between NH and CO occurs ____
A
Tertiary structure
B
Primary structure
C
Secondary structure
D
Quaternary structure
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Protein structure is organized hierarchically into primary, secondary, tertiary, and quaternary levels.
Formula:
$$N/A$$
Solution:
The primary structure is the linear sequence of amino acids (covalent peptide bonds).
When this linear chain begins to fold, it forms regular local patterns such as \( \alpha \)-helices (coiling) and \( \beta \)-pleated sheets (twisting/folding).
This localized folding is entirely stabilized by regular hydrogen bonds between the \( \text{N-H} \) and \( \text{C=O} \) groups of the peptide backbone. This level is defined as the secondary structure.
Why other options are incorrect:
Primary structure involves no H-bonding. Tertiary structure is the overall 3D folding stabilized by R-group interactions (disulfide, ionic, hydrophobic). Quaternary structure involves multiple polypeptide chains assembling together.
The substances which reduce the activity of enzyme action are called ____?
A
Activators
B
Promotors
C
Reducers
D
Inhibitors
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Enzyme activity can be modulated by various small molecules that bind to the enzyme.
Formula:
$$N/A$$
Solution:
Chemical substances that bind to an enzyme (either at the active site or an allosteric site) and subsequently decrease or halt its catalytic activity are termed inhibitors.
Inhibition can be competitive, non-competitive, or uncompetitive.
Why other options are incorrect:
Activators and promoters increase enzyme activity or gene expression, respectively. Reducers are chemical agents that donate electrons in redox reactions, not a term used specifically for reducing enzyme kinetics.
Proteins/amino acid derivatives perform vastly different functional roles in the body, such as structure, transport, catalysis, or signaling.
Formula:
$$N/A$$
Solution:
Thyroxin (T4) is an iodine-containing hormone derived from the amino acid tyrosine.
It is secreted by the thyroid gland and circulates in the blood to regulate metabolism.
Functionally, because it acts as a chemical messenger regulating physiological processes, it is classified functionally under the category of hormonal proteins (or amino-acid derived hormones).
Why other options are incorrect:
Structural proteins (like collagen) provide physical support. Transport proteins (like hemoglobin) move molecules. Genetic proteins (like histones) bind to DNA. Thyroxin performs none of these functions; it is purely regulatory/hormonal.
L-asparaginase breaks down the amino acid L-asparagine.
Normal cells can synthesize their own L-asparagine, but certain leukemic (blood cancer) cells in children cannot.
Administering L-asparaginase depletes circulating L-asparagine, starving the cancer cells and causing their death. Thus, it is highly effective in treating childhood blood cancer (acute lymphoblastic leukemia).
Why other options are incorrect:
Jaundice is related to bilirubin processing. Rickets is caused by Vitamin D/calcium deficiency. Heart disease is treated with other agents (like tissue plasminogen activator). None of these involve L-asparaginase.
A conjugated protein is a complex protein consisting of an amino acid chain (the apoprotein) attached to a non-protein part called a prosthetic group.
Upon complete hydrolysis, it yields both the constituent amino acids and the free prosthetic group (e.g., a lipid, carbohydrate, or metal ion).
Why other options are incorrect:
Simple proteins (like albumins) yield only amino acids upon hydrolysis. Derived proteins are partially degraded proteins. 'Conjugated simple protein' is a contradictory, non-standard term.
Saliva contains an enzyme called salivary amylase, historically and specifically referred to as ptyalin.
Ptyalin accelerates the breakdown of the polysaccharide starch into simpler sugars (like maltose and dextrins).
Why other options are incorrect:
Pepsin is a protease found in the stomach that digests proteins. Thrombin is involved in blood clotting. Fumarase is an enzyme in the Krebs cycle. None of these act on starch in the saliva.
Which of the following bond is responsible for joining the amino acids in proteins?
A
Peptide Bond
B
Metallic Bond
C
Di sulfide bond
D
Ionic Bond
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
The primary structure of a protein is defined by the linear sequence of amino acids linked together by covalent bonds.
Formula:
$$ \text{-CO-NH-} $$
Solution:
During translation in ribosomes, amino acids undergo a condensation reaction.
The carboxyl group of one amino acid reacts with the amino group of the next, releasing water and forming a covalent amide linkage known specifically as a peptide bond.
Why other options are incorrect:
Disulfide bonds connect cysteine residues to stabilize tertiary structure but do not form the main primary backbone between all amino acids. Ionic and metallic bonds are not the linkages that polymerize amino acids.
The stability in the following structure is due to the
A
Hydrogen bonding between NH group of one peptide with another peptide
B
Disulfide bridges
C
Weak vander Waal's forces
D
Presence of unpaired electron in the structure
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
The secondary structure of proteins (like the \( \alpha \)-helix or \( \beta \)-pleated sheet) is stabilized by specific non-covalent interactions along the polypeptide backbone.
Formula:
$$ \text{>C=O} \cdots \text{H-N<} $$
Solution:
The given structure (\( \alpha \)-helix) maintains its coiled shape because of regular hydrogen bonds.
These hydrogen bonds form between the carbonyl oxygen (\( \text{C=O} \)) of one amino acid residue and the amide hydrogen (\( \text{N-H} \)) of another residue four positions down the chain.
Why other options are incorrect:
Disulfide bridges are covalent bonds that stabilize tertiary structure. Van der Waals forces contribute to tertiary packing, but H-bonds specifically define secondary structure. Unpaired electrons are irrelevant here.
Amino acids react with each other such that -COOH group of one amino acid reacts with the another amino acid to give a condensed structure as shown below. What is the name of circled part of this structure?
A
Ester linkage
B
Azide linkage
C
Peptide linkage
D
Carbide linkage
View Answer & Propolis Autopsy
Correct Key: Option CDiagnostic Explanation
Concept:
Proteins are formed through dehydration condensation reactions between amino acids, resulting in a specific amide bond.
The reaction between the carboxylic acid group (\( \text{-COOH} \)) of one amino acid and the amino group (\( \text{-NH}_2 \)) of a second amino acid releases a water molecule.
The resulting \( \text{-CO-NH-} \) bond linking the two amino acids is biochemically referred to as a peptide linkage (or peptide bond).
Why other options are incorrect:
Ester linkages (\( \text{-COO-} \)) are found in lipids, linking fatty acids to glycerol. Azide (\( \text{-N}_3 \)) and carbide are entirely different chemical groups not found in the protein backbone.
Conjugated proteins consist of an amino acid chain (protein part) attached to a non-protein prosthetic group.
Formula:
$$N/A$$
Solution:
Phosphoproteins yield amino acids and phosphoric acid upon hydrolysis.
Because phosphoric acid serves as a non-protein prosthetic group covalently bound to the protein, phosphoproteins are classified as conjugated proteins.
Why other options are incorrect:
Simple proteins lack a prosthetic group entirely. Derived proteins are altered or degraded forms of native proteins. Therefore, 'Both A & B' is also incorrect.
Macromolecules are described as large molecules built up from small repeating units called
A
Monomers
B
Metamers
C
Isomers
D
Tautomers
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Polymer chemistry involves the formation of large macromolecules from smaller fundamental building blocks.
Formula:
$$N/A$$
Solution:
A macromolecule (or polymer) is synthesized by covalently bonding many smaller, repeating structural units together.
These fundamental repeating units are called monomers (from Greek mono meaning 'one' and meros meaning 'part').
Why other options are incorrect:
Metamers, isomers, and tautomers are types of molecules with the same molecular formula but different structural arrangements; they do not refer to the repeating units of a polymer.
A polymer in which the number of amino acid residue is greater than 100 or the molecular mass is greater than 10,000 is called
A
Polypeptide
B
Tripeptide
C
Dipeptide
D
Protein
View Answer & Propolis Autopsy
Correct Key: Option DDiagnostic Explanation
Concept:
Amino acids polymerize via peptide bonds. The nomenclature (peptide vs. protein) depends on the length of the chain and molecular weight.
Formula:
$$N/A$$
Solution:
A dipeptide has 2 amino acids, a tripeptide has 3, and a polypeptide typically has up to 100 amino acids.
By biochemical definition, a macromolecule with more than 100 amino acid residues or a molecular mass exceeding 10,000 Daltons (10 kDa) is officially termed a protein.
Why other options are incorrect:
A polypeptide refers to chains shorter than 100 amino acids. Dipeptides and tripeptides consist of only 2 and 3 amino acids, respectively.
Proteins are classified into simple, conjugated, and derived proteins based on their composition and hydrolysis products. Simple proteins yield only amino acids upon hydrolysis.
Formula:
$$N/A$$
Solution:
Collagen (a structural protein in connective tissues) and albumin (a globular blood protein) consist entirely of amino acid sequences.
Upon hydrolysis, they yield only amino acids and no non-protein (prosthetic) groups, making them simple proteins.
Why other options are incorrect:
Derived proteins are products of partial hydrolysis of proteins (like peptones). Polyamides can be synthetic (like nylon), and polysaccharides are carbohydrates, not proteins.
Glucose is converted into ethanol by the enzyme present in the yeast:
A
Zymase
B
Urease
C
Invertase
D
Sucrase
View Answer & Propolis Autopsy
Correct Key: Option ADiagnostic Explanation
Concept:
Alcoholic fermentation is a biochemical process in which sugars such as glucose, fructose, and sucrose are converted into cellular energy, producing ethanol and carbon dioxide as metabolic waste.
Yeast naturally contains an enzyme complex called zymase.
Zymase catalyzes the fermentation of simple sugars like glucose into ethanol and carbon dioxide.
Why other options are incorrect:
Invertase catalyzes the hydrolysis of sucrose into fructose and glucose. Urease catalyzes the hydrolysis of urea into carbon dioxide and ammonia. Sucrase is similar to invertase in breaking down sucrose.
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