Name the linkage connecting monosaccharide units in polysaccharides.

NCERT Exemplar · Q23

Q. Name the linkage connecting monosaccharide units in polysaccharides.

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Concept understanding — Biochemical Bonds

Biochemical Bonds: The Glue That Holds Life Together

Imagine you're building with LEGO bricks. Some bricks click together tightly and never come apart unless you really yank them. Others snap together lightly and can be pulled apart with a gentle tug. Some bricks don't even click — they just stick because of static cling or magnetism.

Biochemical bonds are exactly like that. They are the forces that hold atoms together inside the molecules of your body — your DNA, proteins, fats, and carbohydrates. Without these bonds, you'd literally fall apart into a pile of individual atoms.

The Core Idea

Atoms bond because being bonded is more stable (lower energy) than being alone. Think of it like this: a single atom is like a person standing alone in a cold room. Bonding is like huddling together for warmth — you lose some freedom of movement, but you gain stability.

In biochemistry, we care about four main types of bonds. They differ in strength, how they form, and what they do in living systems.

1. Covalent Bonds — The Strong, Permanent LEGO Clicks

This is the strongest bond in biology. Two atoms share electrons — like two people holding the same umbrella. Each atom contributes one or more electrons, and they both "own" the pair.

Key properties:

Very strong (100–400 kJ/mol)
Forms the backbone of all biomolecules
Takes a lot of energy (or enzymes) to break

Where you find it:

The carbon-carbon bonds in your DNA's sugar-phosphate backbone
The peptide bonds linking amino acids into proteins
The bonds within a glucose molecule

Note

A single covalent bond shares 2 electrons. A double bond shares 4. Triple bonds are rare in biology but exist (e.g., in cyanide).

2. Ionic Bonds — The Static Cling of Opposites

Some atoms steal electrons from others. When that happens, one atom becomes positively charged (lost an electron) and the other becomes negatively charged (gained one). Opposite charges attract — that's an ionic bond.

Key properties:

Moderate strength (5–100 kJ/mol in dry conditions)
Very weak in water (because water molecules get in between)
Easily broken by changes in pH or salt concentration

Where you find it:

In salt bridges that help proteins fold into their correct shape
Between the phosphate groups of DNA and positively charged proteins (histones)

Watch out

Ionic bonds are often called "bonds" but in water they behave more like attractions. Don't confuse them with covalent bonds — they're much weaker in biological fluids.

3. Hydrogen Bonds — The Gentle, Reversible Magnets

This is the most important weak bond in biology. A hydrogen atom that's already covalently bonded to an electronegative atom (like oxygen or nitrogen) gets a slight positive charge. It then gets attracted to another electronegative atom nearby.

Think of it like a weak magnet — it holds things together but can be easily undone.

Key properties:

Weak individually (5–30 kJ/mol)
But many together can be very strong
Easily broken by heat or changes in pH
Directional — they only work when atoms are properly aligned

Where you find it:

Between the two strands of DNA (this is what holds the double helix together)
In protein folding (between amino acids in the backbone)
Between water molecules (giving water its unique properties)

Important

Hydrogen bonds are the reason DNA can unzip for replication. If DNA used covalent bonds between strands, it would be impossible to separate without destroying the molecule.

4. Van der Waals Interactions — The Fleeting, Accidental Touches

Even neutral atoms have temporary, uneven distributions of electrons. These create tiny, momentary charges that attract nearby atoms. It's like two people accidentally brushing shoulders in a crowd — brief, weak, but real.

Key properties:

Extremely weak (0.5–5 kJ/mol per interaction)
Only work when atoms are very close (within 0.3–0.4 nm)
Add up significantly when many atoms are packed together

Where you find it:

In the hydrophobic core of proteins (where oily amino acids pack tightly)
Between lipid tails in cell membranes
In enzyme-substrate binding (helps "grip" the substrate)

Putting It All Together: A Biological Example

Consider a protein in your body. It's a long chain of amino acids held together by covalent peptide bonds. That chain then folds into a specific shape. The folding is guided by:

Hydrogen bonds between backbone atoms (forming alpha helices and beta sheets)
Ionic bonds between charged side chains …

Why this formula?

Biochemical Bonds: Why the Key Formulas Hold

Biochemical bonds are the forces that hold atoms together in biomolecules. The key formulas come from electrostatics and quantum mechanics — not from biology itself. Let's break down the why behind the most important ones.

1. Ionic Bond Energy: Coulomb's Law

Formula:

E = \frac{k \cdot q_1 \cdot q_2}{r}

Why it holds:

Opposite charges attract — this is a fundamental law of physics (Coulomb's law).
In a biochemical context, consider a sodium ion ( $\text{Na}^+$ ) and a chloride ion ( $\text{Cl}^-$ ). The energy released when they come together is directly proportional to the product of their charges ( $q_1 q_2$ ) and inversely proportional to the distance ( $r$ ) between them.
The constant $k$ accounts for the medium (water vs. vacuum). In water, the effective force is weaker because water molecules partially shield the charges — this is why ionic bonds in biology are often weaker in aqueous environments.

Key insight: The formula is not arbitrary — it's derived from the inverse-square law of electrostatics, integrated over the distance the charges move toward each other.

2. Covalent Bond Energy: The Morse Potential (Approximation)

Formula (simplified):

E = D_e \left(1 - e^{-a(r - r_0)}\right)^2

Why it holds:

Covalent bonds arise from shared electrons between atoms. The energy is not a simple inverse-square law because electrons are delocalized.
The Morse potential is an empirical formula that captures two key observations:
1. At equilibrium distance ( $r_0$ ): Energy is minimum ( $E = 0$ in this form).
2. If atoms are pulled apart ( $r \to \infty$ ): Energy approaches $D_e$ (the bond dissociation energy).
3. If atoms are pushed too close ( $r \to 0$ ): Energy skyrockets due to Pauli repulsion (electrons can't occupy the same space).
The exponential term $e^{-a(r - r_0)}$ models the rapid drop in attractive force as distance increases — this comes from quantum mechanical overlap of electron clouds.

Key insight: The formula is a curve fit to quantum mechanical calculations, not a first-principles derivation. But it works because it respects the physics: attraction at long range, repulsion at short range, and a stable minimum.

3. Hydrogen Bond Energy: Dipole-Dipole Interaction

Formula (approximate):

E \approx -\frac{2 \mu_1 \mu_2}{4 \pi \epsilon_0 r^3} \cdot \cos\theta

Why it holds:

A hydrogen bond (e.g., between water molecules) is not a true bond — it's a strong dipole-dipole interaction.
The dipole moment ( $\mu$ ) arises because oxygen is more electronegative than hydrogen, creating partial charges ( $\delta^+$ and $\delta^-$ ).
The energy depends on:
- Strength of dipoles ( $\mu_1 \mu_2$ )
- Distance ( $r$ ) — falls off as $1/r^3$ , much faster than ionic bonds ( $1/r$ )
- Orientation ( $\cos\theta$ ) — strongest when dipoles are aligned head-to-tail

Key insight: The $1/r^3$ dependence comes from the derivative of the dipole field. Unlike point charges, dipoles have a field that decays faster — this is why hydrogen bonds are directional and weaker than covalent bonds.

4. Van der Waals Interaction: Lennard-Jones Potential

Formula:

E = 4\epsilon \left[ \left(\frac{\sigma}{r}\right)^{12} - \left(\frac{\sigma}{r}\right)^6 \right]

Why it holds:

Van der Waals forces arise from temporary fluctuations in electron distribution — even nonpolar molecules have instantaneous dipoles. …

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Polysaccharides are built from monosaccharide units joined by glycosidic linkages — specifically, the bond is an O-glycosidic linkage formed between the anomeric carbon of one sugar and a hydroxyl group of another, with the configuration ( $\alpha$ or $\beta$ ) and position (e.g., 1→4, 1→6) determining the polysaccharide's structure and function.

The key to naming this linkage lies in understanding how monosaccharides connect. Each monosaccharide has a reactive anomeric carbon (the carbonyl carbon that becomes chiral upon cyclization). When two monosaccharides join, a water molecule is eliminated — a condensation reaction — between the anomeric carbon of one sugar and a hydroxyl group of another. The resulting bond is an ether linkage, but in carbohydrate chemistry it has a specific name.

The bond is called a glycosidic linkage. More precisely, it is an O-glycosidic linkage because oxygen is the atom bridging the two sugar units. (If nitrogen or sulfur were involved, you'd have N- or S-glycosidic linkages, but those are less common in natural polysaccharides.)
Two details matter for naming: the configuration at the anomeric carbon ( $\alpha$ or $\beta$ ) and the carbon numbers involved. For example, in starch, glucose units are linked by $\alpha$ -(1→4) glycosidic bonds; in cellulose, they are $\beta$ -(1→4) glycosidic bonds. The "1→4" tells you that carbon-1 of the first sugar is bonded to carbon-4 of the next. …

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Here is the breakdown of the common mistakes students make regarding the linkage connecting monosaccharide units in polysaccharides, and how to avoid each.

The Core Concept

The linkage connecting monosaccharide units in polysaccharides is a glycosidic bond (specifically, an O-glycosidic bond).

Common Mistake #1: Naming the wrong type of bond

The Mistake: Students often answer with vague terms like "covalent bond," "ether bond," or "carbon bond." While technically true (a glycosidic bond is a type of covalent ether bond), these are not specific enough for an exam. The examiner wants the precise biochemical term.
Why it happens: Students memorize the definition of a polysaccharide but fail to connect it to the specific chemical linkage formed during a condensation reaction.
How to Avoid:
- Be specific: Always use the term glycosidic bond (or O-glycosidic bond). This is the standard, accepted answer.
- Link the process: Remember that a glycosidic bond is formed when a hydroxyl group ( $-OH$ ) from one monosaccharide reacts with the anomeric carbon of another, releasing a water molecule (condensation/dehydration synthesis). This is not just any bond; it's the result of a specific reaction between sugar molecules.

Common Mistake #2: Forgetting to specify the "O" (O-glycosidic)

The Mistake: Some students write only "glycosidic bond," which is correct, but advanced or very specific questions might expect "O-glycosidic bond." The "O" indicates the bond is formed through an oxygen atom (which is the case for most common polysaccharides like starch, glycogen, and cellulose).
Why it happens: Students learn the term "glycosidic bond" but don't realize there are subtypes (e.g., N-glycosidic bonds in nucleotides).
How to Avoid:
- Know the subtypes: Understand that in polysaccharides, the linkage is always through an oxygen atom. Therefore, O-glycosidic bond is the most precise and technically correct answer.
- Use it as a default: When in doubt for a polysaccharide question, write "O-glycosidic bond." It shows a deeper understanding.

Common Mistake #3: Confusing it with the linkage in other biomolecules

The Mistake: Students mix up the linkage in polysaccharides with the linkage in proteins (peptide bond) or nucleic acids (phosphodiester bond).
Why it happens: All these are polymers formed by condensation reactions, and students often cram all the "bonds" together without clear differentiation.
How to Avoid:
- Create a mental table: For each class of biomolecule, memorize its specific monomer and the specific bond.
  - Polysaccharides: Monosaccharides → Glycosidic bond
  - Proteins: Amino acids → Peptide bond
  - Nucleic Acids: Nucleotides → Phosphodiester bond
- Use mnemonics: For example, "Glycosidic for Glucose (sugars)," "Peptide for Proteins," "Phosphodiester for Polynucleotides." …

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Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

Showing the 12 most recent of 19 on this concept.

TG EAPCET 2026Set eng-2026-05-10-AN1 markMCQ
$\mathrm{AgNO_3}$
›Reveal solutionSolution
Fehling’s test detects reducing sugars using Cu²⁺ in alkaline medium; solution‑B provides the alkali and a complexing agent, which is Rochelle salt (potassium sodium tartrate). The correct option is (B).

Concept & Intuition

Fehling’s test is a classic chemical test for reducing sugars (like glucose). The key is that copper(II) ions (from CuSO₄ in solution‑A) are reduced to brick‑red copper(I) oxide (Cu₂O) by the sugar. But if you simply mix CuSO₄ with a strong base (like NaOH), you get a precipitate of Cu(OH)₂ — not useful for a clear test. To keep the copper ions in solution under alkaline conditions, you need a complexing agent that binds Cu²⁺ and prevents precipitation. That’s the job of the substance in Fehling’s solution‑B.

Step‑by‑step reasoning

Identify the role of solution‑B

Fehling’s solution‑B must provide an alkaline environment (needed for the sugar to act as a reducing agent) and a ligand that keeps Cu²⁺ soluble. Without the ligand, Cu²⁺ would precipitate as Cu(OH)₂.

What common ligands work?

Tartrate ions (from tartaric acid salts) form a deep‑blue soluble complex with Cu²⁺. The specific salt used is potassium sodium tartrate tetrahydrate — known as Rochelle salt. It’s a double salt: KNaC₄H₄O₆·4H₂O.

Check the options

(A) AgNO₃ — silver nitrate; no relation to Fehling’s test.

(B) Rochelle salt — correct; it complexes Cu²⁺ and provides mild alkalinity when mixed with NaOH (which is also in solution‑B).

(C) Sodium hypohalite — used in haloform reactions, not here.

(D) Sodium citrate — used in Benedict’s test (a variant), but Fehling’s specifically uses tartrate.

Confirm the composition …
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TG EAPCET 2026Set eng-2026-05-10-FN1 markMCQ
$\mathrm{H_2N-CH_2-CO-NH-CH(CH_3)-CO-NH-CH(CH_3)-COOH}$
›Reveal solutionSolution

Gly–Ala–Gly must read $\mathrm{CH_2}$ – $\mathrm{CH(CH_3)}$ – $\mathrm{CH_2}$ from the free $-\mathrm{NH_2}$ to the free $-\mathrm{COOH}$ , i.e. exactly one methyl branch, in the middle. That is option (B).

The concept first

Peptide bond. When the $-\mathrm{COOH}$ of one amino acid condenses with the $-\mathrm{NH_2}$ of the next, water is lost and a $-\mathrm{CO\!-\!NH}-$ (amide/peptide) link is formed:
$\mathrm{H_2N\!-\!CHR\!-\!COOH}+\mathrm{H_2N\!-\!CHR'\!-\!COOH}\ \xrightarrow{-\mathrm{H_2O}}\ \mathrm{H_2N\!-\!CHR\!-\!CO\!-\!NH\!-\!CHR'\!-\!COOH}$
A tripeptide therefore has three residues and two peptide bonds.

Reading direction. By universal convention a peptide is named from the N-terminal residue (the one keeping a free $-\mathrm{NH_2}$ ) to the C-terminal residue (the one keeping a free $-\mathrm{COOH}$ ). So "Glycine–Alanine–Glycine" means: glycine at the amino end, alanine in the middle, glycine at the acid end.

The two side chains here.
$\text{Glycine: }\ \mathrm{H_2N\!-\!CH_2\!-\!COOH}\quad(\mathrm{R}=\mathrm{H}\Rightarrow\alpha\text{-carbon shows as }\mathrm{CH_2})$ $\text{Alanine: }\ \mathrm{H_2N\!-\!CH(CH_3)\!-\!COOH}\quad(\mathrm{R}=\mathrm{CH_3})$
Step-by-step

Step 1 — lay out the three residues in order.
$\underset{\text{Gly}}{\mathrm{H_2N\!-\!CH_2\!-\!COOH}}\ \ \underset{\text{Ala}}{\mathrm{H_2N\!-\!CH(CH_3)\!-\!COOH}}\ \ \underset{\text{Gly}}{\mathrm{H_2N\!-\!CH_2\!-\!COOH}}$
Step 2 — form the first peptide bond (Gly $\mathrm{COOH}$ + Ala $\mathrm{NH_2}$ , $-\mathrm{H_2O}$ ):
$\mathrm{H_2N\!-\!CH_2\!-\!CO\!-\!NH\!-\!CH(CH_3)\!-\!COOH}$
Step 3 — form the second peptide bond (Ala $\mathrm{COOH}$ + the second Gly's $\mathrm{NH_2}$ , $-\mathrm{H_2O}$ ):
$\mathrm{H_2N\!-\!CH_2\!-\!CO\!-\!NH\!-\!CH(CH_3)\!-\!CO\!-\!NH\!-\!CH_2\!-\!COOH}$
That is the tripeptide Gly–Ala–Gly. …
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TG EAPCET 2026Set ap-2026-05-05-FN1 markMCQ
$Q. Match the following List-1 List-2 A. Cottrell precipitator I. Antimony colloid B. Kalaazar II. Curd C. Lactobacilli III. Drinking water D. Alum IV. Smoke The correct answer is (A) A - IV, B - II, C - I, D - III (B) A - I, B - IV, C - II, D - III (C) A - IV, B - I, C - III, D - II (D) A - IV, B - I, C - II, D - III$
›Reveal solutionSolution
Match each term with its application in colloid chemistry: Cottrell precipitator removes smoke (IV), Kalaazar is treated with antimony colloid (I), Lactobacilli produce curd (II), and alum purifies drinking water (III). The answer is (D).

This question tests your understanding of practical applications of colloids and related chemical processes. Each item in List-1 represents either a device, a disease, a microorganism, or a chemical that has a specific connection to colloidal systems or their applications.

Let me work through each pairing by examining what each term means and how it relates to colloid chemistry:

Cottrell precipitator → IV (Smoke)

The Cottrell precipitator is an electrostatic device used to remove colloidal particles from industrial smoke. Smoke is a colloidal dispersion of solid particles in air (an aerosol). The precipitator works by charging the smoke particles as they pass through a high-voltage electrode, then attracting them to oppositely charged plates where they coagulate and fall. This is a classic application of coagulation by electrophoresis—smoke particles carry a charge, and the applied electric field neutralizes that charge, causing precipitation.

Kalaazar → I (Antimony colloid)

Kalaazar (visceral leishmaniasis) is a parasitic disease caused by Leishmania protozoa. Historically and even in some modern treatments, colloidal antimony compounds have been used as therapeutic agents. The antimony colloid acts on the parasite, and its colloidal form allows for better distribution and efficacy in the body. This is a medical application of colloids.

Lactobacilli → II (Curd) …
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TG EAPCET 2025Set eng-2025-05-02-FN1 markMCQ
$Q. The structure of which artificial sweetener contains aspartic acid and phenylalanine parts? (A) Saccharin (B) Sucralose (C) Alitame (D) Aspartame$
›Reveal solutionSolution
The key idea is that aspartame is a dipeptide artificial sweetener made from the amino acids aspartic acid and phenylalanine. The correct option is (D).

The question asks which artificial sweetener contains both aspartic acid and phenylalanine as structural components. This is a straightforward recall of the chemical composition of common artificial sweeteners. The key is to recognize that aspartame is a methyl ester of a dipeptide formed from L-aspartic acid and L-phenylalanine. The other options are chemically unrelated: saccharin is a sulfonamide, sucralose is a chlorinated sucrose derivative, and alitame is a dipeptide but uses alanine and aspartic acid, not phenylalanine.

Identify the relevant concept: Artificial sweeteners can be classified by their chemical structure. Aspartame is unique among the listed options because it is a dipeptide (two amino acids linked). The specific amino acids in aspartame are aspartic acid and phenylalanine. This is why people with phenylketonuria (PKU) must avoid it — they cannot metabolize phenylalanine.

Eliminate incorrect options:

(A) Saccharin: This is a sulfonamide derivative (benzoic sulfimide). It contains no amino acid components.

(B) Sucralose: This is a chlorinated derivative of sucrose (table sugar). It contains no amino acids.

(C) Alitame: This is also a dipeptide sweetener, but it is made from L-aspartic acid and D-alanine (plus a terminal amide). It does not contain phenylalanine.

Confirm the correct option: …
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TG EAPCET 2025Set eng-2025-05-03-FN1 markMCQ
$\alpha$
›Reveal solutionSolution
Maltose is a disaccharide made of two glucose units linked α-1,4; the incorrect statement is that one unit is fructose — both are α-D-glucose.

Maltose is a common disaccharide found in germinating grains and is a product of starch digestion. The key to this question is knowing exactly which monosaccharides make up maltose and how they are linked. Many students confuse maltose with sucrose (table sugar), which does contain glucose and fructose. That mix-up is the classic pitfall here.

Let’s break it down step by step.

Identify the monosaccharide units in maltose.

Maltose is formed from two molecules of D-glucose. Specifically, both units are in the α-D-glucopyranose form. There is no fructose involved. This immediately tells us that statement (B) — “One is α-D-glucose and second one is β-D-fructose” — is suspicious.

Check the glycosidic linkage.

In maltose, the two glucose units are joined by an α-1,4-glycosidic linkage. That means the anomeric carbon (C1) of the first glucose is linked to the C4 hydroxyl of the second glucose, and the configuration at C1 is α. Statement (A) correctly describes this.

Determine reducing or non-reducing nature.

A sugar is reducing if it has a free anomeric carbon (i.e., not involved in a glycosidic bond). In maltose, the second glucose unit retains a free anomeric carbon (C1), so it can open to the aldehyde form and reduce Cu²⁺ or Ag⁺. Both glucose units are themselves reducing sugars. So statement (C) is correct.

Evaluate statement (D). …
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TG EAPCET 2025Set eng-2025-05-03-FN1 markMCQ

Q. Match the following List - 1 (Type of colloid): (A) Sol, (B) Foam, (C) Gel, (D) Aerosol List - 2 (Example): (I) Cloud, (II) Whipped cream, (III) Paint, (IV) Butter The correct answer is (A) A - IV, B - I, C - II, D - III (B) A - III, B - II, C - IV, D - I (C) A - III, B - I, C - IV, D - II (D) A - IV, B - II, C - III, D - I

›Reveal solution

Classify each colloid by (dispersed phase, dispersion medium): sol = solid-in-liquid = paint, foam = gas-in-liquid = whipped cream, gel = liquid-in-solid = butter, aerosol = liquid-in-gas = cloud. That is option (B).

The concept first

Every colloid has two parts: the dispersed phase (the finely divided stuff) and the dispersion medium (what it is spread through). The colloid's name is nothing more than a label for that pair, so you never have to memorise examples — you can reconstruct them. The standard table:

Dispersed phase	Medium	Name	Everyday example
Solid	Liquid	Sol	paint, muddy water
Liquid	Liquid	Emulsion	milk
Gas	Liquid	Foam	whipped cream, soap lather
Liquid	Solid	Gel	butter, cheese, jelly
Liquid	Gas	Aerosol	cloud, mist, fog
Solid	Gas	Aerosol (smoke)	smoke, dust

Step-by-step

(A) Sol. By definition a solid dispersed in a liquid. Paint is solid pigment particles suspended in a liquid vehicle → A – III (Paint).
(B) Foam. Gas in a liquid. Whipped cream is air bubbles beaten into liquid cream → B – II (Whipped cream). …

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TG EAPCET 2025Set ap-2025-04-29-AN1 markMCQ
$Q. The hormone ‘X’ increases glucose levels in blood. Low levels of other hormone ‘Y’ causes lethargyness. What are X, Y respectively? (A) Glucagon, thyroxine (B) Insulin, epinephrine (C) Glucagon, estradiol (D) Insulin, thyroxine$
›Reveal solutionSolution
The question tests your knowledge of two hormones with opposite effects on blood glucose and one that controls metabolic rate. X is glucagon (raises blood glucose) and Y is thyroxine (low levels cause lethargy). The correct pair is (A).

The key here is to connect each hormone to its specific function, not just memorise names. Blood glucose regulation involves a classic push-pull between two pancreatic hormones: glucagon and insulin. Glucagon raises blood glucose by signalling the liver to release stored glycogen; insulin lowers it by promoting glucose uptake into cells. So X, which increases glucose, must be glucagon — not insulin.

Now for Y: "lethargyness" (lethargy) means low energy, sluggishness, a slowed-down metabolism. The hormone that sets the body's metabolic rate is thyroxine, released by the thyroid gland. When thyroxine levels are low, the basal metabolic rate drops, leading to fatigue, weight gain, and lethargy. Epinephrine (adrenaline) also raises blood glucose but is a stress hormone, not primarily linked to chronic lethargy. Estradiol is a female sex hormone and doesn't directly cause lethargy when low.

Let's walk through the options:

Option (A): Glucagon, thyroxine — Glucagon raises blood glucose (fits X). Low thyroxine causes lethargy (fits Y). This matches perfectly. …
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TG EAPCET 2025Set ap-2025-04-30-FN1 markMCQ
$\beta$
›Reveal solutionSolution
To identify β-D-glucose units, look for glucose residues with equatorial (downward in Haworth projection) glycosidic bonds at C1. Cellulose and amylopectin contain β-D-glucose and α-D-glucose respectively, while analyzing the structures shows which polysaccharides have the β configuration.

Understanding Glycosidic Linkages and Anomeric Configuration

The key to this problem is recognizing the difference between α and β configurations at the anomeric carbon (C1) of glucose units in polysaccharides.

The anomeric carbon is the carbonyl carbon that becomes a new chiral center when glucose cyclizes. In the β configuration, the hydroxyl group (or glycosidic oxygen) at C1 is equatorial (points down in standard Haworth projection for D-sugars). In the α configuration, it's axial (points up).

Without seeing the actual structures labeled I, II, III, and IV in your question, I need to work from the common polysaccharides typically presented in this context:

Common Saccharides and Their Glucose Units

Let me identify the typical candidates:

Cellulose - Contains β-D-glucose units linked by β(1→4) glycosidic bonds. Every glucose is in the β configuration.

Amylose - Contains α-D-glucose units linked by α(1→4) glycosidic bonds. All glucose units are α.

Amylopectin - Contains α-D-glucose units with α(1→4) bonds in chains and α(1→6) at branch points. All glucose units are α.

Lactose - Contains one β-D-glucose unit (though it's a disaccharide, not a polysaccharide).

Maltose - Contains α-D-glucose units. …
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TG EAPCET 2024Set ap-2024-05-08-FN1 markMCQ
$_2$
›Reveal solutionSolution
The key is to recall the common charge preferences of common sols: metal oxides/hydroxides (like Al₂O₃·xH₂O, TiO₂) are usually positive in acidic medium; metal sulphides (As₂S₃, CdS) and noble metals (gold) are negative; starch, blood, congo red, and methylene blue have known charges. Counting gives 3 positively charged sols, so the correct option is (A).

Concept & Intuition

Colloidal sols acquire charge due to selective adsorption of ions from the dispersion medium. The sign of the charge depends on the nature of the particle and the pH of the medium. For common sols, there are well-known patterns:

Metal oxides and hydroxides (e.g., Al₂O₃·xH₂O, TiO₂) tend to adsorb H⁺ ions in acidic medium, becoming positively charged.

Metal sulphides (e.g., As₂S₃, CdS) adsorb S²⁻ or HS⁻ ions, giving a negative charge.

Noble metals (e.g., gold) adsorb negative ions from the medium, so gold sol is negatively charged.

Starch and blood (haemoglobin) are typically negatively charged.

Congo red (an anionic dye) gives a negative sol.

Methylene blue (a cationic dye) gives a positively charged sol.

Let’s go through each sol in the list.

As₂S₃ sol – Arsenic sulphide sol is prepared by passing H₂S through arsenious oxide solution. The particles adsorb HS⁻ or S²⁻ ions, so it is negatively charged.

Starch sol – Starch is a non-ionic polymer, but in water it acquires a slight negative charge due to adsorption of OH⁻ ions; it is negatively charged.

Al₂O₃·xH₂O sol – Aluminium hydroxide sol is a metal hydroxide. In acidic medium (common during preparation), it adsorbs H⁺ ions, becoming positively charged.

TiO₂ sol – Titanium dioxide is a metal oxide; like Al₂O₃, it adsorbs H⁺ in acidic medium, so it is positively charged.

Gold sol – Gold particles adsorb negative ions (e.g., AuCl₄⁻ or OH⁻), so gold sol is negatively charged.

Congo red sol – Congo red is an anionic dye (sodium salt of benzidine diazo-bis-1-naphthylamine-4-sulphonic acid); its particles are negatively charged. …
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TG EAPCET 2024Set ap-2024-05-07-AN1 markMCQ
$Q. The vitamin that can be stored in the body and whose deficiency results in disease (A) Scurvy (B) Rickets (C) Convulsions (D) Beri beri$
›Reveal solutionSolution
The question asks which vitamin deficiency disease corresponds to a vitamin that can be stored in the body. The only option that is both a deficiency disease and linked to a fat‑soluble (storable) vitamin is rickets, caused by vitamin D deficiency. The correct option is (B).

The key concept here is the classification of vitamins by solubility. Vitamins are divided into two groups: water‑soluble (B‑complex and C) and fat‑soluble (A, D, E, K). Water‑soluble vitamins are not stored in the body in significant amounts—excess is excreted in urine—so deficiencies develop relatively quickly if intake stops. Fat‑soluble vitamins can be stored in the liver and fatty tissues, so deficiencies take longer to appear but can still occur when stores are depleted.

The question asks for a disease caused by deficiency of a vitamin that can be stored. That means we are looking for a fat‑soluble vitamin deficiency. Let’s examine each option:

Scurvy – Caused by deficiency of vitamin C (ascorbic acid). Vitamin C is water‑soluble and not stored. So scurvy does not fit the “storable” condition.

Rickets – Caused by deficiency of vitamin D. Vitamin D is fat‑soluble and stored in the body. This matches.

Convulsions – This is not a specific vitamin deficiency disease; convulsions can be a symptom of many conditions (e.g., vitamin B6 deficiency, but B6 is water‑soluble). The option is vague and not a classic deficiency disease. …
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TG EAPCET 2024Set eng-2024-05-10-FN1 markMCQ
$B_6$
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Pyridoxine is the chemical name for vitamin B₆, so the correct answer is option (A).

The question asks for the vitamin known as pyridoxine. This is a straightforward naming fact from biochemistry and nutrition. Vitamins often have both a letter-number designation (like B₁, B₂, etc.) and a specific chemical name. Pyridoxine is the common name for one of the forms of vitamin B₆.

Recall the B-vitamin naming system.

The B-complex vitamins are a group of water-soluble vitamins, each with a distinct chemical identity. For example:

Vitamin B₁ is thiamine.

Vitamin B₂ is riboflavin.

Vitamin B₃ is niacin.

Vitamin B₆ is pyridoxine (and related compounds like pyridoxal and pyridoxamine).

Vitamin B₁₂ is cobalamin.

Match the name to the option. …
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TG EAPCET 2023Set ap-2023-05-11-AN1 markMCQ
$Q. Which of the following 0.01 molal aqueous solution will have the highest freezing point? (A) Sodium Sulphate (B) Aluminium Sulphate (C) Potassium Chloride (D) Sucrose$
›Reveal solutionSolution
The freezing point of a solution is a colligative property, meaning it depends on the number of solute particles. The solution with the fewest particles will experience the least freezing point depression and thus have the highest freezing point. Sucrose, being a non-electrolyte, produces the fewest particles, resulting in the highest freezing point. The correct option is (D).

The freezing point of a solution is a colligative property. This means that the change in freezing point depends only on the number of solute particles present in the solution, not on their chemical identity. When a non-volatile solute is added to a solvent, the freezing point of the solvent is lowered. This phenomenon is called freezing point depression.

The extent of freezing point depression ( $\Delta T_f$ ) is directly proportional to the molality ( $m$ ) of the solution and the van't Hoff factor ( $i$ ). The van't Hoff factor accounts for the number of particles a solute dissociates into when dissolved in a solvent.
$\Delta T_f = i \cdot K_f \cdot m$
For a given solvent ( $K_f$ is constant) and a given molality ( $m = 0.01 \text{ molal}$ for all options), the freezing point depression $\Delta T_f$ is directly proportional to the van't Hoff factor $i$ .

A larger $\Delta T_f$ means a lower freezing point. Conversely, a smaller $\Delta T_f$ means a higher freezing point (closer to the pure solvent's freezing point).

Therefore, to find the solution with the highest freezing point, we need to identify the solution with the smallest van't Hoff factor ( $i$ ).

Here's how we determine the van't Hoff factor for each given compound:

Sodium Sulphate ( $\text{Na}_2\text{SO}_4$ )

Sodium sulphate is an ionic compound that dissociates in water:

$\text{Na}_2\text{SO}_4(aq) \rightarrow 2\text{Na}^+(aq) + \text{SO}_4^{2-}(aq)$

It produces 2 sodium ions and 1 sulphate ion, for a total of $2 + 1 = 3$ particles.

So, for sodium sulphate, $i = 3$ .

Aluminium Sulphate ( $\text{Al}_2(\text{SO}_4)_3$ )

Aluminium sulphate is also an ionic compound that dissociates in water:

$\text{Al}_2(\text{SO}_4)_3(aq) \rightarrow 2\text{Al}^{3+}(aq) + 3\text{SO}_4^{2-}(aq)$

It produces 2 aluminium ions and 3 sulphate ions, for a total of $2 + 3 = 5$ particles.

So, for aluminium sulphate, $i = 5$ .

Potassium Chloride ( $\text{KCl}$ )

Potassium chloride is an ionic compound that dissociates in water:

$\text{KCl}(aq) \rightarrow \text{K}^+(aq) + \text{Cl}^-(aq)$

It produces 1 potassium ion and 1 chloride ion, for a total of $1 + 1 = 2$ particles.

So, for potassium chloride, $i = 2$ .

Sucrose ( $\text{C}_{12}\text{H}_{22}\text{O}_{11}$ )

Sucrose is a non-electrolyte. It dissolves in water but does not dissociate into ions. Each sucrose molecule remains as one particle.

So, for sucrose, $i = 1$ .

Now, let's compare the van't Hoff factors and the resulting freezing point depression for each 0.01 molal solution:

| Compound | Van't Hoff Factor ( $i$ ) | Effective Molality ( $i \cdot m$ ) | Freezing Point Depression ( $\Delta T_f$ ) | Freezing Point | …
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Q.Name the linkage connecting monosaccharide units in polysaccharides.

Concept understanding — Biochemical Bonds

Biochemical Bonds: The Glue That Holds Life Together

The Core Idea

1. Covalent Bonds — The Strong, Permanent LEGO Clicks

2. Ionic Bonds — The Static Cling of Opposites

3. Hydrogen Bonds — The Gentle, Reversible Magnets

4. Van der Waals Interactions — The Fleeting, Accidental Touches

Putting It All Together: A Biological Example

Why this formula?

Biochemical Bonds: Why the Key Formulas Hold

1. Ionic Bond Energy: Coulomb's Law

2. Covalent Bond Energy: The Morse Potential (Approximation)

3. Hydrogen Bond Energy: Dipole-Dipole Interaction

4. Van der Waals Interaction: Lennard-Jones Potential

Concept: Glycosidic Linkages in Polysaccharides

Method: Identifying the Glycosidic Linkage

Steps:

The Core Concept

Common Mistake #1: Naming the wrong type of bond

Common Mistake #2: Forgetting to specify the "O" (O-glycosidic)

Common Mistake #3: Confusing it with the linkage in other biomolecules

The concept first

Step-by-step

The concept first

Step-by-step

Understanding Glycosidic Linkages and Anomeric Configuration

Common Saccharides and Their Glucose Units

Q.Name the linkage connecting monosaccharide units in polysaccharides.

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