Carbohydrates Questions in English

(C) pentose sugar is a monosaccharide containing $5$ carbon atoms.
$Ribulose$ is a ketopentose sugar with the chemical formula $C_5H_{10}O_5$.
$Galactose$ is a hexose sugar ($6$ carbons).
$Dihydroxy$ $acetone$ is a triose sugar ($3$ carbons).
$Hexose$ is a general term for a $6$-carbon sugar,not a specific pentose sugar.

(C) Glyceraldehyde is a simple sugar with the chemical formula $C_3H_6O_3$.
It contains $3$ carbon atoms in its structure.
Sugars are classified based on the number of carbon atoms they contain.
$A$ sugar with $3$ carbon atoms is known as a triose sugar.
Therefore,glyceraldehyde is a triose.

(B) Uniform cloth is primarily made of cotton, which is a natural fiber.
Cotton is composed of $90\%$ cellulose, which is a polysaccharide consisting of a linear chain of several hundred to many thousands of $\beta(1 \rightarrow 4)$ linked $D$-glucose units.
Cellulose provides structural support to plant cell walls and is the main component used in the manufacturing of cotton textiles.

(C) In the human body,excess glucose is converted into a complex carbohydrate called $Glycogen$ for storage.
$Glycogen$ is a $polysaccharide$ that serves as the primary form of energy storage in animals,primarily stored in the liver and skeletal muscles.
It can be rapidly broken down back into glucose when the body requires energy.

(C) Carbohydrates are polyhydroxy aldehydes or ketones or substances that yield these on hydrolysis. They include sugars,starch,and glycogen.
$A$. Starch is a polysaccharide (carbohydrate).
$B$. Glycogen is a polysaccharide (carbohydrate).
$C$. Wax is a type of lipid (ester of long-chain fatty acids and long-chain alcohols),not a carbohydrate.
$D$. Glucose is a monosaccharide (carbohydrate).
Therefore,wax is not a carbohydrate.

(D) Cellulose is a polysaccharide composed of glucose units and is the primary structural component of plant cell walls,paper,and cotton fibres.
Inulin is a polymer of fructose,not glucose,and is a fructan (polysaccharide of fructose) found in the roots or tubers of certain plants like Dahlia. Therefore,it is not made up of cellulose.

(C) To identify the monosaccharides,let us analyze each item:
$a$. Glycine: It is an amino acid,not a carbohydrate.
$b$. Cellulose: It is a polysaccharide.
$c$. Glycogen: It is a polysaccharide.
$d$. Ribose: It is a monosaccharide (pentose sugar).
$e$. Galactose: It is a monosaccharide (hexose sugar).
$f$. Lactose: It is a disaccharide.
$g$. Maltose: It is a disaccharide.
Therefore,the monosaccharides in the list are Ribose $(d)$ and Galactose $(e)$.
The total count of monosaccharides is $2$.

(D) $1$. $Alanine$ and $Glycine$ are amino acids,which are the building blocks of proteins.
$2$. $Lecithin$ is a phospholipid,which is a type of lipid.
$3$. $Inulin$ is a polymer of fructose,which is a polysaccharide and therefore a carbohydrate.
$4$. Thus,$Inulin$ is the correct answer.

(C) Carbohydrates are the most abundant biomolecules on Earth. They are primarily produced through the process of photosynthesis.
Photosynthesis is carried out by organisms that possess chlorophyll or similar pigments,such as green plants,algae,and certain photosynthetic bacteria (like cyanobacteria).
Fungi and viruses do not perform photosynthesis and therefore do not produce carbohydrates in this manner.
Thus,the correct group consists of some bacteria (photosynthetic),algae,and green plant cells.

(B) Glycogen is a polysaccharide that serves as the primary form of energy storage in animals and fungi.
It is a branched polymer composed of repeating units of $D-glucose$ linked by $\alpha-1,4-glycosidic$ bonds in the linear chains and $\alpha-1,6-glycosidic$ bonds at the branching points.
Therefore,the correct answer is $Glucose$.

(D) Glycogen is a multi-branched polysaccharide of glucose that serves as a form of energy storage in animals,fungi,and bacteria. In humans,it is primarily synthesized and stored in the liver and muscle cells. When the body requires energy,the liver breaks down glycogen into glucose and releases it into the bloodstream. Lactose,galactose,and arabinose are not polysaccharides stored in the liver.

(A) Polysaccharides are complex carbohydrates formed by the polymerization of many monosaccharide units.
$1$. Starch is a storage polysaccharide in plants.
$2$. Glycogen is a storage polysaccharide in animals.
$3$. Cellulose is a structural polysaccharide found in plant cell walls.
Sucrose,maltose,and lactose are disaccharides,while glucose,fructose,and galactose are monosaccharides.
Therefore,the correct group is Starch,Glycogen,and Cellulose.

(C) Cellulose is a polysaccharide consisting of a linear,unbranched chain of several hundred to many thousands of $\beta-D$-glucose units.
These glucose units are linked together by $\beta-1, 4$-glycosidic bonds.
Unlike starch (which contains $\alpha$-linkages),the $\beta$-linkages in cellulose result in a straight,rigid,and fibrous structure that provides structural support to plant cell walls.

(D) Lactose is a disaccharide sugar that is commonly found in milk.
It is formed by the condensation reaction between two monosaccharide units.
The two monosaccharide units that make up lactose are $Glucose$ and $Galactose$.
These are linked together by a $\beta-1,4-glycosidic$ bond.
Therefore,the correct option is $D$.

(A) Inulin is a polysaccharide,specifically a fructan,which is stored in the roots or tubers of certain plants like Dahlia as a reserve food material. Pectin is a structural polysaccharide found in the primary cell walls of terrestrial plants. Both are considered stored substances or reserve materials in the context of plant physiology.

(B) Cellulose is a polysaccharide consisting of a linear chain of several hundred to many thousands of $\beta(1\rightarrow4)$ linked $D$-glucose units.
It is the structural component of the primary cell wall of green plants,many forms of algae,and the oomycetes.
Because it is the main component of plant cell walls,which make up the vast majority of biomass on Earth,cellulose is considered the most abundant organic compound in the biosphere.

(B) Chitin is a complex structural polysaccharide found in the exoskeleton of arthropods and the cell walls of fungi.
Chemically,it is a polymer of $N$-acetylglucosamine,which is a derivative of glucose.
Because it contains an amino group (specifically an acetylated amino group) in its monomeric units,it is classified as a nitrogen-containing polysaccharide.

(B) non-reducing sugar is a carbohydrate that cannot act as a reducing agent because it lacks a free aldehyde or ketone group.
In disaccharides like maltose and lactose,the glycosidic bond involves the anomeric carbon of one sugar,but the other sugar still has a free anomeric carbon,making them reducing sugars.
In sucrose,the glycosidic bond is formed between the anomeric carbons of both glucose and fructose ($C_1$ of glucose and $C_2$ of fructose).
Since both anomeric carbons are involved in the bond,there is no free aldehyde or ketone group available,making sucrose a non-reducing sugar.

(D) Chitin is a structural polysaccharide found in the exoskeleton of arthropods and the cell walls of fungi. It is a linear polymer consisting of $N$-acetylglucosamine (a derivative of glucose) units linked by $\beta-(1,4)$-glycosidic bonds. Therefore,it is a polymer of $N$-acetylglucosamine.

(B) Starch is an ideal storage polysaccharide in plants due to the following reasons:
$1$. It is chemically non-reactive,which prevents it from interfering with the metabolic processes of the cell.
$2$. It is osmotically inactive because it is a large,insoluble molecule. This prevents it from affecting the water potential of the cell,unlike simple sugars like glucose.
Therefore,properties $(b)$ and $(d)$ make starch an efficient storage material.

(A) Sugars (carbohydrates) are polyhydroxy aldehydes or polyhydroxy ketones.
This means they contain multiple hydroxyl $(-OH)$ groups and a single carbonyl $(C=O)$ group (either an aldehyde or a ketone group).
Therefore,the two functional groups characteristic of sugars are carbonyl and hydroxyl.

(C) Lactose,also known as milk sugar,is found exclusively in milk and contains a $\beta-1,4$ glycosidic linkage.
It is a disaccharide formed by the condensation reaction between a molecule of galactose and a molecule of glucose.

(C) Starch is the reserve food material in plant cells,whereas cellulose is the most important structural component of the cell wall of plants.
Both starch and cellulose are polymers of glucose.
Starch is a branched polymer of $\alpha-D$-glucose units linked by $\alpha-1,4$-glycosidic bonds (and $\alpha-1,6$-glycosidic bonds at branching points).
Cellulose is a linear polymer of $\beta-D$-glucose units connected through $\beta-1,4$-glycosidic bonds.
Unlike starch,cellulose is insoluble in ordinary solvents and does not give any colour with iodine.

(B) carbohydrate is considered non-reducing if it lacks a free aldehyde or ketone group capable of acting as a reducing agent.
In $Sucrose$,the glycosidic linkage is formed between the $C1$ of glucose and the $C2$ of fructose.
Since both the anomeric carbons are involved in the glycosidic bond,there is no free aldehyde or keto group available.
Therefore,$Sucrose$ is a non-reducing sugar,whereas $Maltose$,$Lactose$,and $Ribose$ $5$-phosphate contain free anomeric carbons and are reducing sugars.

(A) glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group,which may or may not be another carbohydrate.
These bonds are formed by a dehydration reaction (also known as a condensation reaction),where a water molecule is removed during the linkage of two monosaccharides.
In polysaccharides,individual monosaccharides are linked by these glycosidic bonds to form long chains.
Since the formation of the bond involves the process of dehydration,the Reason correctly explains the Assertion.

(N/A) Ball and stick models are $3-D$ molecular models that can be used to describe the structure of biomolecules.
In a ball and stick model,the atoms are represented as balls,whereas the bonds that hold the atoms together are represented by sticks. Double and triple bonds are represented by springs that form curved connections between the balls. The size and color of various atoms are different and are depicted by the relative size and color of the balls.
It is the most fundamental and common model for representing biomolecular structures.
In the provided ball and stick model of $D$-glucose,the oxygen atoms are represented by red balls,hydrogen atoms by blue balls,while carbon atoms are represented by grey balls.

(N/A) Gums are hetero-polysaccharides. They are composed of two or more different types of monosaccharides.
On the other hand,Fevicol is a synthetic adhesive made of polyvinyl alcohol $(PVA)$. It is a polymer,but it is not a polysaccharide.

(N/A) Approximately $100$ billion tonnes of cellulose are produced annually by all plants in the biosphere. It is estimated that it takes approximately $17$ full-grown trees to manufacture one ton of paper. Trees are also extensively used to fulfill other human requirements such as timber,food,medicines,and fuel. Due to these diverse and widespread uses,it is difficult to calculate the exact annual consumption of plant material by man,but it represents a significant loss of vegetation.

(N/A) $\rightarrow$ The acid-insoluble pellet also contains polysaccharides (carbohydrates) as another class of macromolecules.
$\rightarrow$ Polysaccharides are long chains of sugars. They are threads (literally a cotton thread) containing different monosaccharides as building blocks.
$\rightarrow$ Cellulose is a polymeric polysaccharide consisting of only one type of monosaccharide, i.e., glucose. Cellulose is a homopolymer.
$\rightarrow$ Starch is a variant of cellulose but is present as a storehouse of energy in plant tissues.
$\rightarrow$ Animals have another polysaccharide called glycogen.
$\rightarrow$ Inulin is a polymer of fructose.
$\rightarrow$ In a polysaccharide chain (e.g., glycogen), the right end is called the reducing end, and the left end is called the non-reducing end.
$\rightarrow$ Starch forms helical secondary structures. Starch can hold $I_2$ molecules in the helical portion. The starch-$I_2$ complex is blue in colour.
$\rightarrow$ Cellulose does not contain complex helices and hence cannot hold $I_2$.
$\rightarrow$ Plant cell walls are made of cellulose. Paper made from plant pulp and cotton fibre is cellulosic.
$\rightarrow$ There are more complex polysaccharides in nature. They have amino-sugars and chemically modified sugars (e.g., glucosamine, $N$-acetyl galactosamine, etc.) as building blocks.
$\rightarrow$ Exoskeletons of arthropods have a complex polysaccharide called chitin. These complex polysaccharides are heteropolymers.

(N/A) $(i)$ $A$ glycosidic bond is a type of covalent bond that joins a carbohydrate (sugar) molecule to another group,which may or may not be another carbohydrate. It is formed by a dehydration synthesis reaction between two monosaccharides,where a water molecule is removed.
$(ii)$ $A$ phosphodiester bond occurs in nucleic acids ($DNA$ and $RNA$). It links the $3'$ carbon atom of one sugar molecule to the $5'$ carbon atom of the sugar molecule of the succeeding nucleotide via a phosphate group. Since there is an ester bond on both sides of the phosphate group,it is termed a phosphodiester bond.

(B) In proteins,amino acids are linked together by peptide bonds.
Similarly,in polysaccharides,individual monosaccharide units are linked together by glycosidic bonds.
Therefore,the correct answer is the glycosidic bond.

(A) Starch is a polysaccharide composed of amylose and amylopectin.
When iodine solution ($I_2$ in $KI$) is added to starch,the iodine molecules get trapped within the helical structure of the amylose component.
This complex formation results in a characteristic deep blue-black color.
Therefore,the correct color produced is blue-black.

(A) Cotton fibre consists of cellulose,which is a structural polysaccharide found in plant cell walls.
$(b)$ The exoskeleton of a cockroach is composed of chitin,a nitrogen-containing polysaccharide.
$(c)$ Liver stores glucose in the form of glycogen,which is known as animal starch.
$(d)$ Peeled potato is a rich source of starch,which is the primary storage polysaccharide in plants.

(A) $(1)$ The formula $C_6H_{12}O_6$ represents Glucose,which is a simple sugar and the primary substrate for cellular respiration.
$(2)$ The formula $C_2H_5OH$ represents Ethanol,which is a product of alcoholic fermentation in yeast.

(D) Micronutrients are nutrients required by the body in small quantities,including vitamins and minerals (e.g.,Iron,Iodine).
Glucose is a simple sugar and a carbohydrate,which is classified as a macronutrient because the body requires it in large amounts to provide energy.
Therefore,Glucose is not a micronutrient.

(A) Amylopectin is a major component of starch,which is a branched-chain polysaccharide.
It consists of a long chain of glucose units linked by $\alpha-1,4$ glycosidic bonds,with branches occurring at intervals due to $\alpha-1,6$ glycosidic bonds.
Due to its highly branched and complex structure,amylopectin is insoluble in water.
Therefore,the correct description is that it is insoluble in $H_{2}O$ and contains both $\alpha-1,4$ and $\alpha-1,6$ glycosidic bonds.

(A) Benedict's solution is a chemical reagent used to test for the presence of reducing sugars like glucose.
When glucose reacts with Benedict's solution,it reduces the copper$(II)$ ions $(Cu^{2+})$ to copper$(I)$ oxide $(Cu_2O)$.
The color of the precipitate depends on the concentration of the reducing sugar present.
- $A$ green precipitate indicates a low concentration of reducing sugar.
- $A$ yellow to orange precipitate indicates a moderate concentration.
- $A$ brick-red precipitate indicates a high concentration of reducing sugar.
- $A$ violet precipitate is not formed in this reaction; it is characteristic of the Biuret test for proteins.

(A) Sucrose is a disaccharide composed of two monosaccharides: glucose and fructose.
In sucrose,the glycosidic bond is formed between the $C-1$ of $\alpha$-$D$-glucose and the $C-2$ of $\beta$-$D$-fructose.
This specific linkage is known as an $\alpha, \beta-1,2$-glycosidic linkage.

(A) Iodine test is a common chemical test used to detect the presence of starch,which is a polysaccharide. When iodine solution ($I_2$ in $KI$) is added to a sample containing starch,it forms a blue-black complex. This test is specific for starch and helps differentiate it from monosaccharides,disaccharides,and other non-starchy polysaccharides.

(C) Chitin is a complex carbohydrate known as a polysaccharide. It is a polymer of $N$-acetylglucosamine units linked by $\beta-1,4$-glycosidic bonds. It serves as a structural component in the cell walls of fungi and the exoskeletons of arthropods.

(D) Lactose is a disaccharide composed of two monosaccharide units: galactose and glucose.
Upon hydrolysis,the glycosidic bond between these two units is broken,resulting in one molecule of galactose and one molecule of glucose.

(D) Glycogen is a polysaccharide that acts as the storage form of glucose in animals.
Upon complete hydrolysis,glycogen breaks down into its monomeric units,which are glucose molecules.

(B) This is the Molisch test,which is a sensitive chemical test for the presence of carbohydrates.
In this procedure,the carbohydrate solution is mixed with an alcoholic solution of $\alpha$-naphthol.
Then,concentrated $H_{2}SO_{4}$ is added slowly along the sides of the test tube.
The concentrated acid dehydrates the carbohydrates to form furfural or its derivatives.
These derivatives react with $\alpha$-naphthol to produce a purple or violet-coloured ring at the junction of the two liquid layers.

(C) Fructose is a naturally occurring monosaccharide found in many fruits and is known as fruit sugar.
It is the sweetest among all naturally occurring carbohydrates.
Its sweetness is approximately $1.7$ times that of sucrose (table sugar).

(D) Cellulose is a polysaccharide consisting of a linear chain of several hundred to many thousands of $\beta(1 \rightarrow 4)$ linked $D$-glucose units. It is the structural component of the primary cell wall of green plants,many forms of algae,and the oomycetes. Because it is the main structural component of all plant cell walls,it is the most abundant organic compound on Earth,synthesized by nature on the largest scale.

(B) Cellulose is a complex polysaccharide composed of a long chain of $\beta$-glucose units linked by $\beta-1,4$-glycosidic bonds.
Due to its high molecular weight and the extensive hydrogen bonding between its chains,it forms a rigid,fibrous structure that is insoluble in water.
In contrast,glucose,fructose,and sucrose are simple sugars (monosaccharides or disaccharides) that are highly soluble in water.

(A) Cellulose,starch,and glycogen are all complex carbohydrates known as polysaccharides.
These are polymers composed of repeating units of the monosaccharide $D-glucose$.
Therefore,they all share the same fundamental monosaccharide unit,which is glucose.

(D) Glycogen is a complex carbohydrate known as a polysaccharide.
It is a branched polymer composed of many glucose monomeric units linked together.
It serves as the primary storage form of glucose in animals and fungi.

(A) Glucose is a monosaccharide,not a disaccharide. Therefore,statement $A$ is false.
Starch is a complex carbohydrate known as a polysaccharide.
Glucose and fructose are structural isomers,not anomers.
Invert sugar is an equimolar mixture of glucose and fructose obtained by the hydrolysis of sucrose.