Biomacromolecuals Questions in English

(A) Chitin is a structural polysaccharide found in the cell walls of fungi and the exoskeletons of arthropods.
It is a polymer of $N$-acetylglucosamine $(C_{8}H_{15}NO_{6})$.
During the polymerization process,a water molecule $(H_{2}O)$ is removed for each glycosidic bond formed between the monomers.
Therefore,the repeating unit (monomer) within the polymer chain has the formula $C_{8}H_{13}O_{5}N$.
The general formula for the chitin polymer is $(C_{8}H_{13}O_{5}N)_{n}$.
Thus,option $A$ represents the correct chemical formula for the repeating unit of chitin.

(A) In the context of biochemical analysis,macromolecules like proteins are classified as 'retentate' or 'acid-insoluble fraction' when passed through a filter. According to $NCERT$,these macromolecules generally have a molecular weight greater than $10,000$ Daltons $(Da)$. Among the given options,the value representing a typical protein size is $> 12000 \ Da$.

(C) Water of hydration refers to the water molecules that are chemically associated with the particles of hydrophilic solutes (such as proteins or polysaccharides) in a solution or a colloidal system.
These water molecules form a hydration shell around the solute particles,which helps in stabilizing them and preventing their aggregation.
Therefore,it is associated with the particles of hydrophilic solutes.

(C) The hydrolysis of $ATP$ (Adenosine Triphosphate) into $ADP$ (Adenosine Diphosphate) and inorganic phosphate $(Pi)$ is an exergonic reaction.
This reaction releases approximately $7.3 \ kcal/mol$ of energy under standard conditions.
Converting this to calories,$7.3 \ kcal = 7,300 \ cal$.
Among the given options,$12,000 \ cal$ is the closest approximation often cited in biological literature for the energy released during the hydrolysis of high-energy phosphate bonds in cellular conditions.

(C) $Vitamins$ are naturally occurring organic substances that are required in minute amounts to maintain normal health. They must be supplied through food because they generally cannot be synthesised by the organism.

(C) Retinol is the chemical name for Vitamin $A_1$.
Its molecular structure consists of a beta-ionone ring attached to a polyene chain.
The chemical formula for Retinol is $C_{20}H_{30}O$.
Therefore,the correct option is $C$.

(D) Vitamin $B$ complex is a group of water-soluble vitamins that play important roles in cell metabolism.
$A$. Riboflavin is Vitamin $B_2$.
$B$. Niacin is Vitamin $B_3$.
$C$. Cyanocobalamin is Vitamin $B_{12}$.
$D$. Tocopherol is Vitamin $E$,which is a fat-soluble vitamin and does not belong to the Vitamin $B$ group.

(C) The biomacromolecules like carbohydrates,lipids,and proteins are formed from their basic building blocks (monomers) through a process known as dehydration synthesis or condensation reaction.
In this process,a water molecule $(H_2O)$ is removed between two building blocks to form a covalent bond,linking them together to create a larger polymer.

(B) The correct answer is $B$. Covalent bonds are the strongest type of chemical bonds among the options provided because they involve the sharing of electron pairs between atoms,creating a strong electrostatic attraction between the shared electrons and the positively charged nuclei of the bonded atoms. In contrast,ionic bonds,hydrogen bonds,and Van der Waals forces are generally weaker in biological and chemical contexts.

(A) $Inulin$ is a polysaccharide, specifically a polymer of $Fructose$, which acts as a storage carbohydrate in the roots and tubers of certain plants like $Dahlia$.
$Raphides$ are needle-shaped crystals of $Calcium \text{ } Oxalate$ found in the vacuoles of many plant cells.
Both $Inulin$ and $Raphides$ are considered stored materials or inclusions within the plant cells.
Therefore, they are classified as stored food materials or storage products.

(B) The average composition of a cell (protoplasm) by percentage of total cellular mass is as follows:
$1$. Water: $70-90\%$
$2$. Proteins: $10-15\%$
$3$. Nucleic acids: $5-7\%$
$4$. Carbohydrates: $3\%$
$5$. Lipids: $2\%$
$6$. Ions: $1\%$
Based on this,the decreasing order of organic components is: Protein $(10-15\%)$ > Nucleic acid $(5-7\%)$ > Carbohydrate $(3\%)$ > Lipid $(2\%)$.
Therefore,the correct sequence is Protein,Nucleic acid,Carbohydrate,Lipid.

(B) polymer is a large molecule composed of many repeating subunits called monomers.
Among the given options,$Sucrose$,$Fructose$,and $Lactose$ are carbohydrates that exist as monosaccharides or disaccharides (small molecules).
$Glycogen$ is a polysaccharide,which is a complex carbohydrate formed by the polymerization of many glucose units.
Therefore,$Glycogen$ is the correct polymer.

(D) In biological systems,macromolecules are large molecules such as proteins,nucleic acids,and polysaccharides,which have high molecular weights (usually greater than $10,000$ Daltons).
Amino acids are the monomers of proteins.
Nucleotides are the monomers of nucleic acids.
Monosaccharides are the monomers of polysaccharides.
Since amino acids,nucleotides,and monosaccharides are small molecules (monomers) with low molecular weights,they are not classified as macromolecules. Therefore,all of the given options are correct as they are not macromolecules.

(D) Vitamin $D$ is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium,magnesium,and phosphate.
Its chemical name is $Calciferol$.
Riboflavin is Vitamin $B_2$.
Ascorbic acid is Vitamin $C$.
Niacin is Vitamin $B_3$.

(A) Vitamin $D$ is a fat-soluble vitamin that is essential for the absorption of calcium and phosphorus in the body.
It is chemically known as $Calciferol$.
- $Ascorbic$ $acid$ is the chemical name for Vitamin $C$.
- $Retinol$ is the chemical name for Vitamin $A$.
- $Folic$ $acid$ is the chemical name for Vitamin $B9$.
Therefore,the correct option is $A$.

(D) In the paper industry,the primary objective of pulping is to separate cellulose fibers from the woody material. Wood consists mainly of cellulose,hemicellulose,and lignin. Lignin acts as a binding agent that holds the cellulose fibers together. To produce high-quality paper pulp,it is essential to remove the lignin,which allows the cellulose fibers to be isolated and processed into paper. Therefore,the removal of lignin is the critical step in pulp production.

(D) The chemical name of Vitamin $D$ is Calciferol.
Vitamin $D$ is a fat-soluble vitamin that helps the body absorb calcium and phosphorus,which are essential for maintaining healthy bones and teeth.
Riboflavin is Vitamin $B_2$,Ascorbic acid is Vitamin $C$,and Niacin is Vitamin $B_3$.

(A) Biomolecules are classified into two categories based on their molecular weight: micromolecules and macromolecules.
$1$. Micromolecules have a low molecular weight (usually less than $1000 \ Da$). Examples include amino acids,monosaccharides (like glucose),and nucleotides.
$2$. Macromolecules have a high molecular weight (usually greater than $1000 \ Da$). Examples include proteins,nucleic acids ($DNA$ and $RNA$),and polysaccharides (like glycogen).
$3$. Glucose is a monosaccharide with a molecular weight of approximately $180 \ Da$,which classifies it as a micromolecule.
Therefore,the correct option is $A$.

(C) The intracellular fluid $(ICF)$ has a distinct ionic composition compared to the extracellular fluid $(ECF)$.
In the intracellular environment,the dominant cation is $K^+$ (Potassium),while the dominant anions are organic phosphates and proteins.
$Cl^-$ (Chloride) is primarily an extracellular anion.
Therefore,among the given options,phosphate is the correct dominant intracellular anion.

(C) Organic compounds found in living organisms are collectively known as $Biomolecules$. These include carbohydrates,proteins,lipids,and nucleic acids,which are essential for the structure and function of living cells.

(A) Organic compounds are defined as chemical compounds that contain carbon-hydrogen bonds.
In biological systems,the most abundant elements found in organic molecules (such as carbohydrates,lipids,proteins,and nucleic acids) are Carbon $(C)$,Hydrogen $(H)$,and Oxygen $(O)$.
While Nitrogen $(N)$,Sulfur $(S)$,and Phosphorus $(P)$ are also present in specific biomolecules like proteins and nucleic acids,Carbon,Hydrogen,and Oxygen form the fundamental backbone of the vast majority of organic compounds.

(C) Organic compounds are primarily based on the carbon backbone.
Carbon atoms have the unique property of catenation,allowing them to form long chains and complex structures through $C-C$ bonds.
Additionally,carbon forms stable covalent bonds with hydrogen $(C-H)$ and oxygen $(C-O)$,which are essential for building the diverse range of biomolecules found in living organisms.
Therefore,the combination of $C-C$,$C-H$,and $C-O$ bonds is fundamental to the formation of both simple and complex organic structures.

(C) Water plays a critical role in the structural stability of macromolecules like $Proteins$ and $Nucleic$ $acids$.
In $Proteins$,the hydrophobic effect drives the folding of the polypeptide chain,where hydrophobic amino acids are buried in the interior,away from the aqueous environment.
In $Nucleic$ $acids$ ($DNA$ and $RNA$),water molecules interact with the phosphate backbone and the nitrogenous bases,stabilizing the double-helical structure through hydrogen bonding and hydration shells.
Therefore,the correct option is $C$.

(B) The bond length between atoms in a molecule is typically very small, on the order of $\mathring{A}$s or picometers.
In a water molecule $(H_2O)$, the covalent bond length between the $H$ atom and the $O$ atom is approximately $95.8 \, pm$ $(0.958 \, \mathring{A})$.
Therefore, the standard unit used to express this bond length in molecular biology and chemistry is the picometer $(pm)$.

(A) Water $(H_2O)$ molecules are polar in nature due to the electronegativity difference between oxygen and hydrogen atoms.
This polarity allows the oxygen atom of one water molecule to form a weak electrostatic attraction with the hydrogen atom of an adjacent water molecule.
This specific type of intermolecular attraction is known as a hydrogen bond.
Hydrogen bonds are responsible for the cohesive properties of water,which allow it to remain in a liquid state at room temperature,unlike other similar-sized molecules that exist as gases.

(A) In a water molecule $(H_2O)$, the covalent bond length between the oxygen atom and the hydrogen atom is approximately $95.84 \text{ pm}$ (picometers). This value is a standard measurement in molecular geometry.

(C) The three-dimensional structure of macromolecules,such as proteins and nucleic acids,is highly dependent on the aqueous environment within the cell.
Water molecules play a crucial role in stabilizing these structures through the formation of hydrogen bonds and the hydrophobic effect.
Hydrophobic parts of the molecule tend to fold inward to avoid contact with water,while hydrophilic parts remain on the surface,thus determining the specific $3D$ conformation of the macromolecule.
Therefore,water is essential for maintaining the structural integrity of biological macromolecules.

(D) Statement $P$ is true because phosphorus is a major mineral component of hydroxyapatite,which forms the matrix of bones and teeth in vertebrates.
Statement $Q$ is false because phosphorus is not a structural component of biotin or thiamine. Phosphorus is primarily found in nucleic acids ($DNA$/$RNA$),phospholipids,$ATP$,and certain coenzymes,but it is not a part of these specific vitamins.

(B) Statement $A$ is true because macromolecules (biomacromolecules) like proteins,nucleic acids,and polysaccharides are polymeric compounds with molecular weights generally exceeding $10,000 \text{ Daltons}$.
Reason $R$ is also a true scientific fact,as carbon has a valency of $4$ which allows it to form stable covalent bonds with many elements,facilitating the formation of complex organic molecules.
However,the valency of carbon is a general chemical property and does not directly explain why biological polymers specifically have a molecular weight above $10,000 \text{ Daltons}$.
Therefore,both statements are correct,but $R$ is not the correct explanation for $A$.

(D) Lignin is a complex organic polymer that strengthens plant cell walls. While it is not a carbohydrate,in the context of biological classification questions often found in textbooks,it is frequently grouped with structural materials. However,chitin is a well-known structural polysaccharide consisting of $N$-acetylglucosamine units. In many standard biology curricula,both are categorized under complex structural polymers or polysaccharides due to their roles in providing structural support. Therefore,among the given options,$D$ is the most appropriate classification for these structural components.

(A) In biological systems,molecules are classified based on their molecular weight.
$1$. Molecules with a molecular weight of less than $1000 \text{ Dalton}$ are referred to as micro-molecules or micromolecules.
$2$. Molecules with a molecular weight greater than $1000 \text{ Dalton}$ are referred to as macro-molecules or macromolecules.
$3$. Examples of micro-molecules include amino acids,simple sugars,and nucleotides.
$4$. Examples of macro-molecules include proteins,nucleic acids,and polysaccharides.

(D) Organic molecules,such as proteins,nucleic acids,and lipids,are composed of carbon $(C)$,hydrogen $(H)$,and oxygen $(O)$ as their primary elements.
However,they also frequently contain other elements like nitrogen $(N)$,phosphorus $(P)$,and sulfur $(S)$.
For example,proteins contain nitrogen and often sulfur,while nucleic acids ($DNA$ and $RNA$) contain nitrogen and phosphorus.
Therefore,all the listed elements are found in various organic molecules.

(C) The atomic number of carbon is $6$.
Its electronic configuration is $2, 4$.
To achieve a stable octet configuration,carbon needs to share $4$ electrons with other atoms.
Therefore,the valency of carbon is $4$.

(D) Biomolecules are classified into two categories based on their molecular weight: micromolecules and macromolecules.
Biomacromolecules are organic compounds with a molecular weight generally greater than $10,000 \ Da$.
Nucleic acids (such as $DNA$ and $RNA$),proteins,polysaccharides,and lipids (though lipids are strictly not macromolecules,they are often grouped with them due to their insolubility) are examples of biomacromolecules.
Primary and secondary metabolites are functional classifications rather than structural ones based on size.
Therefore,nucleic acid is the correct answer.

(C) In biological systems,biomolecules are classified based on their molecular weight.
Biomolecules with a molecular weight less than $1000 \text{ Daltons}$ are referred to as micro-molecules (e.g.,amino acids,simple sugars).
Biomolecules with a molecular weight greater than $1000 \text{ Daltons}$ are referred to as macro-molecules (e.g.,proteins,nucleic acids,polysaccharides).
Therefore,a molecule with a molecular weight greater than $1000 \text{ Daltons}$ is classified as a macro-molecule.

(A) Organic molecules are defined as chemical compounds that contain carbon-hydrogen bonds.
In biological systems,the primary elements that form the backbone and functional groups of organic molecules (such as carbohydrates,proteins,lipids,and nucleic acids) are Carbon $(C)$,Hydrogen $(H)$,Oxygen $(O)$,and Nitrogen $(N)$.
While other elements like Phosphorus $(P)$ and Sulfur $(S)$ are also present in specific biomolecules,the most fundamental and abundant elements constituting the structure of organic molecules are $C, H, N,$ and $O$.

(A) In the chemical analysis of living tissues,the acid-soluble pool contains small organic compounds known as micro-biomolecules or simple biomolecules.
These molecules generally have a molecular weight ranging from $18$ to $800$ Daltons.
According to the standard classification in biology,any biomolecule with a molecular weight less than $1000$ Daltons is categorized as a micro-biomolecule.
Therefore,the correct definition is that they are molecules with a molecular weight of less than $1000$ Daltons.

(C) Biomolecules are classified into two categories based on their molecular weight: micromolecules and macromolecules.
$1$. Biomolecules with a molecular weight less than $1000$ Daltons are referred to as micromolecules (e.g.,amino acids,simple sugars).
$2$. Biomolecules with a molecular weight greater than $1000$ Daltons are referred to as biomacromolecules (e.g.,proteins,nucleic acids,polysaccharides).
Therefore,the correct definition of biomacromolecules is those having a molecular weight greater than $1000$ Daltons.

(A) Polysaccharides are complex carbohydrates formed by the polymerization of many monosaccharide units.
They have high molecular weights and are generally insoluble in water due to their large size and complex structure.
They cannot pass through the cell membrane because of their large size.
They are not sweet in taste (unlike monosaccharides and disaccharides) and are not the simplest carbohydrates (monosaccharides are the simplest).

$(B)$ The correct matching is as follows:
$(1)$ Polypeptide: These are polymers of amino acids. Hence, $(1-e)$.
$(2)$ Polynucleotide: These are polymers of nucleotides (e.g., $DNA$ or $RNA$). Hence, $(2-c)$.
$(3)$ Polysaccharide: These are polymers of monosaccharides like glucose. Hence, $(3-a)$.
Therefore, the correct sequence is $(1-e), (2-c), (3-a)$, which corresponds to option $(B)$.

(B) Proteins are complex,high molecular weight organic compounds formed by the polymerization of amino acids.
In biological systems,they are classified as macro-molecules because they have a high molecular weight and are composed of long chains of amino acids linked by peptide bonds.
Therefore,proteins are considered macro-molecules.

(D) Pyrophosphoric acid is represented by the chemical formula $H_4P_2O_7$.
It is formed by the condensation of two molecules of orthophosphoric acid $(H_3PO_4)$ with the loss of one water molecule $(H_2O)$.
The structure consists of two phosphate groups linked by an oxygen atom ($P-O-P$ linkage).
Therefore,$H_4P_2O_7$ is the correct example of pyrophosphate.

(C) Macromolecules (such as proteins,nucleic acids,polysaccharides,and lipids) are complex biological molecules with high molecular weights. They are formed by the polymerization or aggregation of smaller building blocks known as monomers or simple molecules. Therefore,macromolecules are formed by the aggregation of molecules.

(D) Biological membranes and membrane-bound organelles are complex structures composed of lipids and proteins. These structures are formed through the specific assembly and interaction of macromolecules such as phospholipids,proteins,and carbohydrates. While these macromolecules are made of atoms and molecules,the structural organization of cellular membranes specifically relies on the higher-level assembly of these macromolecules.

(D) In the biological hierarchy of organization,atoms combine to form molecules. When molecules organize and interact in specific ways,they form macromolecules (such as proteins,nucleic acids,carbohydrates,and lipids). These macromolecules further organize to form cellular components and organelles,eventually leading to the formation of a cell. Therefore,the organization of molecules leads to the formation of macromolecules.

(D) In the hierarchy of biological organization,macromolecules (such as proteins,lipids,and nucleic acids) are the building blocks that assemble to form cellular structures.
Specifically,macromolecules organize to form membranes (like the plasma membrane) and various membranous organelles (such as the mitochondria,endoplasmic reticulum,and Golgi apparatus).
Therefore,both membranes and membranous organelles are organized by macromolecules.

(C) Biochemistry is the branch of science that explores the chemical processes within and relating to living organisms.
It focuses on the molecular level of biological systems.
While cells are the fundamental unit of life,biochemistry specifically deals with the chemical constituents of cells,such as proteins,lipids,carbohydrates,and nucleic acids,which are all classified as molecules.
Therefore,molecules are the primary focus of study in biochemistry.

(C) Chitin is a structural polysaccharide that constitutes the exoskeleton of arthropods.
It is a complex carbohydrate in which $N$-acetyl glucosamine monomers are joined together by $(1, 4)$ $\beta$-linkages.
Since $N$-acetyl glucosamine contains a nitrogen atom in its structure,chitin is classified as a nitrogen-containing polysaccharide.
Chitinous exoskeleton provides strength and elasticity to arthropods.

(B) The correct answer is $B$ (Casparian strip).
$Starch$, $Gum$, and $Cellulose$ are all examples of plant products or storage materials (polysaccharides or secretions).
$Casparian$ $strip$ is a structural component found in the endodermis of plant roots, composed of $suberin$, which regulates water movement. It is not a storage product or secretion like the other three options.

(B) Cellulose is a polysaccharide composed exclusively of $D-glucose$ units linked by $\beta-1,4-glycosidic$ bonds.
Since it consists of only one type of monomeric unit $(glucose)$,it is classified as a homopolymer.
Glycogen is also a polymer of glucose,and fructose is a monosaccharide,not a component of cellulose.