Nucleic acids Questions in English

(A) The Feulgen reaction is a staining technique used in histology to identify chromosomal material or $DNA$ in cell specimens.
It relies on the acid hydrolysis of $DNA$,which exposes aldehyde groups that then react with Schiff's reagent to produce a magenta color.
Since $RNA$ does not contain deoxyribose,it does not undergo this specific reaction,making the Feulgen reaction specific for $DNA$.

(B) In a typical animal cell,the chemical composition by percentage of total cellular mass is as follows:
Water: $70-90\%$
Proteins: $10-15\%$
Nucleic acids: $5-7\%$
Carbohydrates: $3\%$
Lipids: $2\%$
Ions: $1\%$
Therefore,the percentage of nucleic acids in an animal cell is approximately $5\%$.

(C) $DNA$ stands for Deoxyribonucleic acid.
It is a long chain molecule (polymer) made up of repeating units called nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (deoxyribose),and a phosphate group.
Therefore,$DNA$ is a polymer of nucleotides.

(B) Toluidine blue is a basic thiazine metachromatic dye. It is widely used in histology and cytology to stain acidic components of the cell. It has a high affinity for nucleic acids,specifically $RNA$,which it stains purple or blue due to its metachromatic properties. While it can interact with $DNA$,its primary and most distinct staining application in biological tissues is for $RNA$ and acidic polysaccharides.

(C) The structure of $RNA$ and other macromolecules like $DNA$ and proteins can be studied using $X$-ray crystallography. This technique involves directing $X$-rays at a crystallized sample and analyzing the diffraction pattern to determine the atomic and molecular structure. Feulgen stain is used for $DNA$ detection,while Toluidine blue is a general histological stain. Chromatography is used for separation of mixtures.

(C) In biological systems,$DNA$ (Deoxyribonucleic acid) molecules are considered the largest macromolecules.
While proteins can be very large,a single $DNA$ molecule,especially in eukaryotic chromosomes,can consist of millions of base pairs,resulting in a molecular weight significantly higher than that of most proteins or $RNA$ molecules.

(C) Phosphorus is a vital element in biological systems. It is a key component of nucleic acids ($DNA$ and $RNA$),which are polymers of nucleotides,known as polynucleotides. Phosphorus is present in the sugar-phosphate backbone of these molecules. Carbohydrates,starch,and fats primarily consist of carbon,hydrogen,and oxygen,and do not contain phosphorus as a structural component.

(B) $1$. Nucleic acids ($DNA$ and $RNA$) are polymers of nucleotides.
$2$. Each nucleotide consists of a nitrogenous base,a pentose sugar,and a phosphate group.
$3$. Nitrogenous bases (purines and pyrimidines) contain nitrogen,which is essential for their synthesis.
$4$. The phosphate group (derived from phosphoric acid) links the nucleotides together in the backbone of the nucleic acid chain.
$5$. Therefore,both nitrogen and phosphorus are essential components of nucleic acids.
$6$. Hence,both statements $P$ and $Q$ are true.

(C) The sugar present in $DNA$ $(Deoxyribonucleic acid)$ is $2-deoxy-D-ribose$.
This sugar contains $5$ carbon atoms,making it a pentose sugar.
Structurally,it contains an aldehyde group at the $C-1$ position,classifying it as an aldose sugar.
Therefore,the sugar in $DNA$ is an aldose pentose.

(B) $RNA$ stands for Ribonucleic Acid.
It is a polymer of nucleotides.
Each nucleotide consists of a nitrogenous base,a phosphate group,and a pentose sugar.
The pentose sugar present in $RNA$ is Ribose sugar.
In contrast,$DNA$ contains Deoxyribose sugar.

(C) Nucleic acids are polymers of nucleotides. Each nucleotide consists of a nitrogenous base,a pentose sugar,and a phosphate group.
In $RNA$ (Ribonucleic acid),the pentose sugar present is Ribose.
In $DNA$ (Deoxyribonucleic acid),the pentose sugar present is Deoxyribose.
Therefore,the structural components (pentose sugars) for $RNA$ and $DNA$ are Ribose and Deoxyribose respectively.

(C) $ATP$ stands for Adenosine Triphosphate.
It is a nucleotide derivative consisting of an adenine base,a ribose sugar,and three phosphate groups.
The sugar present in $ATP$ is ribose,which is a pentose sugar.
$A$ pentose sugar contains $5$ carbon atoms in its structure.
Therefore,the correct answer is $5$.

(C) Statement $C$ is correct. $DNA$ (Deoxyribonucleic acid) contains deoxyribose sugar as its pentose sugar component,which distinguishes it from $RNA$ (Ribonucleic acid) that contains ribose sugar.
Option $A$ is incorrect because cholesterol is a lipid found in cell membranes and blood,not specifically deposited in the subcutaneous layer as a primary storage site.
Option $B$ is incorrect because the outer covering of plant cells is the cell wall (composed of cellulose),while wax (cutin/suberin) forms the cuticle layer.
Option $D$ is incorrect because non-myelinated nerve fibers,by definition,lack a myelin sheath.

(B) The genetic information that dictates the primary structure (amino acid sequence) of proteins is stored in $DNA$ (Deoxyribonucleic acid),which is a type of nucleic acid.
$DNA$ contains the instructions for synthesizing proteins through the processes of transcription and translation.
Therefore,nucleic acids are the molecules responsible for storing the information required for protein structure.

(D) Nucleic acids ($DNA$ and $RNA$) are the macromolecules that store and transmit genetic information.
Because the sequence of nucleotides in $DNA$ determines the specific sequence of amino acids in proteins,$DNA$ requires a vast amount of specific information for its synthesis.
This precise arrangement of nucleotides allows for the immense diversity observed in living organisms.

(D) The information for the synthesis of various proteins is stored in the form of genetic code within the $DNA$ (Deoxyribonucleic acid),which is a type of nucleic acid. $DNA$ contains the instructions required for the cell to function and synthesize proteins. Through the process of transcription,$DNA$ is copied into $mRNA$,which then directs protein synthesis at the ribosomes.

(A) Nucleic acids,such as $DNA$ and $RNA$,are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar,and a phosphate group.
The chemical composition of these components involves the elements Carbon $(C)$,Hydrogen $(H)$,Oxygen $(O)$,Nitrogen $(N)$,and Phosphorus $(P)$.
Therefore,the correct combination of elements present in nucleic acids is $C, H, O, N$ and $P$.

(C) $ATP$ stands for Adenosine Triphosphate.
It consists of a nitrogenous base (adenine),a pentose sugar (ribose),and three phosphate groups.
$A$ molecule consisting of a nitrogenous base,a pentose sugar,and at least one phosphate group is defined as a nucleotide.
Therefore,$ATP$ is a nucleotide.

(C) In a nucleic acid,nucleotides are linked together to form a polynucleotide chain.
This linkage occurs between the $3'$-carbon atom of the sugar molecule of one nucleotide and the $5'$-carbon atom of the sugar molecule of the adjacent nucleotide.
The phosphate group connects these two sugars through two ester bonds,one with each sugar.
This specific linkage is known as a $3'-5'$ phosphodiester bond.

(A) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar.
When a phosphate group is attached to the nucleoside,it forms a nucleotide.
Therefore,a phosphate group is absent in a nucleoside.

(C) $RNA$ stands for Ribonucleic Acid.
It is a polymer of nucleotides.
Each nucleotide consists of a nitrogenous base,a phosphate group,and a sugar molecule.
The sugar present in $RNA$ is a $5$-carbon sugar known as Ribose,which is a pentose sugar.
Therefore,$RNA$ contains ribose type of pentose sugar.

(C) Nucleic acids,such as $DNA$ and $RNA$,are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar,and a phosphate group.
The chemical composition of nucleic acids includes carbon $(C)$,hydrogen $(H)$,nitrogen $(N)$,oxygen $(O)$,and phosphorus $(P)$.
Therefore,besides $C, H, N$ and $O$,phosphorus $(P)$ is present in the structure of nucleic acids.

(D) Nucleic acids are long-chain polymers of nucleotides. The two main types of nucleic acids found in living organisms are $DNA$ (Deoxyribonucleic acid) and $RNA$ (Ribonucleic acid).
$mRNA$ (messenger $RNA$) is a specific type of $RNA$ involved in protein synthesis.
Since $DNA$,$RNA$,and $mRNA$ are all forms of nucleic acids,the correct answer is 'All of the options'.

(B) Nucleic acids,such as $DNA$ and $RNA$,are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
Nucleosides consist only of a nitrogenous base and a pentose sugar,lacking the phosphate group.
Therefore,the fundamental structural unit (monomer) of nucleic acids is the nucleotide.

(B) nucleotide consists of three components: a nitrogenous base,a phosphate group,and a sugar molecule.
In nucleic acids like $DNA$ and $RNA$,the sugar molecule is a $5$-carbon sugar,which is known as a pentose sugar.
Specifically,$DNA$ contains $2$-deoxyribose,while $RNA$ contains ribose,both of which are pentose sugars.

(C) nucleotide consists of three main components: a nitrogenous base (purine or pyrimidine),a pentose sugar (ribose or deoxyribose),and a phosphate group (phosphoric acid).
Fructose is a hexose sugar $(C_6H_{12}O_6)$ and is not a component of nucleotides.
Therefore,fructose is not a subunit of a nucleotide.

(A) Nucleic acids are polymers of nucleotides. $A$ nucleotide consists of three components: a nitrogenous base,a pentose sugar,and a phosphate group.
Nitrogenous bases are classified into two types: Purines (Adenine and Guanine) and Pyrimidines (Cytosine,Thymine,and Uracil).
Sucrose is a disaccharide (carbohydrate),$RNA$ is a nucleic acid,and phosphoric acid is the phosphate component of a nucleotide.
Therefore,Purine is the correct example of a nitrogenous base.

(C) $RNA$ stands for Ribonucleic Acid.
It is a polymer of nucleotides.
Each nucleotide consists of a nitrogenous base,a phosphate group,and a pentose sugar.
The pentose sugar present in $RNA$ is Ribose sugar,which has a hydroxyl group $(-OH)$ at the $2'$ carbon position.
In contrast,$DNA$ contains Deoxyribose sugar,which lacks an oxygen atom at the $2'$ position.

(D) Nitrogenous bases in nucleic acids are classified into two types: purines and pyrimidines.
Purines are double-ring structures,which include Adenine $(A)$ and Guanine $(G)$.
Pyrimidines are single-ring structures,which include Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$.
Therefore,Adenine is a purine.

(B) Nitrogenous bases are classified into two types: purines and pyrimidines.
Purines are double-ring structures consisting of a six-membered pyrimidine ring fused to a five-membered imidazole ring.
Examples of purines include adenine $(A)$ and guanine $(G)$.
In contrast,pyrimidines are single-ring structures.
Therefore,a purine nitrogenous base contains two rings.

(A) Nitrogenous bases are classified into two types: purines and pyrimidines.
Purines (adenine and guanine) are double-ring structures.
Pyrimidines (cytosine,thymine,and uracil) are single-ring structures.
Therefore,a pyrimidine nitrogenous base contains only one ring.

(B) nucleoside is a biochemical compound consisting of a nitrogenous base (either a purine or a pyrimidine) covalently bonded to a pentose sugar (ribose or deoxyribose).
When a phosphate group is added to a nucleoside,it forms a nucleotide.
Therefore,the correct composition of a nucleoside is a nitrogenous base attached to a pentose sugar.

(C) $Nucleoside$ is formed when a nitrogenous base (purine or pyrimidine) is linked to a pentose sugar (ribose or deoxyribose) through an $N-glycosidic$ linkage.
When a phosphate group is added to a nucleoside,it forms a $Nucleotide$.
Nucleic acids are polymers of nucleotides.

(A) nucleoside is formed when a nitrogenous base is attached to a pentose sugar via an $N$-glycosidic linkage.
When the pentose sugar is ribose,the resulting molecule is called a ribonucleoside.
If the sugar were deoxyribose,it would be called a deoxyribonucleoside.
$A$ nucleotide is formed when a phosphate group is also attached to the nucleoside.

(B) nucleoside is formed when a nitrogenous base is attached to a pentose sugar.
When the pentose sugar is deoxyribose,the resulting molecule is called a deoxyribonucleoside.
If a phosphate group is added to this deoxyribonucleoside,it becomes a deoxyribonucleotide.

(B) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar.
When a phosphate group is attached to the $5'$-$OH$ of a nucleoside,it forms a nucleotide.
Therefore,the combination of a nucleoside and a phosphate group is known as a nucleotide.

(D) nucleotide is the basic structural unit of nucleic acids ($DNA$ and $RNA$).
It consists of three components:
$1$. $A$ nitrogenous base (purine or pyrimidine).
$2$. $A$ pentose sugar (ribose or deoxyribose).
$3$. $A$ phosphate group.
When a nitrogenous base is linked to a sugar,it is called a nucleoside. When a phosphate group is added to a nucleoside,it becomes a nucleotide.

(B) nucleoside consists of a nitrogenous base attached to a pentose sugar.
When a phosphate group is added to a nucleoside,it forms a nucleotide.
Specifically,when a ribonucleoside (which contains ribose sugar) combines with a phosphate group,it forms a ribonucleotide.

(C) $ATP$ stands for Adenosine Triphosphate.
It is a complex organic chemical that provides energy to drive many processes in living cells,such as muscle contraction,nerve impulse propagation,and chemical synthesis.
Because it stores and releases energy as needed,it is universally referred to as the energy currency of the cell.

(B) nucleotide is the basic building block of nucleic acids,consisting of a nitrogenous base,a pentose sugar,and a phosphate group.
When many nucleotide units are linked together through phosphodiester bonds,they form a long chain known as a $Polynucleotide$.
Nucleic acids like $DNA$ and $RNA$ are essentially long polymers of nucleotides,i.e.,polynucleotides.

(C) $S$ - Statement: $RNA$ (Ribonucleic acid) contains ribose sugar,which is a $5$-carbon (pentose) sugar. This statement is correct.
$R$ - Reason: $DNA$ (Deoxyribonucleic acid) contains $2$-deoxyribose sugar,not ribulose. Ribulose is a ketopentose sugar involved in the Calvin cycle,not in the structure of $DNA$. Therefore,this statement is false.
Conclusion: Since $S$ is true and $R$ is false,the correct option is $C$.

(B) Nucleic acids ($DNA$ and $RNA$) are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
Therefore,nucleotides are the monomeric units or building blocks of nucleic acids.

(C) Nucleic acids,specifically $DNA$ (Deoxyribonucleic acid) and $RNA$ (Ribonucleic acid),are the fundamental molecules responsible for the storage and transmission of genetic information.
$DNA$ acts as the primary genetic material in most organisms,carrying the instructions for development,functioning,and growth,which are passed from parents to offspring.
This process of passing genetic information to the next generation is known as heredity.
Therefore,nucleic acids are fundamentally associated with heredity.

(B) Nitrogenous bases are organic molecules containing nitrogen,carbon,and hydrogen atoms arranged in heterocyclic rings.
They are classified as purines (adenine and guanine) and pyrimidines (cytosine,thymine,and uracil).
Phosphorus is a component of the phosphate group in nucleotides,but it is not a constituent element of the nitrogenous base itself.
Therefore,phosphorus is not present in the structure of a nitrogenous base.

(A) Chromosomes are composed of chromatin,which consists of $DNA$ and proteins.
$DNA$ is a nucleic acid that carries genetic information.
In eukaryotes,$DNA$ is wrapped around basic proteins called histones to form nucleosomes,which further condense into chromosomes.
While both $DNA$ and proteins are essential,$DNA$ is the primary genetic material and the fundamental structural component of the chromosome's architecture.

(D) Heredity refers to the transmission of genetic information from parents to offspring.
In all living organisms,the genetic material responsible for storing and transmitting this information is $DNA$ (Deoxyribonucleic acid),which is a type of nucleic acid.
While proteins,carbohydrates,and lipids are essential biomolecules for structure and metabolism,nucleic acids are the primary molecules that carry the genetic code.

(D) Nucleic acids,such as $DNA$ and $RNA$,are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar,and a phosphate group.
The elemental composition of these components includes Carbon $(C)$,Hydrogen $(H)$,Oxygen $(O)$,Nitrogen $(N)$,and Phosphorus $(P)$.
Therefore,the elemental analysis of nucleic acids reveals the presence of $C, H, O, N,$ and $P$.

(B) Nucleic acids,such as $DNA$ and $RNA$,are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
Nucleosides consist only of a nitrogenous base and a pentose sugar,lacking the phosphate group.
Therefore,the fundamental repeating unit or monomer of a nucleic acid is the nucleotide.

(B) nucleotide is the basic structural unit of nucleic acids ($DNA$ and $RNA$).
It consists of three essential components:
$1$. $A$ pentose sugar (ribose in $RNA$ or deoxyribose in $DNA$).
$2$. $A$ nitrogenous base ($N_2$ base),which can be a purine or a pyrimidine.
$3$. $A$ phosphoric acid group (phosphate group).
Therefore,the correct combination is pentose,$N_2$ base,and phosphoric acid.

(A) $RNA$ stands for Ribonucleic Acid,which contains the pentose sugar Ribose.
$DNA$ stands for Deoxyribonucleic Acid,which contains the pentose sugar Deoxyribose.
Therefore,the correct sequence of sugars in $RNA$ and $DNA$ is Ribose and Deoxyribose respectively.