NCERT Solution Chemistry Class 12 Chapter 14 Biomolecules
NCERT Solution Chemistry Class 12 Chapter 14 Biomolecules all questions and answers. Chemistry Class 12 14th Chapter Biomolecules exercise solution and experts answer. As one of online learning platforms, we (netex.) are excited to offer the NCERT Solution Chemistry Class 12 Chapter 14. This solution is designed to help students who are looking to brush up on their Chemistry concepts on Chapter 14 Biomolecules.
Questions And Answers
(1) What are monosaccharides?
Ans- Monosaccharide are smallest fundamental unit of carbohydrate , which cannot be hydrolyzed to broken down into simple sugar .
e.g. glucose, fructose, ribose, etc.
(2) What are reducing sugars?
Ans-The carbohydrates which can acts as reducing agent has keton or aldehyde group is called reducing sugar . It can reduce Fehling’s solution and Tollens’ reagent because it can donate electrons. Almost all the monosachharides can acts as monosacchirides.
e.g.- glucose , fructose, glyceraldehydes , lactose , arabinose and maltose.
Exception – sucrose.
(3) Write two main functions of carbohydrates in plants.
Ans- Carbohydrate plays vital role in functional characteristics of plants
(i) Starch is polymeric chain of carbohydrate consists of glucose units. Starch is main nutrient source in food .
(ii) Cellulose is polymeric chain of carbohydrate consists D-glucose. It is basic structural component in cell wall of plant cell.
(4) Classify the following into monosaccharides and disaccharides. Ribose, 2- deoxyribose, maltose, galactose, fructose and lactose.
Ans-
Monosaccharides |
Disaccharides |
Galactose | Lactose |
Fructose | Maltose |
Ribose | |
2-deoxyribose |
(5) What do you understand by the term glycosidic linkage?
Ans- It is covalent bond between two monosaccharides that are joined together by an oxygen atom is known as glycosidic linkage .
e.g. linkage in DNA , Chitin
Glycosidic linkage in sucrose as follows –
(6) What is glycogen? How is it different from starch?
Ans- Glycogen is polysaccharide of α-D-glucose. its structure is similar to amylopectin component found in starch . glycogen is more highly branched than starch. Starch are synthesised by plant whereas glycogens synthesis occurs in animal tissue. it is present in various organs like liver, muscles , brain etc. enzymes break down the glycogen into glucose , when glucose required in body .
(7) What are the hydrolysis products of
(i) sucrose and
(ii) lactose?
Ans- On hydrolysis, sucrose breaks glycosidic linkage and forms one molecule of -D glucose and one molecule of β- D-fructose.
(8) What is the basic structural difference between starch and cellulose?
Ans- Starch is a branched chain polymer of α-D-glucose units in which chain is formed by C1–C4 glycosidic linkage .Cellulose is a straight chain polysaccharide consists only of β-D-glucose units which are joined by glycosidic linkage between C1 of one glucose unit and C4 of the next glucose unit.
(9) What happens when D-glucose is treated with the following reagents?
(i) HI
(ii) Bromine water
(iii) HNO3
Ans-
(i) When glucose is treated with HI in presence of heat. it reduces and gives
(10) Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.
Ans-
(1) glucose does not give Schiff’s test and 2, 4-DNP test, although aldehydes shows both test.
(2) Glucose does not react with NaHSO4 to form the hydrogen sulphite addition product.
(2) The pentaacetate of glucose does not react with hydroxylamine. From this it can conclude that a free -CHO group is absent in glucose.
(3) Glucose has in two crystalline forms i.e. and β. Both forms are crystallises at different temperatures although there is not much difference in melting point. such behaviour cannot be explained by the open chain structure of glucose.
(11) What are essential and non-essential amino acids? Give two examples of each type.
Ans- The amino acids that can be synthesised in the body with help of precursors and nutrients , are called as non- essential amino acids. Non- essential amino acids – Aspartic acid, Cysteine, Glutamic acid, Glutamine, Glycine etc. The amino acids that can cannot be synthesised in the body and to be obtained through diet, are known as essential amino acids.
Essential amino acids – lysine, leucine, methionine, phenylalanine etc.
(12) Define the following as related to proteins
(i) Peptide linkage
(ii) Primary structure
(iii) Denaturation.
Ans-
(i) Peptide linkage- The covalent bond of amide formed between –COOH group and –NH2 group is termed as peptide linkage. When two molecules of same or different amino acids combines with the amino group of one molecule with the carboxyl group of the other.
(ii) Primary structure of proteins: Primary structure of protein is a polypeptide chain having basic fundamental unit of amino acids held by covalent bond. the sequence of amino acids forms a different protein.
(iii) Denaturation- the highly ordered structure of the protein in its natural structure is termed as native state. Weak hydrogen bonds are responsible for high ordered structure of protein . Denaturation is the breaking of the weak linkages of hydrogen bonds in a protein molecule.
(13) What are the common types of secondary structure of proteins?
Ans- The α helix and the β pleated sheet are two types of secondary structure of proteins. The secondary structure of protein are structure in which a long polypeptide chain can exist. α helix is a most common structure of protein consists of amino acids in helical shape. β-sheets consist β-strands and long chain of polypeptide joined together by hydrogen bonds.
(14) What type of bonding helps in stabilising the α-helix structure of proteins?
Ans- α helix is a most common structure of protein consists of amino acids in helical shape. hydrogen bonds gets twisted into a right hand direction with the –NH group to form polypeptide chain . hence Hydrogen bonding helps in stabilizing the α helix structure of proteins.
(15) Differentiate between globular and fibrous proteins.
Ans-
Sr. No. | Globular Proteins | Fibrous Proteins |
(1) | This structure results when the chains of polypeptides coil around to give a spherical shape. | When the polypeptide chains run parallel and are held together by hydrogen and disulphide bonds,
then fibre– like structure is formed. |
(2) | Globular protiens are usually
soluble in water. |
Fibrous proteins are usually insoluble in water. |
(3) | e.g. Insulin , albumins | e.g. Keratin, myosin |
(16) How do you explain the amphoteric behaviour of amino acids?
Ans- An amino acid is made up of amino group (−NH2) and acidic carboxyl group (−COOH) . amino is basic and carboxylic group is acidic in nature. Amino acids , in aqueous solution an equilibrium state occurs and forms dipolar ion termed as zwitter ion. therefore amino acids can acts as both acid and base.
(17) What are enzymes?
Ans- Protiens which are acts as catalysts in biological reactions are called enzymes. Enzymes are very specific for a particular substrate in specific biological reaction. They are generally named after the compounds in reaction in which involved. e.g. the maltase is the enzyme that catalyses hydrolysis of maltose into glucose is named as.
(18) What is the effect of denaturation on the structure of proteins?
Ans- The highly ordered structure of the protein in its natural structure is termed as native state. Weak hydrogen bonds are responsible for high ordered structure of protein . Denaturation is the breaking of the weak linkages of hydrogen bonds in a protein molecule. hence structure of globules unfold and helical shape disturbed therefore, protein loses its biological activity.
(19) How are vitamins classified? Name the vitamin responsible for the coagulation of blood.
Ans- Classification of vitamins based on their solubility is as follows –
(i) Fat soluble vitamins: Fat soluble vitamins are soluble in lipids, fats and oils. These vitamins are insoluble in water.
e.g. vitamins A, D, E and K.
(ii) Water soluble vitamins: Water soluble vitamins are soluble in water but insoluble in fats and oil.
e.g. Vitamin B , Vitamin C .
Vitamin K is responsible for the coagulation of blood.
(20) Why are vitamin A and vitamin C essential to us? Give their important sources.
Ans- Deficiency of Vitamin A causes eyes disease and disorders such as night blindness and xeropthalmia causes dry eye. Vitamin C are important because deficiency of C vitamin causes dental problem , Scurvy , anaemia , dry hair and skin. Sources of Vitamin A – green leafy vegetables, Carrots, butter and milk
Sources of Vitamin C = Citrus fruits such as oranges , peppers.
(21) What are nucleic acids? Mention their two important functions.
Ans- Nucleic acids are the biopolymers nucleotides as simple structural unit. nucleotides composed by components as such as sugar, phosphate and nitrogenous bases. DNA and RNA are two main type of nucleic acids.
The transmission and long term storage of genetic information is the main function of DNA. RNA creates proteins through translation. Also, RNA carries genetic information that is translated by ribosomes into various proteins.
(22) What is the difference between a nucleoside and a nucleotide?
Ans-
Sr. No |
Nucleoside |
Nucleotide |
1) | It consists of sugar and base without contain phosphate group. | In, nucleotide, the base is attached to 1′ position of sugar and phosphate group is present. |
2) | Used as anti-cancer agent. | One of the cancer causing agent. |
(23) The two strands in DNA are not identical but are complementary. Explain. Ans- Two nucleic acid is polymeric chain of nucleotides are joined in double helical structure and held by hydrogen bonds between pairs of bases. The hydrogen bonds are formed between particulars pairs of bases. adenine forms hydrogen bonds with thymine whereas cytosine forms hydrogen bonds with guanine. Therefore, two strands are complimentary to each other.
(24) Write the important structural and functional differences between DNA and RNA.
Ans-
Sr.No. |
DNA |
RNA |
1) | DNA stands for Deoxyribonucleic acid | RNA stands for Ribonucleic acid |
2) | Double helix structure | Single helix structure |
3) | Adenine, Guanine, Cytosine, Thymine are the bases present in DNA. | Adenine, Guanine, Cytosine, Uracil are the bases present in RNA. |
4) | The transmission and long term storage of genetic information is the main function of DNA. | RNA creates proteins through translation. Also, RNA carries genetic information that is translated by ribosomes into various proteins. |
(25) What are the different types of RNA found in the cell?
Ans- There are three types of RNA molecules having different functional characteristics.
(1) messenger RNA (m-RNA)
(2) ribosomal RNA (r-RNA)
(3) transfer RNA (t-RNA).
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