Chemistry

Biomolecules

Question:

Monosaccharides contain carbonyl group hence are classified, as aldose or ketose. The number of carbon atoms present in the monosaccharide molecule are also considered for classification. In which class of monosaccharide will you place fructose?  

Answer:

Monosaccharides contain carbonyl group. Hence, are classified as aldose or ketose.
When aldehyde group is present, the monosaccharides are known as aldose. When ketone group is present, the monosaccharides are known as ketose. Fructose has molecular formula C6H12O6  containing six carbon and keto group and is classified as ketohexose.
ncert-exemplar-problems-class-12-chemistry-biomolecules-20

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Biomolecules

Q 1.

What are essential and non-essential amino acids? Give two examples of each type.

Q 2.

Three structures are given below in which two glucose units are linked. Which of these linkages between glucose units are between C1 and C4 and which linkages are between C1 and C6?
ncert-exemplar-problems-class-12-chemistry-biomolecules-12

Q 3.

During curdling of milk, what happens to sugar present in it?

Q 4.

Describe the term D- and L-configuration used for amino acids with examples.

Q 5.

Assertion (A): Deoxyribose, C5H10O4 is not a carbohydrate.
Reason (R): Carbohydrates are hydrates of carbon so compounds which follow Cx(H2O)y formula are carbohydrates.

Q 6.

Aldopentoses named ribose and 2-deoxyribose are found in nucleic acids.
What is their relative configuration?

Q 7.

The letters ' D ' or ' L' before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer.
ncert-exemplar-problems-class-12-chemistry-biomolecules-21
This refers to their relation with one of the isomers of glyceraldehydes. Predict whether the following compound has ‘D' or ‘L' configuration.

Q 8.

What is glycogen? How is it different from starch?

Q 9.

When RNA is hydrolysed, there is no relationship among the quantities of different bases obtained. What does this fact suggest about the structure of RNA?

Q 10.

Assertion (A): Vitamin D can be stored in our body.
Reason (R): Vitamin D is fat soluble vitamin.

Q 11.

Why does compound (A) given below not form an oxime?
ncert-exemplar-problems-class-12-chemistry-biomolecules-26

Q 12.

What is the difference between a nucleoside and a nucleotide?

Q 13.

Which of the following terms are correct about enzyme?
(a) Proteins (b) Dinucleotides
(c) Nucleic acids (d) Biocatalysts

Q 14.

Why are vitamin A and vitamin C essential to us? Give their important sources.

Q 15.

How do you explain the presence of all six carbon atoms in glucose in a straight chain?

Q 16.

Assertion (A): β-glycosidic linkage is present in maltose.
ncert-exemplar-problems-class-12-chemistry-biomolecules-39
Reason (R): Maltose is composed of two glucose units in which C-l of one glucose unit is linked to C-4 of another glucose unit.

Q 17.

Name the linkage connecting monosaccharide units in polysaccharides.

Q 18.

Which monosaccharide units are present in starch, cellulose and glycogen and which linkages link these units?

Q 19.

How do enzymes help a substrate to be attacked by the reagent effectively?

Q 20.

Where does the water present in the egg go after boiling the egg?

Q 21.

What are the common types of secondary structure of proteins?

Q 22.

What type of bonding helps in stabilising the α-helix structure of proteins?

Q 23.

What is the effect of denaturation on the structure of proteins?

Q 24.

ncert-exemplar-problems-class-12-chemistry-biomolecules-23

Q 25.

Carbohydrates are essential for life in both plants and animals. Name the carbohydrates that are used as storage molecules in plants and animals, also name the carbohydrate which is present in wood or in the fibre of cotton cloth.

Q 26.

Carbohydrates are classified on the basis of their behaviour on hydrolysis and also as reducing or non-reducing sugar. Sucrose is a .
(a) monosaccharide (b) disaccharide
(c) reducing sugar (d) non-reducing sugar

Q 27.

Some enzymes are named after the reaction, where they are used. What name is given to the class of enzymes which catalyse the oxidation of one substrate with simultaneous reduction of another substrate?

Q 28.

Amino acids behave like salts rather than simple amines or carboxylic acids. Explain.

Q 29.

How are vitamins classified? Name the vitamin responsible for the coagulation of blood.

Q 30.

Which of the following are purine bases?
(a) Guanine (b) Adenine (c) Thymine (d) Uracil

Q 31.

Why must vitamin C be supplied regularly in diet?

Q 32.

Sucrose is dextrorotatory but the mixture obtained after hydrolysis is laevorotatory. Explain.

Q 33.

The two strands in DNA are not identical but are complementary. Explain.

Q 34.

ncert-exemplar-problems-class-12-chemistry-biomolecules-15

Q 35.

In fibrous proteins, polypeptide chains are held together by
(a) van der Waals forces (b) disulphide linkage
(c) electrostatic forces of attraction (d) hydrogen bonds

Q 36.

Under what conditions glucose is converted to gluconic and saccharic acid?

Q 37.

Match the following enzyme given in Column I with the reactions they catalyse given in Column II.
ncert-exemplar-problems-class-12-chemistry-biomolecules-38

Q 38.

Assertion (A): All naturally occurring a-amino acids except glycine are optically active.
Reason (R): Most naturally occurring amino acids have L-configuration.

Q 39.

Write two main functions of carbohydrates in plants.

Q 40.

What are enzymes?

Q 41.

Structures of glycine and alanine are given below. Show the peptide linkage in glycylalanine.
ncert-exemplar-problems-class-12-chemistry-biomolecules-30

Q 42.

What are glycosidic linkages? In which type of biomolecules are they present?

Q 43.

Assertion (A): In presence of enzyme, substrate molecule can be attacked by the reagent effectively.
Reason (R): Active sites of enzymes hold the substrate molecule in a suitable position.

Q 44.

What is the basic structural difference between starch and cellulose?

Q 45.

How do you explain the amphoteric behaviour of amino acids?

Q 46.

In disaccharides, if the reducing groups of monosaccharides, i.e., aldehydic or ketonic groups are bonded, these are non-reducing sugars. Which of the following disaccharide is a non-reducing sugar?
ncert-exemplar-problems-class-12-chemistry-biomolecules-5

Q 47.

Optical rotations of some compounds along with their structures are given below which of them have D configuration.
ncert-exemplar-problems-class-12-chemistry-biomolecules-10

Q 48.

Proteins can be classified into two types on the basis of their molecular shape, i.e., fibrous proteins and globular proteins. Examples of globular proteins are
(a) insulin (b) keratin (c) albumin (d) myosin

Q 49.

Which of the following carbohydrates are branched polymer of glucose?
(a) Amylose (b) Amylopectin (c) Cellulose (d) Glycogen

Q 50.

In nucleoside a base is attached at 1′ position of sugar moiety. Nucleotide is formed by linking of phosphoric acid unit to the sugar unit of nucleoside. At which position of sugar unit is the phosphoric acid linked in a nucleoside to give a nucleotide?