Chemistry

Biomolecules

Question:

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

Answer:

(b, d) Sucrose is a disaccharide and a non-reducing sugar.

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Biomolecules

Q 1.

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

Q 2.

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 3.

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

Q 4.

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 5.

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

Q 6.

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

Q 7.

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

Q 8.

What is glycogen? How is it different from starch?

Q 9.

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

Q 10.

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

Q 11.

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

Q 12.

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 13.

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

Q 14.

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

Q 15.

What is the difference between a nucleoside and a nucleotide?

Q 16.

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

Q 17.

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 18.

Write two main functions of carbohydrates in plants.

Q 19.

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

Q 20.

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

Q 21.

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

Q 22.

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 23.

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

Q 24.

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

Q 25.

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

Q 26.

Name the sugar present in milk. How many monosaccharide units are present in it? What are such oligosaccharides called?

Q 27.

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

Q 28.

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 29.

What happens when D-glucose is treated with . the following reagents.
(i)HI (ii) Bromine water (iii) HNO3

Q 30.

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

Q 31.

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 32.

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

Q 33.

Which of the following monosaccharides are present as five membered cyclic structure (foranose structure)?
(a) Ribose (b) Glucose (c) Fructose (d) Galactose

Q 34.

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

Q 35.

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

Q 36.

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 37.

Classify the following into monosaccharides and disaccharides. Ribose, 2-deoxyribose, maltose, galactose, fructose and lactose.

Q 38.

What is the basic structural difference between starch and cellulose?

Q 39.

Write the important structural and functional differences between DNA and RNA.

Q 40.

Three cyclic structures of monosaccharides are given below which of these are anomers.
ncert-exemplar-problems-class-12-chemistry-biomolecules-9

Q 41.

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 42.

How do you explain the presence of five -OH groups in glucose molecule?

Q 43.

Protein found in a biological system with a unique three dimensional structure and biological activity is called a native protein. When a protein in its native form, is subjected to a physical change like change in temperature or a chemical change like, change in pH, denaturation of protein takes place. Explain the cause.

Q 44.

Match the vitamins given in Column I with the deficiency disease they cause given in Column II.
ncert-exemplar-problems-class-12-chemistry-biomolecules-37

Q 45.

Assertion (A): Glycine must’be taken through diet.
Reason (R): It is an essential amino acid.

Q 46.

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 47.

What are the hydrolysis products of (i) sucrose, and (ii) lactose?

Q 48.

Which of the following pairs represents anomers?
ncert-exemplar-problems-class-12-chemistry-biomolecules-3
ncert-exemplar-problems-class-12-chemistry-biomolecules-4

Q 49.

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 50.

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