Chemistry

Biomolecules

Question:

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

Answer:

(a) Vitamin D can be stored in our body because it is a fat soluble vitamin.

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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.

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 4.

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

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.

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 8.

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

Q 9.

What is glycogen? How is it different from starch?

Q 10.

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

Q 11.

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

Q 12.

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

Q 13.

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

Q 14.

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

Q 15.

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 16.

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

Q 17.

What is the difference between a nucleoside and a nucleotide?

Q 18.

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

Q 19.

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 20.

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 21.

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

Q 22.

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

Q 23.

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

Q 24.

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

Q 25.

What are the expected products of hydrolysis of lactose?

Q 26.

Write two main functions of carbohydrates in plants.

Q 27.

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 28.

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 29.

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

Q 30.

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

Q 31.

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

Q 32.

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 33.

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

Q 34.

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 35.

What are reducing sugars?

Q 36.

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

Q 37.

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 38.

Activation energy for the acid catalysed hydrolysis of sucrose is 6.22 kJ mol-1, while hydrolysis is catalysed by the enzyme sucrase. Explain.

Q 39.

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 40.

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

Q 41.

What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?

Q 42.

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

Q 43.

What are enzymes?

Q 44.

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

Q 45.

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

Q 46.

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

Q 47.

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

Q 48.

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

Q 49.

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 50.

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