Chemistry

Biomolecules

Question:

Structure of a disaccharide formed by glucose and fructose is given below. Identify anomeric carbon atoms in monosaccharide units.
ncert-exemplar-problems-class-12-chemistry-biomolecules-11

Answer:

(c) Carbon adjacent to oxygen atom in the cyclic structure of glucose or fructose is known as anomeric carbon. As shown in the structure above ‘a' and ‘b' are present at adjacent to oxygen atom. Both carbons differ in configurations of the hydroxyl group.

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Biomolecules

Q 1.

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 2.

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

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.

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

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.

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

Q 10.

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

Q 11.

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

Q 12.

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 13.

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

Q 14.

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

Q 15.

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

Q 16.

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 17.

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

Q 18.

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 19.

Structure of a disaccharide formed by glucose and fructose is given below. Identify anomeric carbon atoms in monosaccharide units.
ncert-exemplar-problems-class-12-chemistry-biomolecules-11

Q 20.

Name the linkage connecting monosaccharide units in polysaccharides.

Q 21.

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

Q 22.

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 23.

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

Q 24.

What are monosaccharides ?

Q 25.

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 26.

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

Q 27.

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

Q 28.

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

Q 29.

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

Q 30.

Coagulation of egg white on boiling is an example of denaturation of protein. Explain it in terms of structural changes.

Q 31.

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 32.

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 33.

How do you explain the absence of aldehyde group in the pentaacetate of D-glucose?

Q 34.

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

Q 35.

What is the difference between a nucleoside and a nucleotide?

Q 36.

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

Q 37.

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

Q 38.

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

Q 39.

How will you distinguish 1 ° and 2 ° hydroxyl groups present in glucose? Explain with reactions.

Q 40.

What are the expected products of hydrolysis of lactose?

Q 41.

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

Q 42.

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 43.

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

Q 44.

Enumerate the reactions of D-glucose which cannot be explained by its open chain structure.

Q 45.

Differentiate between globular and fibrous proteins.

Q 46.

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 47.

Amino acids are classified as acidic, basis or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Which of the following are acidic?
ncert-exemplar-problems-class-12-chemistry-biomolecules-13

Q 48.

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

Q 49.

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

Q 50.

Why must vitamin C be supplied regularly in diet?