Chemistry

Biomolecules

Question:

Name the linkage connecting monosaccharide units in polysaccharides.

Answer:

The monosaccharide units are linked through glycosidic linkage in a polysaccharide. 

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Biomolecules

Q 1.

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 2.

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

Q 3.

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

Q 4.

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

Q 5.

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

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

Q 9.

What is glycogen? How is it different from starch?

Q 10.

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

Q 11.

What are the common types of secondary structure of proteins?

Q 12.

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

Q 13.

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 14.

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

Q 15.

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

Q 16.

Name the linkage connecting monosaccharide units in polysaccharides.

Q 17.

What are enzymes?

Q 18.

What is the difference between a nucleoside and a nucleotide?

Q 19.

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

Q 20.

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

Q 21.

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

Q 22.

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

Q 23.

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

Q 24.

Why must vitamin C be supplied regularly in diet?

Q 25.

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 26.

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

Q 27.

What do you understand by the term glycosidic linkage?

Q 28.

Differentiate between globular and fibrous proteins.

Q 29.

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 30.

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

Q 31.

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

Q 32.

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

Q 33.

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

Q 34.

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 35.

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

Q 36.

What are nucleic acids ? Mention their two important functions.

Q 37.

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?  

Q 38.

α-Helix is a secondary structure of proteins formed by twisting of polypeptide chain into right handed screw like structures. Which type of interactions are responsible for making the a-helix structure stable?

Q 39.

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

Q 40.

Why cannot Vitamin C be stored in our body?

Q 41.

Write two main functions of carbohydrates in plants.

Q 42.

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

Q 43.

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

Q 44.

Which sugar in called invert sugar? Why is it called so?

Q 45.

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

Q 46.

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 47.

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

Q 48.

What are monosaccharides ?

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.

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