Chemistry

Biomolecules

Question:

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

Answer:

The carboxyl group of glycine and amino group of alanine when combines together, they form glycylalanine through a peptide (-CO – NH) linkage.
ncert-exemplar-problems-class-12-chemistry-biomolecules-31

previuos
next

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.

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 7.

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

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.

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

Q 10.

What is glycogen? How is it different from starch?

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 is the difference between a nucleoside and a nucleotide?

Q 18.

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

Q 19.

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

Q 20.

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

Q 21.

What are enzymes?

Q 22.

Why must vitamin C be supplied regularly in diet?

Q 23.

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

Q 24.

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 25.

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

Q 26.

What do you understand by the term glycosidic linkage?

Q 27.

Differentiate between globular and fibrous proteins.

Q 28.

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 29.

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

Q 30.

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

Q 31.

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

Q 32.

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 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.

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 35.

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

Q 36.

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

Q 37.

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

Q 38.

What are nucleic acids ? Mention their two important functions.

Q 39.

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 40.

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

Q 41.

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

Q 42.

Why cannot Vitamin C be stored in our body?

Q 43.

What are monosaccharides ?

Q 44.

Write two main functions of carbohydrates in plants.

Q 45.

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

Q 46.

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

Q 47.

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 48.

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 49.

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

Q 50.

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