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.

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

Q 2.

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

Q 3.

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 4.

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 5.

What is glycogen? How is it different from starch?

Q 6.

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

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.

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

Q 10.

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

Q 11.

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

Q 12.

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

Q 13.

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

Q 14.

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

Q 15.

What are the common types of secondary structure of proteins?

Q 16.

What is the difference between a nucleoside and a nucleotide?

Q 17.

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 18.

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

Q 19.

Name the linkage connecting monosaccharide units in polysaccharides.

Q 20.

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 21.

What are nucleic acids ? Mention their two important functions.

Q 22.

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

Q 23.

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

Q 24.

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

Q 25.

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 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.

Write two main functions of carbohydrates in plants.

Q 28.

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

Q 29.

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

Q 30.

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 31.

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

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.

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

Q 34.

What are the expected products of hydrolysis of lactose?

Q 35.

What are monosaccharides ?

Q 36.

How do you explain the amphoteric behaviour of amino acids?

Q 37.

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

Q 38.

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

Q 39.

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

Q 40.

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 41.

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 42.

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

Q 43.

What are enzymes?

Q 44.

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 45.

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 46.

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 47.

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

Q 48.

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 49.

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

Q 50.

Glucose or sucrose are soluble in water but cyclohexane and benzene (simple six membred ring compounds) are insoluble in water Explain.