Chemistry

Biomolecules

Question:

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

Answer:

Both sucrose and lactose are disaccharides. Sucrose on hydrolysis gives one molecule each of glucose and fructose but lactose on hydrolysis gives one molecule each of glucose and galactose.
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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.

Name the linkage connecting monosaccharide units in polysaccharides.

Q 4.

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

Q 5.

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

Q 6.

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

Q 7.

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

Q 8.

Why does compound (A) given below not form an oxime?
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Q 9.

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

Q 10.

What are the common types of secondary structure of proteins?

Q 11.

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 12.

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

Q 13.

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

Q 14.

Which of the following pairs represents anomers?
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Q 15.

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 16.

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

Q 17.

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

Q 18.

What is glycogen? How is it different from starch?

Q 19.

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

Q 20.

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

Q 21.

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 22.

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

Q 23.

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 24.

What is the basic structural difference between starch and cellulose?

Q 25.

Differentiate between globular and fibrous proteins.

Q 26.

What are nucleic acids ? Mention their two important functions.

Q 27.

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?
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Q 28.

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

Q 29.

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 30.

Why cannot Vitamin C be stored in our body?

Q 31.

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

Q 32.

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?
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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.

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

Q 35.

In nucleoside a base is attached at 1′ position of sugar moiety. Nucleotide is formed by linking of phosphoric acid unit to the sugar unit of nucleoside. At which position of sugar unit is the phosphoric acid linked in a nucleoside to give a nucleotide?

Q 36.

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 37.

Assertion (A): β-glycosidic linkage is present in maltose.
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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 38.

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

Q 39.

The melting points and solubility of amino acids in water are generally higher than those of corresponding haloacids. Explain.

Q 40.

How do you explain the amphoteric behaviour of amino acids?

Q 41.

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 42.

Match the vitamins given in Column I with the deficiency disease they cause given in Column II.
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Q 43.

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 44.

What are monosaccharides ?

Q 45.

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

Q 46.

What is the difference between a nucleoside and a nucleotide?

Q 47.

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?
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Q 48.

Proteins can be classified into two types on the basis of their molecular shape, i.e., fibrous proteins and globular proteins. Examples of globular proteins are
(a) insulin (b) keratin (c) albumin (d) myosin

Q 49.

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Q 50.

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