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Class 12 Important Questions for Chemistry - Biomolecules

NCERT Exemplar Class 12 Chemistry is very important resource for students preparing for XII Board Examination. Here we have provided NCERT Exemplar Problems Solutions along with NCERT Exemplar Problems Class 12.

Question from very important topics are covered by NCERT Exemplar Class 12. You also get idea about the type of questions and method to answer in your class 12th examination.
Click Here for Class 12 Chemistry Notes
Here you can get Class 12 Important Questions Chemistry based on NCERT Text book for Class XII. Chemistry Class 12 Important Questions are very helpful to score high marks in board exams. Here we have covered Important Questions on Biomolecules for Class 12 Chemistry subject.

Chemistry Important Questions Class 12 are given below.

Multiple Choice Questions (Type-I)

1. Which of the following pairs represents anomers?

2. 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?

3. Which of the following B group vitamins can be stored in our body?

(i) Vitamin B₁

(ii) Vitamin B₂

(iii) Vitamin B₆

(iv) Vitamin B₁₂

Multiple Choice Questions (Type-II)
Note : In the following questions two or more options may be correct.

1. Amino acids are classified as acidic, basic or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Which of the following are acidic?

Short Answer Type Questions

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

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

3. 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?

4. Name the linkage connecting monosaccharide units in polysaccharides.

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

6. 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?

7. The letters 'D' or 'L' before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer. This refers to their relation with one of the isomers of glyceraldehyde. Predict whether the following compound has 'D' or 'L' configuration.

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

9. Which sugar is called invert sugar? Why is it called so?

10. Amino acids can be classified as α-, β-, γ-, δ- and so on depending upon the relative position of amino group with respect to carboxyl group. Which type of amino acids form polypeptide chain in proteins?

11. 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 α-helix structure stable?

12. 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.

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

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

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

16. Why must vitamin C be supplied regularly in diet?

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

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

19. Structures of glycine and alanine are given below. Show the peptide linkage in glycylalanine.

20. 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.

21. Activation energy for the acid catalysed hydrolysis of sucrose is 6.22 kJ mol⁻¹, while the activation energy is only 2.15 kJ mol⁻¹ when hydrolysis is catalysed by the enzyme sucrase. Explain.

22. How do you explain the presence of an aldehydic group in a glucose molecule?

23. Which moieties of nucleosides are involved in the formation of phosphodiester linkages present in dinucleotides? What does the word diester in the name of linkage indicate? Which acid is involved in the formation of this linkage?

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

25. Which monosaccharide units are present in starch, cellulose and glucose and which linkages link these units?

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

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

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

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

Matching Type Questions
Note : Match the items of Column I and Column II in the following questions. More than one option in Column II may match with the items given in Column I.

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

2. Match the following enzymes given in Column I with the reactions they catalyse given in Column II.

Assertion and Reason Type Questions
Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(i) Assertion and reason both are correct statements and reason explains the assertion.
(ii) Both assertion and reason are wrong statements.
(iii) Assertion is correct statement and reason is wrong statement.
(iv) Assertion is wrong statement and reason is correct statement.
(v) Assertion and reason both are correct statements but reason does not explain assertion.

1. Assertion : D (+) - Glucose is dextrorotatory in nature.
Reason : 'D' represents its dextrorotatory nature.

2. Assertion : Vitamin D can be stored in our body.
Reason : Vitamin D is fat soluble vitamin.

3. Assertion : β-glycosidic linkage is present in maltose,

Reason : Maltose is composed of two glucose units in which C-1 of one glucose unit is linked to C-4 of another glucose unit.

4. Assertion : All naturally occurring α-amino acids except glycine are optically active.
Reason : Most naturally occurring amino acids have L-configuration.

5. Assertion : Deoxyribose, C₅H₁₀O₅ is not a carbohydrate.
Reason : Carbohydrates are hydrates of carbon so compounds which follow Cx(H₂O)y formula are carbohydrates.

6. Assertion : Glycine must be taken through diet.
Reason : It is an essential amino acid.

7. Assertion : In presence of enzyme, substrate molecule can be attacked by the reagent effectively.
Reason : Active sites of enzymes hold the substrate molecule in a suitable position

Long Answer Type Questions

1. Write the reactions of D-glucose which can't be explained by its open-chain structure. How can cyclic structure of glucose explain these reactions?

2. On the basis of which evidences D-glucose was assigned the following structure?

3. 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.

4. Explain the terms primary and secondary structure of proteins. What is the difference between α-helix and β-pleated sheet structure of proteins?

5. Write the structures of fragments produced on complete hydrolysis of DNA. How are they linked in DNA molecule? Draw a diagram to show pairing of nucleotide bases in double helix of DNA.

Answers to Multiple Choice Questions

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Class 12 Important Questions for Chemistry - Biomolecules

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NCERT Exemplar Class 12 Chemistry is very important resource for students preparing for XII Board Examination. Here we have provided NCERT Exemplar Problems Solutions along with NCERT Exemplar Problems Class 12. Question from very important topics are covered by NCERT Exemplar Class 12.

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1. In double helix of DNA, the two strands are

a) coiled around a common axis
b) coiled differently
c) coiled over protein sheath
d) coiled around each other

2. Living cell contains 60-95% water. Water present in human body is 3. Nucleotides are building blocks of nucleic acids. Each nucleotide is a composite molecule formed by
4. The major role of minor elements inside living organisms is to act as
5. Lipids are insoluble in water because lipid molecules are
6. ATP is
7. Which of the following have carbohydrate as prosthetic group
8. Lactose is composed of

9. In which of the following groups are all polysaccharides?
10. Amino acids are produced from
11. In RNA, thymine is replaced by 12. Which purine base is found in RNA?
13. Which of the following nucleotide sequences contains four pyrimidine bases?
14. Cellulose, the most important constituent of plant cell wall is made up of
15. Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all of these

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Multiple Choice Questions on Biomolecules

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1. In double helix of DNA, the two strands are a) coiled around a common axis b) coiled differently c) coiled over protein sheath d) coiled around each other 2. Living cell contains 60-95% water. Water present in human body is 3. Nucleotides are building blocks of nucleic acids.