CHAPTER 10

Biomolecules

1. CARBOHYDRATES

Objective Qs [1 mark]
1. Which of the following is a polysaccharide?
(a) Glucose
(b) Maltose
(c) Glycogen
(d) Lactose
[CBSE SQP Term-1 2021]

2. Which one of the following reactions is not explained by the open chain structure of glucose?
(a) Formation of pentaacetate of glucose with acetic anhydride.

(b) Formation of addition product with 2, 4-DNP reagent.

(c) Silver mirror formation with Tollen's reagent.

(d) Existence of alpha and beta forms of glucose.

[CBSE SQP Term-1 2021]

3. Glucose on reaction with Br2 water gives:

(a) saccharic acid
(b) hexanoic acid
(c) gluconic acid
(d) salicylic acid
[CBSE Term-1 2021]

4. Which of the following sugar is known as dextrose?

(a) Glucose
(b) Fructose
(c) Ribose
(d) Sucrose
[CBSE Term-1 2021]

5. Find incorrect statement from the following for glucose:

(a) It is present in furanose form.

(b) It is an aldohexose.

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SOLUTIONS
 (c) It does not give 2, 4-DNP test.

(d) It forms n-hexane when heated with HI.

[Delhi Gov. SQP Term-1 2021]

6. In the following reaction, identify 𝐴 and 𝐵 :

(a) A = COOH − (CH2 )4 − COOH, B = OHC (CHOCOCH3 )4 − CH2 OCOCH3

(b) A = COOH − (CH2 )4 − CHO, B = OHC − (CHOCOCH3 )4 − CH2 OCOCH3

(c) A = OHC − (CHOCOCH3 )3 − CH2 OCOCH3 B = COOH − (CH2 O)4 − CHO,

(d) A = OHC − (CHOCOCH3 )4 − CH2 OCOCH3 B = COOH − (CH2 O)4 − COOH

[CBSE SQP Term-1 2021]

7. Which one of the following statement is correct about sucrose?

(a) It can reduce tollen's reagent however cannot reduce Fehling's reagent.

(b) It undergoes mutarotation like glucose and fructose.

(c) It undergoes inversion in the configuaration on hydrolysis.

(d) It is laevorotatory in nature.

[CBSE SQP Term-I 2021]

8. 𝛼 − 𝐷 − (+) - glucose and 𝛽 − 𝐷 − (+) - glucose are:

(a) anomers

(b) enantiomers

(c) conformers

(d) epimers

[CBSE 2020]

9. Dissacharides that are reducing in nature are:

(a) sucrose and lactose

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SOLUTIONS
 (b) sucrose and maltose

(c) lactose and maltose

(d) sucrose, lactose and maltose

[CBSE SQP 2020]

In the following question, a statement of assertion (A) followed by a statement of reason (R) is given.
Choose the correct answer out of the following choices.

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).

(c) (A) is true but (R) is false.

(d) (A) is false but (R) is true.

10. Assertion (A): Sucrose is a non - reducing sugar.

Reason (R): It has glycosidic linkage.

[CBSE 2020]

Very Short & Short Qs [1 - 3 marks]

11. When sucrose is hydrolysed the optical rotation values are measured using a polarimeter and are
given in the following table:

S.No. Time (hours) Specific Rotation

1 0 +66.5∘

2 ∞ −39.9∘

(A) Account for the two specific rotation values.

(B) What is the specific name given to sucrose based on the above observation?

(C) One of the products formed during the hydrolysis of sucrose is a glucose, that reacts with
hydroxylamine to give compound A. Identify compound A.

[CBSE SQP 2023]

12. What happens when 𝐷 - glucose is treated with the following reagents?
(A) Bromine water

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SOLUTIONS
 (B) HNO3

[CBSE SQP 2022]

13. Account for the following:

(A) There are 5 − OH groups in glucose

(B) Glucose is a reducing sugar

[CBSE SQP 2022]

14. Define the following terms:

(A) Oligosaccharides
(B) Invert sugar
[CBSE 2020]

15. Name the disaccharide which on hydrolysis gives two molecules of glucose. [CBSE 2020]

16. Write the name of linkage joining two monosaccharides.

[CBSE 2020]

17. Write the products of hydrolysis of lactose.

[CBSE 2019]

18. Write chemical reactions to show that open structure of D-glucose contains the following:
(A) Straight chain

(B) Five alcohol groups

(C) Aldehyde as carbonyl group

[CBSE 2019]

19. Write the product when D-glucose react with conc. HNO3 .
[CBSE 2018]

20. Glucose on reaction with acetic anhydride gives glucose pentaacetate. What does it suggest about the
structure of glucose?
[CBSE 2017]

21. Which one of the following is a disaccharide: Starch, Maltose, Fructose, Glucose?
[CBSE 2015]

22. Write the product obtained when D-glucose reacts with H2 N − OH.

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SOLUTIONS
 [CBSE 2015]

23. Which one of the following is a monosaccharide:

Starch, Maltose, Fructose, Cellulose.

[CBSE 2015]

24. Which of the two componnents of starch is water soluble?

[CBSE 2014]

25. Write the product formed on reaction of D-glucose with Br2 water.
[CBSE 2014]

26. Write the product formed when glucose is treated with HI.
[CBSE 2014]

27. Define the following term: Polysaccharides

[CBSE 2014]

2. PROTEINS

Objective Qs [1 mark]
28. Which of the following statement is correct?
(a) Fibrous proteins are generally soluble in water.

(b) Albumin is an example of fibrous proteins. (c) In fibrous proteins, the structure is stabilised by
hydrogen bonds and disulphide bonds.

(d) pH does not affect the primary structure of protein. [CBSE SQP Term-1 2021]

29. The sequence of 𝛼-amino acids in a polypeptide chain in a protein is called its:
(a) Tertiary structure

(b) Primary structure

(c) Secondary structure

(d) None of these

[Delhi Gov. SQP Term-1 2021]

30. Complete the following analogy:

Curdling of milk : 𝐴: : 𝛼-helix : B

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SOLUTIONS
 (a) A: Primary structure, B : Secondary structure

(b) A: Denatured protein, B : Primary structure

(c) A: Secondary structure, B : Denatured protein

(d) A: Denatured protein, B : Secondary structure

[CBSE Term-1 2021]

31. Peptide linkage is present in:

(a) carbohydrates

(b) vitamins

(c) protein

(d) rubber

[CBSE 2020]

32. Amino acids are:

(a) acidic
(b) basic
(c) amphoteric
(d) neutral
[CBSE 2020]

33. In the following question, a statement of assertion (A) followed by a statement of reason (R) is given.
Choose the correct answer out of the following choices.
Assertion (A): Proteins are found to have two different types of secondary structures viz alpha-helix
and beta-pleated sheet structure.
Reason (R): The secondary structure of proteins is stabilised by hydrogen bonding.

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

(b) Both (A) and (R) are true but (R) is not the correct explanation of (A).

(c) (A) is true but (R) is false.

(d) (A) is false but (R) is true.

[CBSE SQP 2022]

Very Short & Short Qs [1 - 3 marks]

34. Differentiate between the following:

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SOLUTIONS
 (A) Amylose and Amylopectin

(B) Peptide linkage and glycosidic linkage

[CBSE 2019]

35. Name the species formed when an aqueous solution of amino acid is dissolved in water?
[CBSE SQP 2019]

36. Define the following with an example of each:

(A) Denatured Protein.

(B) Essential Amino Acid.

[CBSE 2018]

37. What is the difference between fibrous protein and globuar protein?
[CBSE 2017, 15]

38. Give one example each for fibrous and globular protein.
[CBSE 2016]

39. What is the difference between acidic amino acids and basic amino acids? [CBSE 2015]

40. What type of linkage is repsonsible for the formation of protiens?

[CBSE 2014]

3. VITAMINS, HORMONES & NUCLEIC ACIDS.

Objective Qs [1 mark]
41. The vitamins which can be stored in our body are:
(a) Vitamin A, B, D and E

(b) Vitamin A, C, D and K

(c) Vitamin A, B, C and D

(d) Vitamin A, D, E and K

[CBSE SQP 2023]

42. Match the following:

I II

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SOLUTIONS
 (i) Amino acids (A) Protein
(ii) Thymine (B) Nucleic acid
(iii) Insulin (C) DNA
(iv) posphodiester linkage (D) Zwitter ion

(v) Uracil

Which of the following is the best matched options?

(a) (i)-(A) (v)-(D), (iii)-(C) (iv)-(B)

(b) (i)-(D) (ii)-(C), (iii)-(A) (iv)-(B)

(c) (i)-(D) (v)-(D), (iii)-(A) (iv)-(B)

(d) (i)-(A) (ii)-(C), (iii)-(D) (iv)-(B)

[CBSE SQP Term-1 2021]

43. Nucleosides are composed of:

(a) a pentose sugar and phosphoric acid.

(b) a nitrogenous base and phosphoric acid.

(c) a nitrogenous base and a pentose sugar.

(d) a nitrogenous base, a pentose sugar and phosphoric acid.

[CBSE Term-1 2021]

44. The base which is present in DNA but not in RNA, is:
(a) Cytosine

(b) Guanine

(c) Adenine

(d) Thymine

[CBSE Term-1 2021]

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SOLUTIONS
 Case Based Qs [4 - 5 marks]
Read the following passage and answer the questions that follow:

45. Strengthening the Foundation: Chargaff Formulates His "Rules"

Many people believe that James Watson and Francis Crick discovered DNA in the 1950s. In reality,
this is not the case. Rather, DNA was first identified in the late 1860 s by Swiss chemist Friedrich
Miescher. Then, in the decades following Miescher's discovery, other scientists--notably, Phoebus
Levene and Erwin Chargaff--carried out a series of research efforts that revealed additional details
about the DNA molecule, including its primary chemical components and the ways in which they
joined with one another. Without the scientific foundation provided by these pioneers, Watson and
Crick may never have reached their groundbreaking conclusion of 1953: that the DNA molecule
exists in the form of a three-dimensional double helix.

Chargaff, an Austrian biochemist, as his first step in this DNA research, set out to see whether there
were any differences in DNA among different species. After developing a new paper chromatography
method for separating and identifying small amounts of organic material, Chargaff reached two major
conclusions:

(I) The nucleotide composition of DNA varies among species.

(II) Almost all DNA, no matter what organism or tissue type it comes from maintains certain
properties, even as its composition varies. In particular, the amount of adenine (A) is similar to the
amount of thymine (T), and the amount of guanine
(G) approximates the amount of cytosine (C). In other words, the total amount of purines (𝐴 + 𝐺)
and the total amount of pyrimidines (𝐶 + 𝑇) are usually nearly equal. This conclusion is now known
as "Chargaff's rule."

Chargaff's rule is not obeyed in some viruses. These either have single-stranded DNA or RNA as
their genetic material.

(A) A segment of DNA has 100 adenine and 150 cytosine bases. What is the total number of
nucleotides present in this segment of DNA?

(B) A sample of hair and blood was found at two sites. Scientists claim that the samples belong to
same species. How did the scientists arrive at this conclusion?

(C) The sample of a virus was tested and it was found to contain 20% adenine, 20% thymine, 20%
guanine and the rest cytosine. Is the genetic material of this virus (i) DNA- double helix (ii) DNA-
single helix (iii) RNA? What do you infer from this data?

OR
How can Chargaff's rule be used to infer that the genetic material of an organism is double- helix or
single- helix?

[CBSE SQP 2022]

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SOLUTIONS
 Very Short & Short Qs [1 - 3 marks]
46. (A) DNA fingerprinting is used to determine paternity of an individual. Which property of DNA
helps in the procedure?
(B) What structural change will occur when a native protein is subjected to change in pH ?

[CBSE SQP 2023]

47. Why Vitamin C can't be stored in our body?

[CBSE 2016]

48. What is the difference between a nucleotide and nucleoside?

[CBSE 2016, 14]

49. What type of linkage is present in nucleic acids?

[CBSE 2016]

50. Write the name of the vitamin whose deficiency causes bone deformities in children.
[CBSE 2015]

51. "Vitamins are organic compounds that people need in small quantities. Most vitamins need to come
from food because the body either does not produce them or produces very little. Different vitamins
play different roles in the body, and a person requires a different amount of each vitamin to stay
healthy."
Deficiency of which vitamin causes:

(A) night blindness

(B) poor coagulation of blood. [CBSE 2014]

52. Deficiency of which vitamin causes scurvy?

[CBSE 2014]

53. Why are vitamin 𝐴 and vitamin 𝐶 essential for us?

[CBSE 2014]

54. Name the base that is found in nucleotide of RNA only.

[CBSE 2014]

55. Differentiate between following:

(A) Amylose and Amylopectin

(B) Globular and Fibrous protein

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SOLUTIONS
(C) Nucleotide and Nucleoside.

[CBSE 2014]

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SOLUTIONS