Atomic Energy Central School Kudankulam

Atomic Energy Central School Kudankulam

BIOMOLECULES WORKSHEET
Class 12 - Chemistry

1. Commercially glucose is obtained by [1]

a) hydrolysis of sucrose b) boiling sucrose with dilute HCl or

H2SO4 in alcoholic solution

c) hydrolysis of starch by boiling it with dilute d) crushing ripe grapes

H2SO4 at 393 K under pressure.

2. Maltose is made of: [1]

a) ∝ -D-glucose b) ∝ - D-glucose and β - D -glucose

c) Glucose and fructose d) D-fructose

3. Which of the following bases is not present in DNA? [1]

a) Adenine b) Cytosine

c) Uracil d) Thymine
4. Complete hydrolysis of RNA yields [1]

a) nitrogen containing base b) phosphoric acid

c) All of these d) a pentose sugar

5. Which one is the complementary base of cytosine in one strand to that in other strand of DNA? [1]

a) Uracil b) Thymine

c) Guanine d) Adenine

6. i. Name any two bases which are common to both DNA and RNA. [1]
ii. Which vitamin deficiency causes:
1. Bone deformities in children?
2. Pernicious anaemia?

7. i. What is the difference between a nucleoside and nucleotide? [1]

ii. Write one difference between α-helix and β-pleated sheet structures of protein.
8. Which one of the following is a polysaccharide? [1]
Sucrose, Glucose, Starch, Fructose
9. Define the following terms: [1]
i. Glycosidic linkage
ii. Native protein

10. i. Glucose on reaction with acetic acid gives glucose pentaacetate. What does it suggest about the structure of [1]

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 glucose?
ii. Write difference between fibrous protein and globular protein. Give two points.
11. Draw open chain structure of aldopentose and aldohexose. How many asymmetric carbons are present in each? [2]
12. a. What are the hydrolysis products of (i) Lactose, (ii) Maltose? [2]
b. Give the basic structural difference between starch and cellulose.
13. Define vitamins and state their classification. List two vitamins of each class. [2]
14. Differentiate between the following: [2]
a. Fibrous protein and Globular protein
b. Essential amino acids and Non-essential amino acids
c. Amylose and Amylopectin
15. Give reason: Amylose present in the saliva becomes inactive in the stomach. [2]
16. Define the following as related to proteins. [3]
a. Peptide linkage
b. Primary structure
c. Denaturation
17. Differentiate the following: [3]
i. Fibrous protein and Globular protein
ii. Essential amino acids and Non-essential amino acids
iii. DNA and RNA
18. Monosaccharides contain carbonyl group hence are classified, as aldose or ketose. The number of carbon atoms [3]
present in the monosaccharide molecule is also considered for classification. In which class of monosaccharide
will you place fructose?
19. How are carbohydrates classified? [3]
20. Enumerate the reactions of D-glucose which cannot be explained by its open chain structure. [3]
21. On the basis of which evidences D-glucose was assigned the following structure? [5]
CHO
|

( CHOH)
|
4

CH2 OH

22. Write the structures of fragments produced on the complete hydrolysis of DNA. How are they linked in DNA [5]
molecule? Draw a diagram to show the pairing of nucleotide bases in the double helix of DNA.
23. Read the following text carefully and answer the questions that follow: [4]
Carbohydrates are optically active polyhydroxy aldehydes and ketones. They are also called saccharides. All
those carbohydrates which reduce Fehling’s solution and Tollen’s reagent are referred to as reducing sugars.
Glucose, the most important source of energy for mammals, is obtained by the hydrolysis of starch. Vitamins are
accessory food factors required in the diet. Proteins are the polymers of α-amino acids and perform various
structural and dynamic functions in the organisms. Deficiency of vitamins leads to many diseases.
i. The penta-acetate of glucose does not react with Hydroxylamine. What does it indicate? (1)
ii. Why cannot vitamin C be stored in our body? (1)
iii. Define the following as related to proteins: (2)
i. Peptide linkage
ii. Denaturation

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 OR
Define the following as related to carbohydrates: (2)
i. Anomers
ii. Glycosidic linkage
24. Read the following text carefully and answer the questions that follow: [4]
When a solution of an α-amino acid is placed in an electric field depending on the pH of the medium, the
following three cases may happen.
+ + + +
H H
− −
H2 N C HRC OO ⟷ H3 N C HRC OO ⟷ H3 N C HRC OOH
− −
II OH I OH III

I. In alkaline solution, α-amino acids exist as anion II, and there is a net migration of amino acids towards the
anode.
II. In acidic solution, α-amino acids exist as cation III, and there is a net migration of amino acid towards the
cathode.
III. If II and III are exactly balanced there is no net migration; under such conditions, anyone molecule exists as
a positive ion and as a negative ion for exactly the same amount of time, and any small movement in the
direction of one electrode is subsequently canceled by an equal movement back toward the other electrode.
The pH of the solution in which particular amino acid does not migrate under the influence of an electric
field is called the isoelectric point of that amino acid.
i. In aqueous solutions, amino acids mostly exist as (1)
ii. Amino acids are least soluble (1)
iii. The pK a1 and pK a2 of an amino acid are 2.3 and 9.7 respectively. The isoelectric point of the amino acid.
(2)
OR

Arrange in order of increasing acid strengths. (2)

25. Assertion (A): Proteins are found to have two different types of secondary structures viz alphahelix and beta [1]
pleated sheet structure.
Reason (R): The secondary structure of proteins is stabilized by hydrogen bonding.

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

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

26. Assertion (A): Glucose is a reducing sugar. [1]
Reason (R): Despite having an aldehydic group, glucose does not give 2,4-DNP test.

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

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

27. Assertion (A): The newly formed RNA dictates the synthesis of protein at the ribosome. [1]

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 Reason (R): DNA has a double-helical structure while RNA has a single-stranded structure.

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

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

28. Assertion (A): Vitamin B5 is also called as pyridoxin. [1]

Reason (R): Deficiency of vitamin B5 causes dermatitis and dementia.

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

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

29. Assertion (A): Vitamin C cannot be stored in our body. [1]
Reason (R): Vitamin C is fat soluble and is excreted from the body in urine.

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

c) Assertion (A) is true, but Reason (R) is d) Assertion (A) is false, but Reason (R) is
false. true.
30. Assertion (A): Sucrose is a disaccharide. [1]
Reason (R): Sucrose is dextro rotatory.

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

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

31. Optical rotations of some compounds along with their structures are given below which of them have D [1]
configuration.

a) I, II, III b) I, II

c) II, III d) III

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