Biomolecules Practice Test — Class 12 Chemistry

12th Standard Chemistry — Biomolecules: Online Practice Test

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Which one of the following rotates the plane polarized light towards left?

A.D(+) Glucose B.L(+) Glucose C.D(-) Fructose D.D(+) Galactose

The correct corresponding order of names of four aldoses with configuration given below respectively is,

A.L-Erythrose, L-Threose, L-Erythrose, D-Threose B.D-Threose, D-Erythrose, L-Threose, L-Erythrose C.L-Erythrose, L-Threose, D-Erythrose, D-Threose D.D-Erythrose, D-Threose, L-Erythrose, L-Threose

Which one of the following is a non-reducing sugar?

A.Glucose B.Sucrose C.Maltose D.Lactose

Glucose reacts with hydrogen cyanide to form a product, which on hydrolysis followed by reduction with hydrogen iodide and heat gives compound A. Identify compound A:

A.Heptanoic acid B.2-Iodohexane C.Heptane D.Heptanol

Assertion: A solution of sucrose in water is dextrorotatory. But on hydrolysis in the presence of little hydrochloric acid, it becomes levorotatory. Reason: Sucrose hydrolysis gives equal amounts of glucose and fructose. As a result, this change in sign of rotation is observed.

A.If both assertion and reason are true and reason is the correct explanation of assertion B.If both assertion and reason are true but reason is not the correct explanation of assertion C.If assertion is true but reason is false D.If both assertion and reason are false

The central dogma of molecular genetics states that the genetic information flows from:

A.Amino acids \(\rightarrow\) Protein \(\rightarrow\) DNA B.DNA \(\rightarrow\) Carbohydrates \(\rightarrow\) Proteins C.DNA \(\rightarrow\) RNA \(\rightarrow\) Proteins D.DNA \(\rightarrow\) RNA \(\rightarrow\) Carbohydrates

In a protein, various amino acids are linked together by:

A.Peptide bond B.Dative bond C.\(\alpha\)-Glycosidic bond D.\(\beta\)-Glycosidic bond

Among the following, the achiral amino acid is:

A.2-ethylalanine B.2-methylglycine C.2-hydroxymethylserine D.Tryptophan

The correct statement regarding RNA and DNA respectively is:

A.The sugar component in RNA is an arabinose and the sugar component in DNA is ribose B.The sugar component in RNA is 2'-deoxyribose and the sugar component in DNA is arabinose C.The sugar component in RNA is an arabinose and the sugar component in DNA is 2'-deoxyribose D.The sugar component in RNA is ribose and the sugar component in DNA is 2'-deoxyribose

Q10

In aqueous solution, amino acids mostly exist in the form of:

A.NH2-CH(R)-COOH B.NH2-CH(R)-COO- C.H3N+-CH(R)-COOH D.H3N+-CH(R)-COO-

Q11

Which one of the following is not produced by the human body?

A.DNA B.Enzymes C.Hormones D.Vitamins

Q12

The number of sp2 and sp3 hybridised carbons in fructose are respectively:

A.1 and 4 B.4 and 2 C.5 and 1 D.1 and 5

Q13

Vitamin B2 is also known as:

A.Riboflavin B.Thiamine C.Nicotinamide D.Pyridoxine

Q14

The pyrimidine bases present in DNA are

A.Cytosine and Adenine B.Cytosine and Guanine C.Cytosine and Thymine D.Cytosine and Uracil

Q15

Among the following L-serine is

A.(figure A)

B.(figure B)

C.(figure C)

D.(figure D)

Q16

The secondary structure of a protein refers to

A.fixed configuration of the polypeptide backbone B.hydrophobic interaction C.sequence of \(\\alpha\)-amino acids D.\(\\alpha\)-helical backbone

Q17

Which of the following vitamins is water soluble?

A.Vitamin E B.Vitamin K C.Vitamin A D.Vitamin B

Q18

Complete hydrolysis of cellulose gives

A.L-Glucose B.D-Fructose C.D-Ribose D.D-Glucose

Q19

Which of the following statement is not correct?

A.Ovalbumin is a simple food reserve in egg-white B.Blood proteins thrombin and fibrinogen are involved in blood clotting C.Denaturation makes protein more active D.Insulin maintains the sugar level of in the human body.

Q20

Glucose is an aldose. Which one of the following reactions is not expected with glucose?

A.It does not form oxime B.It does not react with Grignard reagent C.It does not form osazones D.It does not reduce tollens reagent

Q21

If one strand of the DNA has the sequence 'ATGCTTGA', then the sequence of complementary strand would be

A.TACGAACT B.TCCGAACT C.TACGTACT D.TACGRAGT

Q22

Insulin, a hormone chemically is

A.Fat B.Steroid C.Protein D.Carbohydrates

Q23

\(\\alpha\)-D (+) Glucose and \(\\beta\)-D (+) glucose are

A.Epimers B.Anomers C.Enantiomers D.Conformational isomers

Q24

Which of the following are epimers

A.D(+)-Glucose and D(+)-Galactose B.D(+)-Glucose and D(+)-Mannose C.Neither (a) nor (b) D.Both (a) and (b)

Q25

Which of the following amino acids are achiral?

A.Alanine B.Leucine C.Proline D.Glycine

Q26

Which carbon atom's configuration in D-glucose is compared with that of D-glyceraldehyde to assign the D notation?

A.C1 B.C2 C.C5 D.C6

Q27

When alpha-D-glucose and beta-D-glucose undergo mutarotation in water, they establish an equilibrium mixture with a constant specific rotation of:

A.+112 degrees B.+19 degrees C.+53 degrees D.+100 degrees

Q28

At the branching points of amylopectin in starch, new chains are linked by which type of glycosidic bond?

A.alpha(1,4) glycosidic bond B.beta(1,4) glycosidic bond C.alpha(1,6) glycosidic bond D.beta(1,6) glycosidic bond

Q29

Why are humans unable to use cellulose as a food source?

A.Cellulose contains alpha(1,4) glycosidic bonds which cannot be cleaved by human amylase. B.Humans lack the digestive enzymes like glycosidases or cellulases to hydrolyse beta(1,4) glycosidic bonds. C.Cellulose is highly branched and cannot be packed into human tissue layers. D.Cellulose undergoes spontaneous mutarotation in the body to form toxic ketoses.

Q30

Which of the following is a non-essential amino acid synthesised by the human body?

A.Valine B.Phenylalanine C.Alanine D.Leucine

Q31

At a pH value below its isoelectric point, an amino acid exists predominantly as:

A.A negatively charged anion B.A positively charged cation C.A neutral Zwitterion D.A non-polar molecule

Q32

In an alpha-helix sub-structure of proteins, the right-handed helical conformation is stabilised by hydrogen bonding between the carbonyl oxygen of the nth residue and the amino hydrogen of which residue?

A.n+2th residue B.n+3th residue C.n+4th residue D.n+5th residue

Q33

Which amino acid has a rigid cyclic structure that produces a kink in the polypeptide chain and is known as a "helix breaker"?

A.Glycine B.Proline C.Histidine D.Serine

Q34

During the denaturation of a protein, which level of protein structure remains completely intact?

A.Quaternary structure B.Tertiary structure C.Secondary structure D.Primary structure

Q35

Simple lipids classified as waxes are chemically defined as esters of long-chain fatty acids with:

A.Glycerol B.Long-chain monohydric alcohols C.Amino alcohols D.Phosphoric acid

Q36

Which class of vitamins cannot be stored in the body and must be regularly supplied through diet because any excess is excreted in urine?

A.Vitamins A and D B.Vitamins E and K C.Vitamins B and C D.Vitamins A and K

Q37

According to the text, which vitamin acts as a coenzyme in amino acid metabolism and is essential for the formation of heme in hemoglobin?

A.Vitamin B2 (Riboflavin) B.Vitamin B5 (Pantothenic acid) C.Vitamin B6 (Pyridoxine) D.Vitamin B7 (Biotin)

Q38

Which pyrimidine base is uniquely present in RNA molecules and replaces the thymine found in DNA?

A.Adenine B.Cytosine C.Uracil D.Guanine

Q39

The biological process by which a single-stranded messenger RNA (mRNA) molecule is synthesised from a DNA template strand is known as:

A.Translation B.Transcription C.Replication D.Denaturation

Q40

Chemically, hormones are organic substances secreted by endocrine glands and are classified into which two major groups?

A.Carbohydrates and lipids B.Proteins and steroids C.Amino acids and nucleotides D.Nucleic acids and vitamins

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About this Biomolecules test

This free online practice test covers Biomolecules from the 12th Standard Chemistry (Samacheer Kalvi) syllabus. Choose the number of questions and an optional time limit, then answer and submit — everything is checked in your browser, with the correct answers and a worked explanation shown at the end. For the full solutions to every question in this set, see the solved MCQs page.

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