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Class 12 (PCB) Class 12 (PCM) Class 12 (Com)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 01:04 PM study24x7 study24x7

Periplaneta belongs to which phylum?

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 01:02 PM study24x7 study24x7

How far is each base pair from the next one in DNA double helix model ?

A

2 nm

B

3.4 nm

C

34 nm

D

0.34 nm

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 01:01 PM study24x7 study24x7

If a double stranded DNA has 20% of cytosine, what will be the percentage of adenine in it ?

A

20%

B

40%

C

30%

D

60%

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 01:00 PM study24x7 study24x7

In DNA strand, the nucleotides are linked together by

A

glycosidic bonds

B

phosphodiester bonds

C

peptide bonds

D

hydrogen bonds

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:59 PM study24x7 study24x7

To initiate translation, the wiRNA first bind to

A

the smaller ribosomal sub-unit the whole ribosome

B

 the larger ribosomal sub-unit

C

smaller ribosomal sub-unit

D

no such specificity exists

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:56 PM study24x7 study24x7

The amino acid attaches to the tRNA at its

A

5’- end

B

3’ – end

C

anticodon site

D

DHUIoop

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:55 PM study24x7 study24x7

In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called

A

A – DNA

B

B – DNA

C

cDNA

D

rDNA

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:44 PM study24x7 study24x7

Control of gene expression takes place at the level of

A

DNA-replication

B

transcription

C

translation

D

None of the above

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:42 PM study24x7 study24x7

Which of the following steps in transcription is catalysed by RNA polymerase ?

A

Initiation

B

Elongation

C

Termination

D

All of the above

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:41 PM study24x7 study24x7

The human chromosome with the highest and least number of genes in them are respectively

A

chromosome 21 and Y

B

chromosome 1 and X

C

chromosome 1 and Y

D

chromosome X and Y

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 15 Jan 2021 12:40 PM study24x7 study24x7

The first genetic material could be

A

protein

B

carbohydrates

C

DNA

D

RNA

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:35 AM study24x7 study24x7

What is the most popular Method used to refining copper metals?

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:32 AM study24x7 study24x7

 Which ore can be best concentrated by froth floatation process?

A

Malachite

B

Cassiterite

C

Galena

D

Magnetite

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:31 AM study24x7 study24x7

1. The electrolytic reduction technique is used in the extraction of

A

Highly electronegative elements.

B

Highly electropostive elements.

C

Metalloids

D

Transition Metals

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:28 AM study24x7 study24x7

Compound ‘A’ C5H10O forms a phenyl hydrazone and gives a negative Tollen’s reagent test and iodoform test. On reduction with Zn+Hg/HCl, compound A gives n-pentane. The compound ‘A’ is

A

Primary alcohol

B

Aldehyde

C

Secondary alcohol

D

Ketone

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:27 AM study24x7 study24x7

Benzone acid is weaker than ……… but stronger than ………

A

 p-toluic acid, o-toluic acid

B

p-nitrobenzoic acid, p-toluic acid

C

acetic acid, formic acid

D

fomic acid, acetic acid

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:24 AM study24x7 study24x7

The reagent with which both acetaldehyde and acetone react easily is

A

Fehling’s reagent

B

Grignard’s reagent

C

Schiff’s reagent

D

Tollen's ragent

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:22 AM study24x7 study24x7

Which is favourable for physical adsorption?

A

High T and high P

B

High T and low P

C

Low T and high P

D

T and P do not effect

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:20 AM study24x7 study24x7

The protective power of lyophilic colloidal sol is expressed in terms of

A

coagulation value

B

gold number

C

CMC (Critical Micelle Concentration)

D

Oxidation Numbers

Class 12 (PCB) Class 12 (PCM)
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K12PreparationGuide
5 followers study24x7 14 Jan 2021 10:19 AM study24x7 study24x7

Colloidion is 4% solution of which one of the following in alcohol-ether mixture.

A

Nitroglycerin

B

Cellulose acetate

C

Glycol dinitrate

D

Nitrocellulose

Class 12 (PCB) Class 12 (PCM)
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