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Published on: 25/05/2021
QB365 Provides the updated NCERT Examplar Questions for Class 12 Biology, and also provide the detail solution for each and every ncert examplar questions , QB365 will give all kind of study materials will help to get more marks
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Questions + Answers key
Take MCQ Biology Test1.
The promoter site and the terminator site for transcription are located at
3' (downstream) end and 5' (upstream) end, respectively of the transcription unit.
5' (upstream) end and 3' (downstream) end, respectively of the transcription unit.
the 5' (upstream) end.
the 3' (downstream) end.
2.
The fact that a purine base always paired through hydrogen bonds with a pyrimidine base leads to, in the DNA double helix
the antiparallel nature
the semiconservative nature
uniform width throughout DNA
uniform length in all DNA.
3.
To initiate translation, the mRNA first binds to:
The smaller ribosomal sub-unit
The larger ribosomal sub-unit
The whole ribosomal
No such specificity exists
4.
The amino acid attaches to the tRNA at its:
5' - end
3' - end
Anti codon site
DHU loop
5.
If the base sequence of a codon in mRNA is 5' - AUG-3', the sequence of tRNA pairing with it must be:
5' - UAC -3'
5' - CAU -3'
5' - AUG -3'
5' - GUA -3'
6.
The RNA polymerase holoenzyme transcribes:
the promoter, structural gene and the terminators region
the promoter,
the structural gene and the terminators regions
the structural gene only
7.
If the sequence of nitrogen base of the coding strand of DNA in a transcription unit is:
5' - A T G A A T G - 3', the sequence of bases in its RNA transcript would be:
5' - A U G A A U G - 3'
5' - U A C U U A C - 3'
5' - C A U U C A U -3'
5' - G U A A G U A - 3'
8.
If Meselson and Stahl's experiment is continued for four generations in bacteria, the ratio of 15N/15N :15N/14N : 14N/14N containing DNA in the fourth generation would be:
1:1:0
1:4:0
0:1:3
0:1:7
9.
While analysing the DNA of an organism a total number of 5386 nucleotides were found out of which the proportion of different bases were: Adenine=29%, Guanine=17%, Cytosine=32%, Thymine=17%. Considering the Chargaffs rule it can be concluded that:
it is a double stranded circular DNA
it is single stranded DNA
it is a double stranded linear DNA
No conclusion can be drawn
10.
Which of the following are the functions of RNA?
It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides
It carries amino acids to ribosomes
It is a constituent component of ribosomes
All of the above
11.
Which was the last human chromosome to be completely sequenced:
Chromosome 1
Chromosome 11
Chromosome 21
Chromosome X
12.
Regulatory proteins are the accessory proteins that interact with RNA polymerase and affect its role in transcription. Which of the following statements is correct about regulatory protein?
They only increase expression
They only decrease expression
They interact with RNA polymerase but do not affect the expression
They can act both as activators and as repressors
13.
DNA is a polymer of nucleotides which are linked to each other by 3'-5' phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications would you choose?
(a) Replace purine with pyrimidines
(b) Remove/Replace 3' OH group in deoxyribose
(c) Remove/Replace 2' OH group with some other group in deoxyribose
(d) Both 'b' and 'c'
14.
Who amongst the following scientists had no contribution in the development of the double helix model for the structure of DNA?
Rosalind Franklin
Maurice Wilkins
Erwin Chargaff
Meselson and Stahl
15.
The human chromosomes with the highest and least number of genes in them are respectively:
chromosome 21 and Y
chromosome 1 and X
chromosome 1 and Y
chromosome X and Y
1.
(b)
5' (upstream) end and 3' (downstream) end, respectively of the transcription unit.
2.
(c)
uniform width throughout DNA
3.
(a)
The smaller ribosomal sub-unit
4.
(b)
3' - end
5.
(b)
5' - CAU -3'
6.
(c)
the structural gene and the terminators regions
7.
(a)
5' - A U G A A U G - 3'
8.
(d)
0:1:7
9.
(b)
it is single stranded DNA
10.
(d)
All of the above
11.
(a)
Chromosome 1
12.
(d)
They can act both as activators and as repressors
13.
(b)
(b) Remove/Replace 3' OH group in deoxyribose
14.
(d)
Meselson and Stahl
15.
(c)
chromosome 1 and Y
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