This practice test includes 25 important multiple-choice questions (MCQs) from the chapter - Molecular basis of inheritance (Class 12th Biology). attempt this test and revise this chapter to be fully prepared for the upcoming exam. these questions will be helpful for upcoming NEET, Aiims, and other entrance level exams.
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Q.1.
Which of the following statements is the most appropriate for sickle cell anaemia ?
- It cannot be treated with iron supplements.
- It is a molecular disease.
- It conferes resistance to acquiring malaria
- All of the above.
Answer:
(d) All of the above.
Q.2.
The first genetic material could be
- protein
- cabohydrates
- DNA
- RNA
Answer:
(d) RNA
Explanation: The first genetic material could be RNA
Explanation: The first genetic material could be RNA
Q.3.
The human chromosome 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
Answer:
(c) chromosome 1 and Y
Explanation: chromosome 1 and Y is the correct answer.
Explanation: chromosome 1 and Y is the correct answer.
Q.4.
Who amongst the following scientist had no contribution in the development of the double helix model for the structure of DN A ?
- Rosalind Franklin
- Maurice Wilkins
- Erwin Chargaff
- Meselson and Stahl
Answer:
(b) Maurice Wilkins
Explanation: Maurice Wilkins contributed in development of double helix model
Explanation: Maurice Wilkins contributed in development of double helix model
Q.5.
Which of the following steps in transcription is catalysed by RNA polymerase ?
- Initiation
- Elongation
- Termination
- All of the above
Answer:
(d) All of the above
Explanation: All of the above
Explanation: All of the above
Q.6.
Control of gene expression takes place at the level of
- DNA-replication
- transcription
- translation
- none of the above
Answer:
(b) transcription
Explanation: It takes place at the level of transcription
Explanation: It takes place at the level of transcription
Q.7.
Which was the last human chromosome to be completely sequenced ?
- Chromosome 1
- Chromosome 11
- Chromosome 21
- Chromosome X
Answer:
(d) Chromosome X
Explanation: Chromosome X was the last human chromosome to be completely sequenced
Explanation: Chromosome X was the last human chromosome to be completely sequenced
Q.8.
In some viruses, DNA is synthesised by using RNA as template. Such a DNA is called
- A – DNA
- B – DNA
- cDNA
- rDNA
Answer:
(c) cDNA
Explanation: Such a DNA is called cDNA
Explanation: Such a DNA is called cDNA
Q.9.
If the sequence of initrogen bases of the coding strand of DNA in a transcription unit is: 5’ – ATGAATG – 3’, the sequence of bases in its RNA transcript would be
- 5’ – AUG A AUG – 3’
- 5’ – UACUU AC – 3’
- 5’ – CAUUCAU – 3’
- 5’ – GUAAGUA – 3’.
Answer:
(d) 5’ – GUAAGUA – 3’.
Explanation: Sequence will be 5’ – GUAAGUA – 3’.
Explanation: Sequence will be 5’ – GUAAGUA – 3’.
Q.10.
The RNA polymerase holocnzyme transcribes
- the promoter, structural gene and the terminator region
- the promoter and the terminator region
- the structural gene and the terminator region
- the structural gene only.
Answer:
(b) the promoter and the terminator region
Explanation: The RNA polymerase holocnzyme transcribes the promoter and the terminator region
Explanation: The RNA polymerase holocnzyme transcribes the promoter and the terminator region
Q.11.
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’
Answer:
(b) 5’ – CAU – 3’
Q.12.
The amino acid attaches to the tRNA at its
- 5’- end
- 3’ – end
- anticodon site
- DHUloop.
Answer:
(b) 3’ – end
Explanation: The amino acid attaches to the tRNA at its 3’ – end
Explanation: The amino acid attaches to the tRNA at its 3’ – end
Q.13.
To initiate translation, the wiRNA first bind to
- the smaller ribosomal sub-unit
- the larger ribosomal sub-unit
- the whole ribosome
- no such specificity exists
Answer:
(a) the smaller ribosomal sub-unit
Explanation: bind to the smaller ribosomal sub-unit
Explanation: bind to the smaller ribosomal sub-unit
Q.14.
In E. colt, the lac operon gets switched on when
- lactose is present and it binds to the repressor
- repressor binds to operator
- RNA polymerase binds to the operator
- lactose is present and it binds to RNA polymerase.
Answer:
(a) lactose is present and it binds to the repressor
Explanation: In E. colt, the lac operon gets switched on when lactose is present and it binds to the repressor
Explanation: In E. colt, the lac operon gets switched on when lactose is present and it binds to the repressor
Q.15.
In DNA strand, the nucleotides are linked together by
- glycosidic bonds
- phosphodiester bonds
- peptide bonds
- hydrogen bonds
Answer:
(b) phosphodiester bonds
Explanation: In DNA strand, the nucleotides are linked together by phosphodiester bonds
Explanation: In DNA strand, the nucleotides are linked together by phosphodiester bonds
Q.16.
If a double stranded DNA has 20% of cytosine, what will be the percentage of adenine in it ?
- 20%
- 40%
- 30%
- 60%
Answer:
(c) 30%
Explanation: 30%
Explanation: 30%
Q.17.
If the sequence of bases in one strand of DNA is ATGCATGCA, what would be the sequence of bases on complementary strand ?
- ATGCATGCA
- AUGCAUGCA
- TACTACGT
- UACGUACGU
Answer:
(c) TACTACGT
Explanation: The sequence of bases on complementary strand TACTACGT
Explanation: The sequence of bases on complementary strand TACTACGT
Q.18.
How far is each base pair from the next one in DNA double helix model ?
- 2 nm
- 3.4 nm
- 34 nm
- 0.34 nm
Answer:
(d) 0.34 nm
Q.19.
Synthesis of DNA from RNA is explained by
- central dogma reverse
- reverse transcription
- feminism
- all of these
Answer:
(d) all of these
Explanation: all of these
Explanation: all of these
Q.20.
Histone proteins are
- basic, negatively charged
- basic, positively charged
- acidic, positively charged
- acidic, negatively charged
Answer:
(b) basic, positively charged
Explanation: Histone proteins are basic, positively charged
Explanation: Histone proteins are basic, positively charged
Q.21.
The structure in chromatin seen as ‘beads-on string’ when viewed under electron microscope are called
- nucleotides
- nucleosides
- histone octamer
- nucleosomes
Answer:
(d) nucleosomes
Explanation: seen as ‘beads-on string’ when viewed under electron microscope are called nucleosomes
Explanation: seen as ‘beads-on string’ when viewed under electron microscope are called nucleosomes
Q.22.
Find out the wrong statement about heterochromatin,
- It is densely packed
- It stains dark
- It is transcriptionally active.
- It is late replicating
Answer:
(c) It is transcriptionally active.
Q.23.
They year 2003 was celebrated as the 50th anniversary of discovery of
- transposons by Barbare Me Clintock
- structure of DNA by Watson and Crick
- Mendel’s laws of inheritance
- biotechnology by Kary Muliis.
Answer:
(b) structure of DNA by Watson and Crick
Explanation: They year 2003 was celebrated as the 50th anniversary of discovery of structure of DNA by Watson and Crick
Explanation: They year 2003 was celebrated as the 50th anniversary of discovery of structure of DNA by Watson and Crick
Q.24.
Amino acids which are specified by single codons are
- phenylalanine and arginine
- tryptophan and methionine
- valine and proline
- methionine and aroinine
Answer:
(b) tryptophan and methionine
Explanation: Amino acids which are specified by single codons are tryptophan and methionine
Explanation: Amino acids which are specified by single codons are tryptophan and methionine
Q.25.
Which out of the following statements is incorrect ?
- Genetic code is ambiguous.
- Genetic code is deqenerate
- Genetic code is universal
- Genetic code is non-overlanning.
Answer:
(a) Genetic code is ambiguous.
Explanation: Genetic code is ambiguous is incorrect.
Explanation: Genetic code is ambiguous is incorrect.
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