Introns & Exons

Q.

What are cistrons? Why are eukaryotes called monocistronic and prokaryotes polycistronic?

Q. Assertion: In bacteria the transcription and translation can be coupled.
Reason: In bacteria, transcription and translation take place in the same compartment.

1. Both assertion and reason are true and the reason is not the correct explanation of the assertion.
2. Both assertion and reason are false.
3. Assertion is true but reason is false.
4. Both assertion and reason are true and the reason is the correct explanation of the assertion.

Q. Intron is a
a. functional sequence
b. non-coding sequence
c. characteristic of prokaryotic genome
d. characteristic of eukaryotic genome

1. a, b, c, d
2. b, c, d
3. a, b, c
4. b, d

Q. Intron is a:
a. Functional sequence
b. Non-coding sequence
c. Characteristic of prokaryotic genome
d. Characteristic of eukaryotic genome

1. b, d
2. a, b, c, d
3. b, c, d
4. a, b, c

Q.

What are exons?

Q. Assertion: Primary transcript in eukaryotes is much longer than the mature mRNA.

Reason: RNA splicing helps in the removal of introns.

1. Both assertion and reason are true and the reason is the correct explanation of the assertion
2. Both assertion and reason are true but the reason is not a correct explanation of the assertion
3. The assertion is true but the reason is false
4. Both assertion and reason are false
   

Q.

What happens to exons and introns in splicing?

Q. A segment of DNA with the following sequence AGCTGACTATGAT is a template strand for RNA synthesis. What will be the complementary base sequence in the mRNA formed?

1. AGCTGACTATGAT

2. UCGACUGAUACUA
3. AGCUGACUAUGAU
4. UCGUCUGAUACUA

Q. Eukaryotic chromosomes are composed of

1. DNA + Protein
2. DNA + RNA
3. RNA + Protein
4. Only DNA

Q. In RNA splicing :

Q. Assertion :Plasmids are single stranded extrachromosomal DNA. Reason: Plasmid are usually present in eukaryotic cells.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
3. Assertion is correct but Reason is incorrect.
4. Both Assertion and Reason are incorrect.

Q.

Introns:

1. Codes for protein

2. Does not code for protein

3. Initiates transcription

4. Helps in joining pieces of RNA

Q. Assertion (A): In eukaryotes, both introns and exons are transcribed to form hnRNA.

Reason (R): The exons are removed to make the final transcript by splicing.

1. Both assertion and reason are true and reason is the correct explanation of assertion
2. Both assertion and reason are true but reason is not the correct explanation of assertion
3. Assertion is true but the reason is false
4. Both assertion and reason are false

Q. are nucleotide sequences in DNA and RNA that do not express or code for proteins.

1. Introns
2. Transposons
3. Anticodons
4. Exons

Q. The following figure represents the transcription process in eukaryotes. Identify the parts A and B and choose the correct option.
[0.7 mark]

1. A	B
   Intron	Unusual nucleotide

2. A	B
   Exon	Poly A tail

3. A	B
   Intron	Poly A tail

4. A	B
   Exon	Methyl guanosine triphosphate

Q. Intron is a:
a. Functional sequence
b. Non-coding sequence
c. Characteristic of prokaryotic genome
d. Characteristic of eukaryotic genome

1. b, d
2. a, b, c, d
3. b, c, d
4. a, b, c

Q. The nascent RNA has
(a) Exons
(b) Introns
(c) 5’ methyl guanosine triphosphate
(d) 3’ poly(A) tail
(e) Two phosphoanhydride bonds

Choose the correct option

1. A, B, C
2. A, C, E
3. A, B, E
4. All of the above

Q. RNA splicing is

1. addition of introns
   
2. removal of introns from pre mRNA to produce the final set of instructions for the protein
   
3. removal of exons from pre mRNA to produce the final set of instructions for the protein
   
4. removal of both exons and introns from pre mRNA to produce the final set of instructions for the protein
   

Q. Assertion :Polycistronic mRNA, found in prokaryotes, specify a number of polypeptides. Reason: Monocistronic mRNA, found in eukaryotes, specify only a single polypeptide.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. Assertion (A): In eukaryotes, both introns and exons are transcribed to form hnRNA.

Reason (R): The exons are removed to make the final transcript by splicing.

1. Both assertion and reason are true and reason is the correct explanation of assertion
2. Both assertion and reason are true but reason is not the correct explanation of assertion
3. Assertion is true but the reason is false
4. Both assertion and reason are false

Q. Nucleoid is the single circular strand of DNA duplex. Explain?

Q. Assertion :In prokaryotes, transcription and translation occur simultaneously, while in eukaryotes their occurrence is temporally and spatially separated. Reason: In eukaryotes, transcription occurs in nucleus and the encoded message is translated in cytoplasm, but in prokaryotes there is no demarcation between cytoplasm and nucleus having no nuclear membrane.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

Describe mRNA.

Q. Splicing represents dominance of:

1. RNA world
2. DNA world
3. Protein world
4. Virus

Q. Compare the statements A and B.
Statement A : RNA produced during transcription in eukaryotic cells cannot be straight away used in photosynthesis.
Statement B : RNA splicing phenomena helps in the removal of exons.
Select the correct description.

1. Statement A is correct and B is wrong.
2. Statement A is wrong and B is correct.
3. Both the statements A and B are wrong.
4. Both the statements A and B are correct.

Q. The following DNA sequence (5' $\to$ 3') specifies part of a protein coding sequence, starting from position 1. Which of the following mutations will give rise to a protein that is shorter than the full-length protein?

1	2	3	4	5	6	7	8	9	10	11	12	13	14	15
A	T	G	C	A	A	C	A	T	A	T	A	G	C	T

1. Deletion of nucleotide 13
2. Deletion of nucleotide 8
3. Insertion of a single nucleotide between 3 and 4
4. Insertion of a single nucleotide between 10 and 11

Q. Segments of mRNA removed during splicing are ________.

1. Introns
2. Exons
3. Promoter regions
4. Integrator regions

Q. Consider these following sentences and choose the correct ones.
I. Each gene contains a specific promoter region and a leader sequence for guiding the beginning of transcription.
II. Only one strand for DNA, called template strand is copied by RNA polymerase this strand runs in $3^{\prime }\to 5^{\prime }$ direction.
III. RNA polymerase adds complementary nucleotides forming single strand mRNA in $3^{\prime }\to 5^{\prime }$ direction.
IV. Section of DNA that has been transcribed is rewound into its original configuration.

1. II, III and IV
2. II and IV
3. I, II and IV
4. I, II, III and IV

Q. Fill in the blanks with appropriate words.
The three major types of RNA transcribed from DNA are .........., .......... and ..........

Q. Choose the right option from the statements given below.

Statement I: A monocistronic mRNA can produce several types of polypeptide chains.

Statement II: A monocistronic mRNA is usually found in eukaryotes.

Statement III: A polycistronic mRNA is usually found in prokaryotes.

Statement IV: A polycistronic mRNA can produce several types of polypeptide chains.

Statement V: A polycistronic gene is usually found in eukaryotes.