12th biology chapter 4 MCQs (Molecular Basis of Inheritance)

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Molecular Basis of Inheritance Class 12 MCQ:


1. Griffith worked on ………….
a. Bacteriophage
b. Drosophila
c. Frog eggs
d. Streptococci
Answer : d 

ExplanationGriffith used two strains of pneumococcus (Streptococcus pneumoniae) bacteria which infect mice – a type III-S (smooth) which was virulent, and a type II-R (rough) strain which was nonvirulent.


2. The molecular knives of DNA are …………..
a. Ligases
b. Polymerases
c. Endonucleases
d. Transcriptase
Answer: c ( Endonucleases )


3. Translation occurs in the ……………
a. Nucleus
b. Cytoplasm
c. Nucleolus
d. Lysosomes
Answer: b ( Cytoplasm ) 

Explanation: In a eukaryotic cell, transcription occurs in the nucleus, and translation occurs in the cytoplasm.


4. The enzyme required for transcription is ………………
a. DNA polymerase
b. RNA polymerase
c. Restriction enzyme
d. RNAase
Answer: B


ExplanationRNA polymerase is the main transcription enzymeTranscription begins when RNA polymerase binds to a promoter sequence near the beginning of a gene (directly or through helper proteins). 


5. Transcription is the transfer of genetic information from …………..
 a. DNA to RNA
 b. tRNA to mRNA
 c. DNA to mRNA
 d. mRNA to tRNA
Answer: DNA to RNA 

6. Which of the following is NOT part of protein synthesis?
a. Replication
b. Translation
c. Transcription
d. All of these
Answer: Replication


7. In the RNA molecule, which nitrogen base is found in place of thymine?
a. Guanine
b. Cytosine
c. Thymine
d. Uracil
Answer: Uracil 


8. How many codons are needed to specify three amino acids?
a. 3
b. 6
c. 9
d. 12
Answer : 3

ExplanationAnswer and Explanation: Three codons are needed to specify three amino acidsCodons can be described as messengers that are located on the messenger RNA (mRNA). It is a sequence of three nucleotides that code for one specific amino acid; therefore, every three nucleotides represent one codon



9. Which of the following is NOT an example of an inducible operon?
a. Lactose operon
b. Histidine operon
c. Arabinose operon
d. Tryptophan operon
Answer: Tryptophan operon 

ExplanationExplanation: Lactose operon, galactose operon, and maltose operon are examples of inducible operons.



10. Place the following event of translation in the correct sequence 
i. Binding of met-tRNA to the start codon.
ii. Covalent bonding between two amino acids.
iii. Binding of the second tRNA.
iv. Joining of small and large ribosome subunits.
A. iii, iv, i, ii
B. i, iv, iii, ii
C. iv, iii, ii, i
D. ii, iii, iv, i
Answer: C

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