Monday, October 1, 2012

Practice

1. The enzyme DNA polymerase can work only in
(A) 3¢ ® 5¢ direction
(B) 5¢ ® 3¢ direction
(C) Both the direction
(D) 5¢ ® 5¢ direction
Answer: (B)
2. Enzyme required for removing RNA primer during DNA replication is
(A) DNA primase
(B) DNA ligase
(C) DNA polymerase I
(D) DNA polymerase III
Answer: (C)
3. During DNA replication, the reunion or recoiling of separated DNA strand is prevented by
(A) Helix destabilizing protein
(B) Single strnad binding protein
(C) Rep protein
(D) Both (A) and (B)
Answer: (D)
4. The enzyme that cuts the bonds of DNA molecule at the origin of replication is
(A) Endonuclease
(B) DNA polymerase
(C) DNA gyrase
(D) DNA ligase
Answer: (A)
5. Which of the following enzyme is required to release the tension imposed by uncoiling of strands?
(A) Endonuclease
(B) DNA ligase
(C) DNA gyrase
(D) DNA helicase
Answer: (C)
6. The cellular composition of m-RNA is
(A) 5-10%
(B) 3-5%
(C) 10-20 %
(D) 70-80%
Answer: (B)
7. Formation of mRNA from DNA is called
(A) Transformation
(B) Transduction
(C) Traslation
(D) Transcription
Answer: (D)
8. The ratio of purines and pyrimidines in mRNA is not 1:1 because the nitrogenous bases are
(A) Unpaired
(B) Paired
(C) Paired only in loops
(D) Paired in stems
Answer: (A)
9. The codons which may present at 3¢ end of mRNA
(A) UAA
(B) UAG
(C) UGA
(D) Any one of these
Answer: (D)
10. Which of the following is not tool of genetic engineering?
(A) Vectors
(B) Enzymes
(C) Foreign DNA
(D) GMO
Answer: (D)


------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123 Email:ehab10f@gmail.com,ehababoueladab@yahoo.com ------------------------------------------
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