Q.1-The monomeric deoxyribonucleotide units of DNA include all except-
Q.2- The two strands of this double-stranded helix are held in register by-
A) Hydrogen bonds between the purine and pyrimidine bases of the respective linear molecules
B) Van der Waals forces between the stacked adjacent base pairs
C) Hydrophobic interactions between the stacked adjacent base pairs
D) All of the above
E) None of the above.
Q.3- Chargaff’s rule states that in a double stranded DNA molecule-
A) Concentration of Deoxyadenosine (A) nucleotides equals that of Thymidine (T) nucleotides
B) Concentration of Deoxyadenosine (A) nucleotides equals that of Deoxy guanosine (G) nucleotides
C) Concentration of Deoxy cytidine (C) nucleotides equals that of Thymidine (T) nucleotides
D) Concentration of Deoxy uridine (U) nucleotides equals that of Deoxy guanosine (G) nucleotides.
E) All of the above.
Q.4- Choose the incorrect statement out of the following:
A) Double-stranded DNA exists in at least six forms (A–E and Z)
B) The B form is usually found under physiologic conditions
C) Single turn of B-DNA about the axis of the molecule contains six base pairs
D) The distance spanned by one turn of B-DNA is 3.4 nm
E) The width (helical diameter) of the double helix in B-DNA is 2 nm.
Q.5- When the DNA molecule is twisted in the direction opposite from the clockwise turns of the right-handed double helix found in B-DNA, such DNA is said to have acquired-
A) Z form
B) A form
C) Positive supercoils
D) Negative supercoils
E) No change.
Q.6- Choose the correct statement out of the following:
A) The common form of DNA is said to be Left-handed
B) The coding strand is copied during RNA synthesis
C) The two strands of the double-helical DNA molecule run parallel to each other
D) Template strand matches the sequence of the RNA transcript
E) The G–C bonds are much more resistant to denaturation than A–T-rich regions.
Q.7- Ribonucleic acid (RNA) is a polymer of purine and pyrimidine ribonucleotides linked together by-
A) Hydrogen bonds
B) Hydrophobic interactions
C) Vander wal’s forces
D) 3’-5’ Phosphodiester linkages
E) 5’-3’ Phosphodiester linkages
Q.8- Which of the following types of RNA participate in RNA processing?
C) Small nuclear RNA (snRNA)
D) Small Interfering RNAs (siRNAs)
E) Heterogeneous nuclear RNA (hnRNA)
Q.9- The anticodon region is an important structural component of-
C) r- RNA
E) Micro RNAs
Q.10- The Small Nuclear RNAs (snRNAs) are rich in-
Q.11- The Z DNA helix:
A) Has fewer base pairs per turn than the B DNA
B) Has alternating GC sequences
C) Tends to be found at the 3’ end of genes
D) Is inhibited by methylation of the bases
E) Is a permanent conformation of DNA
Q.12- An endonuclease is an enzyme that hydrolyzes:
A) A nucleotide from only the 3’ end of an oligonucleotide
B) A nucleotide from either terminal of an oligonucleotide
C) A phosphodiester bond located in the interior of a polynucleotide
D) A bond only in the specific sequence of nucleotides
E) A nucleotide from only the 5’end of an oligonucleotide
Q.13- Which of the following has the highest percentage of modified bases ?
A) hn RNA
C) sn RNA
Q.14- Which of the following RNAs contains both a 7-Methyl guanosine triphosphate cap and polyadenylate segment?
A) hn RNA
C) sn RNA
E) r- RNA
Q.15- Choose the incorrect statement about an RNA:
A) Has a single stranded structure
B) Does not obey Chargaff’s rule
C) Does not exhibit Watson and crick’s base pairing
D) Instead of Uracil contains the ribonucleotides of thymine
E) The sugar moiety is ribose
Q.16- Choose the incorrect statement about histones
A) H1 histones are tightly bound to chromatin
B) H2A, H2B, H3, and H4 form the core of a nucleosome
C) H3 and H4 form a tetramer
D) H2A and H2B form dimers
E) Histone oligomers associate to form the histone octamer
Q.17- When the B DNA is slightly dehydrated in the laboratory it takes on-
A) Negative supercoils
B) Positive supercoils
C) Z conformation
D) A conformation
E) Remains unchanged in conformation
Q.18- Which of the following nucleic acids has a left-handed helix?
C) B DNA
Q.19- Which of the following statements is incorrect about t RNA species?
A) They have the smallest size of the three major species
B) All t RNAs have between 10-20 nucleotides
C) There is at least one specific t RNA molecule for each of the 20 amino acids
D) They make up 15% of the t RNA in the cell.
E) t RNA molecules contain unusual bases.
Q.20- Which of the following processes would not lead to disruption of the nucleosomal structure?
Key to answers
1)-D, 2)- D, 3)- A, 4)- C,5)- D, 6)- E, 7)- D, 8)- C, 9)- D, 10)- A, 11)- B, 12)- C, 13)- B, 14)- D, 15)- D, 16)- A, 17)- D, 18)- A, 19)- B, 20)- B.Please help "Biochemistry for Medics" by CLICKING ON THE ADVERTISEMENTS above!