1

1.
A DNA molecule contained 8000 nucleotides of which 20% contained adenine
How many nucleotides would have contained guanine?
A.
1600
B.
2400
C.
3200
D.
4800
2.
The percentage of adenine bases in a double strand of DNA is known. For how many of the other bases could the percentage be calculated?
A.
None
B.
One
C.
Two
D.
Three
4.
A fragment of DNA was found to have
60 guanine bases and 30 adenine bases.
3.
If 10% of the bases in a molecule of DNA are adenine, what is the ratio of adenine to guanine in the same molecule? What is the total number of deoxyribose sugar molecules in this fragment?
A.
30
B.
45
C.
90
A.
1:1
B.
1:2
C.
1:3
D.
1:4
D.
180
5.
(a) Decide if each of the statements relating to DNA in the table below is true or false and tick the appropriate box.
If you decide that the statement is false, write the correct term in the correction box to replace the term underlined in the statement.
True False Correction Statement
A chromosome is made up of DNA associated with proteins.
DNA has a doublestranded parallel structure.
One strand of DNA has deoxyribose at the 3’ end of one strand and a base at the 5’ end.
(2)
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(b) A section of a DNA molecule containing a total of 1600 bases has 184 adenine and 216 thymine bases on one strand. The complementary strand contains 268 cytosine bases.
(i) Calculate the number of adenine bases in this whole section of the DNA molecule.
Space for calculation
______________________ (1)
(ii) Calculate the number of guanine bases in the complementary strand.
Space for calculation
_______________________(1)
6.
The diagram below represents the four different nucleotides of DNA.
The bases of the nucleotides are bonded in pairs.
(i) Name the type of bond which links the base of one nucleotide to the base of another.
(ii) On the diagram:
1.
Insert the appropriate letters or names of the four different nucleotides. (1)
2.
Draw lines to show how adjacent nucleotides are bonded in a DNA molecule. (1)
3.
Add the positions of the 3’ and 5’ carbons to both strands. (1)
3

7.
The genetic material in the mitochondria of eukaryotic cells is found in
A.
Linear chromosomes
B.
Circular plasmids
C.
Circular chromosomes
D.
Inner membranes
8.
Which line in the table below shows correctly the organisation of DNA in the cells or organelles given?
Cell or organelle
A Prokaryotic cell
B Eukaryotic cell
C mitochondrion
D chloroplast
Organisation of DNA
Circular chromosomes
Plasmid absent present present present present absent absent absent
1.
The diagram shows DNA during replication. Base H represents thymine and base M represents guanine. Which letters represent the base cytosine?
E.
J and K
F.
J and L
G.
N and P
H.
N and R
2.
The diagram shows part of a DNA molecule during replication. Bases are represented by numbers and letters.
If 1 represents adenine and 3 represents cytosine, which line in the table identifies correctly the bases represented by the letters
N, P, Q and R?
N P Q R
A guanine cytosine guanine thymine
B cytosine guanine cytosine adenine
C guanine cytosine cytosine adenine
D cytosine guanine guanine adenine
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3. The diagram below shows part of a DNA molecule during replication and other molecules are associated with it.
(a) Name molecule X which is associated with the tightly coiled DNA.
________________________________________________________________ (1)
(b) Name the type of bond shown at Y.
________________________________________________________________ (1)
(c) Name base Z.
________________________________________________________________ (1)
(d) Underline one word in each pair to make the sentence correct.
(1)
(e) State the role of DNA polymerase in the process of DNA replication.
__________________________________________________________________________
__________________________________________________________________________ (1)
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4 (a) Decide if each of the statements relating to DNA replication is true or false and tick the appropriate box.
If you decide that the statement is false, write the correct term in the correction box to replace the term underlined in the statement.
Statement
During DNA replication hydrogen bonds between bases break.
During the formation of a new DNA molecule, base pairing is followed by bonding between deoxyribose and bases.
As a result of DNA replication the
DNA content of a cell is halved.
True False Correction
(b)Free DNA nucleotides are needed for DNA replication.
Name one other substance that is needed for DNA replication.
(2)
___________________________________ (1)
(c) A single strand of a DNA molecule has 6000 nucleotides of which 24% are adenine and
18% are cytosine.
(i) Calculate the combined percentage of thymine and guanine bases on the same
DNA strand.
(ii)
Space for calculation
________________ % (1)
How many guanine bases would be present on the complementary strand of this
DNA molecule?
Space for calculation
__________________ bases (1)
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5. (a)The replication of part of a DNA molecule is represented in the diagram.
(i) Name the nucleotide component R and the base S.
R ___________________________
S ___________________________
(ii) Name the type of bond labelled X.
X ___________________________
(b) Explain why DNA replication must take place before a cell divides
________________________________________________________________________________
________________________________________________________________________________
_____________________________________________________________________________ (1)
(1)
(1)
(1)
6.
During DNA replication one of the strands of DNA (the lagging strand) is replicated as a series of fragments that are then bonded together. The enzymes that make and bond the DNA fragments are
A.
polymerase and ligase
B.
ligase and kinase
C.
polymerase and nuclease
D.
kinase and nuclease
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7. The diagram below shows a small part of a DNA molecule during replication.
(a) Name the short sequence of bases X needed to start DNA replication.
___________________________________
(b) Name the enzyme responsible for joining DNA fragments together during replications
______________________________________________________________
8. The polymerase chain reaction (PCR) is used to
A. join DNA fragments
B. cut open plasmid DNA
C. amplify DNA
D. extract DNA from cells
(1)
(1)
9. Which of the following stages in the polymerase chain reaction (PCR) is carried out at
95⁰C?
A. annealing of primers
B. separation of DNA strands
C. formation of phosphodiester bonds
D. complementary base pairing
10. The graph below shows the temperature changes involved in one cycle of the polymerase chain reaction (PCR)
11. The role of the polymerase chain reaction
(PCR) is to
A. profile DNA
B. anneal DNA
C. replicate DNA
D. sequence DNA
Which letter indicated when primers would bind to target sequences of DNA?
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12. The polymerase chain reaction (PCR) amplifies specific sequences of DNA in vitro. The flow chart below shows how a sample of DNA was treated during a cycle of the PCR procedure.
(a) Describe the effect of heating the DNA at stage 1.
__________________________________________________________________________
________________________________________________________________________ (1)
(b) Give the reason for decreasing the temperature to 55⁰C at stage 2
_________________________________________________________________________
_______________________________________________________________________ (1)
(c) Name the enzyme used to replicate DNA.
_____________________________________________________ (1)
(d) State the role of primers in DNA replication during PCR and explain why two different primers are needed.
Role_______________________________________________________________________
__________________________________________________________________________ (1)
Explanation ________________________________________________________________
__________________________________________________________________________
___________________________________________________________________________(1)
(e) The number of DNA molecules doubles each cycle of the PCR procedure.
Calculate the number of cycles needed to produce 128 copies of a single DNA molecule.
Space for calculation
_______________________ cycles (1)
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(f) The diagram below shows the contents of a tube used in a PCR procedure.
Describe the contents of a suitable control tube designed to show that DNA is needed in a PCR reaction.
__________________________________________________________________________
________________________________________________________________________ (1)
13. A short stretch of a DNA molecule that could be used as a template for the polymerase chain reaction(PCR) is shown below.
5’ ATTCCGGTCGACCGGTAC 3’ (top strand)
3’ TAAGGCCAGCTGGCCATG 5’ (bottom strand)
Which of the following correctly represents the base sequence of a primer that would bind to the top strand of the template DNA?
A. 5’ TGGCCTTA 3’
B. 5’ ATTCCGGT 3’
C. 5’ACCGGAAT 3’
D. 5’ TAAGGCCA 3’
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