Iona Catholic Secondary School
Science Department
SBI - 4U1: Biology 12 University
DNA: The Molecular Basis of Life
Version B
Do Not Write on this Copy
Part A: Modified True/False
/5 marks
Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to
make the sentence or statement true.
____
1. DNA replication is described as semi-conservative because one of the strands of the new double helix is an old
strand from the parental DNA molecule, while the other has been newly synthesized using the new strand as a
template. ________________________________________
____
2. Franklin's X-ray diffraction images revealed that the structure of DNA involved a complete helical turn every 3.4
nanometers. _________________________
____
3. All the hydrogen bonds in DNA may be formed between nitrogen and hydrogen atoms and oxygen and hydrogen
atoms. _________________________
____
4. Chargaff's rules state that in DNA the totalled proportions of adenine and thymine always equal the totalled
proportions of guanine and cytosine.
________________________________________________________________________
____
5. Hammerling found that, if a stalk of Acetabularia crenulata was grafted onto the foot of A. mediterranea, a new cap
grew with characteristics intermediate to those of the two different species. However, if this cap was removed,
another grew having the characteristics of A. mediterranea. _________________________
Part A: Multiple Choice
/25 marks
Identify the letter of the choice that best completes the statement or answers the question.
____
____
____
6. Frederick Griffith discovered
a. the structure of DNA
b. transformation
c. base complementarity
d.
e.
virulence
bacterial capsules
7. In DNA, phosphodiester bonds join
a. two phosphate groups
b. bases and sugars
c. phosphate groups and sugars
d.
e.
phosphate groups and bases
two sugar molecules
8. Which of the following statements concerning Griffith's work with Streptococcus pneumoniae is incorrect?
a. injected heat-killed S-form bacteria allowed mice to survive
b. injected heat-killed S-form bacteria together with live R-form bacteria killed mice
c. injected S-form bacteria killed mice
d. injected R-form bacteria killed mice
e. the S-form bacteria are enveloped with a capsule of polysaccharide
____
9. A deoxyribose sugar molecule includes
a. 5 carbon atoms
b. 4 carbon atoms
c. 6 carbon atoms
d. 7 carbon atoms
e. 5 carbon atoms and an oxygen atom in a ring.
____
10. Isotopes are atoms of the same element
a. with the same number of protons, but different numbers of neutrons
b. with the same number of neutrons, but different numbers of protons
c. with the same numbers of protons and neutrons, but different numbers of electrons
d. with the same number of protons, but different numbers of neutrons and electrons
e. with different numbers of protons and electrons
____
11. During DNA replication, the function of RNA primers is to
a. open replication bubbles
b. serve as starting points for DNA strand elongation by DNA polymerase I in the 3' - 5' direction
c. serve as starting points for DNA strand elongation by DNA polymerase III in prokaryotes
d. prevent new-separated strands of DNA from rejoining
e. serve as a binding site for DNA ligase
____
12. The main support to the DNA molecule is provided by two backbones which run along the two sides of the double
helix. These backbones consist of
a. sugars joined by ester links
b. phosphates joined by ester links
c. sugars and phosphates linked together
d. phosphates and bases linked together
e. sugars and bases linked together
____
13. The DNA double helix makes a complete turn every
a. 0.34 nm
d.
b. 3.4 nm
e.
c. 34 nm
____
0.12 nm
12 nm
14. Hershey and Chase's experiment
a. was intended to demonstrate that the protein case of a bacteriophage remained outside a bacterial
cell after infection.
b. involved finding radioactivity inside bacteria infected with bacteriophage having DNA labelled
with 32P.
c. involved finding radioactivity inside bacteria infected with bacteriophage having DNA labelled
with 35S.
d. involved finding radioactivity inside bacteria infected with bacteriophage having protein labelled
with 32P.
e. involved finding radioactivity inside bacteria infected with bacteriophage having protein labelled
with 35S.
____
15. A DNA nucleotide contains
1. a cyclic nitrogen-containing part
2. a single ring containing five carbons
3. a part which contains four oxygen atoms surrounding a central atom.
In order, 1, 2 and 3 are
a. a base, a phosphate group, a sugar
b. a sugar, a base, a phosphate group
c. a base, a sugar, a phosphate group
d.
e.
a phosphate group, a sugar, a base
a sugar, a phosphate group, a base
____
16. The paired bases of a DNA molecule are best described as
a. covalently linked across the width of the double helix
b. identical
c. mirror images
d. complementary
e. single-stranded
____
17. During DNA replication, one of the new strands of DNA is synthesized continuously, while the other is synthesized
as a number of separate fragments of DNA that are subsequently linked by DNA ligase. This is because
a. replication starts at many points on the chromosome
b. RNA primers only anneal to one of the parental strands of DNA
c. DNA polymerase III only synthesizes DNA in the 3' - 5' direction
d. one of the parental strands is unwound slower than the other by helicase
e. DNA polymerase III only synthesizes DNA in the 5' - 3' direction
____
18. DNA is stable because hydrogen bonds are formed between
a. thymine and uracil
d. guanine and adenine
b. cytosine and thymine
e. purines and pyrimidines
c. adenine and uracil
____
19. DNA replication
a. results in each cell produced by mitosis and cytokinesis having a complete set of genetic
instructions
b. causes cytokinesis to begin
c. occurs virtually all the time during the life of a cell
d. occurs during cytokinesis
e. has different characteristics in cells producing repair tissue and those producing growth tissue
____
20. If the percentage composition of thymine in a DNA molecule is 22%, what is the percentage composition of
cytosine?
a. 28%
d. 22%
b. 32%
e. 18%
c. 26%
____
21. 5'GGCATA(X)
(Z)CCGTAT(Y)
If the above is a representation of a piece of double-stranded DNA, what symbols should occupy the positions
(X),(Y) and (Z)?
a.
b.
c.
____
3',3',5'.
5',3',3'
5',3',5'
22. In 1869, Miescher extracted nuclein from
a. slime mould
b. pus cells
c. bacterial cells
d.
e.
5',5',3'
3',5',3'
d.
e.
red blood cells
viruses
____
23. An enzyme, which excises a mismatched base in a newly synthesized strand of DNA, is called
a. a primase
d. an exonuclease
b. a excisase
e. a gyrase
c. a polymerase
____
24. The nucleotide at the end of one strand of a fragment of double-stranded DNA has a free phosphate attached to the
5' carbon of its deoxyribose sugar. The complementary nucleotide has
a. a free phosphate attached to the 3' carbon of its deoxyribose sugar
b. a hydroxyl group (-OH) attached to the 3' carbon of its deoxyribose sugar
c. a free phosphate attached to the 5' carbon of its deoxyribose sugar
d. a hydroxyl group attached to the 5' carbon of its deoxyribose sugar
e. two hydrogen atoms attached to the 3' carbon of its deoxyribose sugar
____
25. When DNA helicase is active, the result is
a. annealing of RNA primers to the DNA
b. formation of phosphodiester bonds
c. formation of hydrogen bonds
d. separation of the two strands of the double helix
e. swivelling of the single separated strands of DNA
____
26. The percentage composition of a nucleic acid molecule found in bacterial cells is
32.3% adenine
30.7% thymine
19.1% cytosine
17.9% guanine
The molecule is most likely to be
a. double-stranded DNA.
b. mitochondrial DNA.
c. messenger RNA.
____
d.
e.
double-stranded RNA.
single-stranded DNA.
27. The model for DNA structure proposed by Watson and Crick, by its very nature, suggests a way in which the DNA
molecule can replicate itself, because
a. each base is capable of specifying the base opposite to it in the double helix
b. the two strands are held together by hydrogen bonds
c. only four different bases are involved in the structure
d. hydrogen bonds only form when the strands are anti-parallel
e. each purine only forms hydrogen bonds with another purine and each pyrimidine only forms
hydrogen bonds with another pyrimidine
____
28. The number of protein-encoding genes in the human genome is approximately
a. 92 000
d. 1400
b. 102 000
e. 42 000
c. 1 500 000
____
29. Which of the following is a correct representation of a segment of DNA?
1.
2.
3.
a.
b.
c.
____
5'ATTC3'
3'ATTC5'
5'AUUC3'
3'UAAG5'
5'CCGG3'
5'GGCC3'
4.
5.
'ATAG3'
3'TATC5'
5'ACGA3'
3'TGCT5'
1
1 and 3
2 and 3
d.
e.
4 and 5
5 and 1
30. DNA replication
a. is the first step in protein synthesis
b. occurs in every living cell in a multicellular organism
c. occurs before cytokinesis
d. is only semi-conservative in eukaryotes, not prokaryotes
e. may be conservative or semi-conservative at different points in an organism's life-cycle
Part A: Matching
Match each item with the correct statement below.
a.
template strand
b.
ligase
c.
primase
d.
DNA polymerase I
e.
lagging strand
ab. replication fork
ac. semi-conservative replication
ad. Okazaki fragment
/5 marks
ae.
bc.
bd.
be.
cd.
ce.
a.
single-stranded binding proteins
leading strand
gyrase
helicase
annealing
mitosis
DNA polymerase III
____
31. new DNA strand which is synthesized continuously
____
32. short lengths of DNA produced during synthesis of lagging strand
____
33. DNA strand which directs synthesis of a complementary strand
____
34. pairing of complementary strands of DNA due to hydrogen bonding
____
35. process which results in each new DNA molecule consisting of one parental strand and one newly synthesized
strand
____
36. keep newly separated strands of DNA apart