Expression of Biological Information
EXPRESSION OF BIOLOGICAL INFORMATION
MULTIPLE CHOICE QUESTIONS
1.
To function as the heritable genetic code, DNA molecules must have all of the
following structural features EXCEPT
A. the ability to form complementary base pairs with other DNA nucleotides.
B. the ability to form complementary base pairs with RNA nucleotides
C. histone proteins associated with the double helix.
D. a sequence of nucleotides that can be decoded into a sequence of amino
acids in a protein.
2. In an analysis of the nucleotide composition of DNA to see which bases are
equivalent in concentration, which of the following would be true?
A. A = C
B. A = G and C = T
C. A + C = G + T
D. A + T = G + C
3.
Which of the following statements is NOT true about Fred Griffith’s
experiments?
A. Mice injected with smooth (S) bacteria die.
B. Mice injected with heat-killed smooth bacteria die.
C. Mice injected with heat-killed smooth bacteria and live rough (R) bacteria
die.
D. Smooth bacteria are transformed into harmless rough bacteria.
4. The diagram below shows that a normal bacteria could live in culture provided
that it is supplied with amino acid I.
Amino acid
I
Enzyme P
Amino acid
II
Enzyme Q
Enzyme R
Amino acid
III
Amino acid
IV
Enzyme S
Enzyme T
Amino acid
V
Mutant bacteria could only live in culture supplied with amino acids I, II, IV and
V. The enzyme that could not be coded by the genes of these mutant bacteria is
A. enzymes P and T.
B. enzymes R and S.
C. enzymes P, Q and T.
D. enzymes Q, R and S.
5. In Beadle and Tatum’s study of Neurospora, they were able to identify three
classes of mutants that needed arginine added to minimal media in order to grow.
Expression of Biological Information
The production of arginine includes the following steps: precursor  ornithine
citrulline  arginine. What nutrient(s) had to be supplied for the mutants with a
defective enzyme for the precursor  ornithine step to grow?
A. Precursor only.
B. Ornithine only.
C. Citrulline only
D. Ornithine or citrulline.
6. In the Meselson-Stahl experiment, bacteria were grown in a medium containing
15
N and were then transferred to a medium containing 14N. Which of the results
would be expected after two DNA replications in 14N?
A. Two newly formed DNA molecules; each consist of one radioactive
strand.
B. Two newly formed DNA molecules; each consist of two radioactive
strands.
C. Four newly formed DNA molecules; each consist of one radioactive
strand.
D. Four newly formed DNA molecules; each consist of two radioactive
strands.
7. Bacteria were grown in a medium containing 15N and were then transferred to a
medium containing 14N. After two DNA replications occurred, DNA samples
were extracted and centrifuged. The diagram below shows the expected outcome
according to the three hypotheses.
After two
DNA
replication
14
N DNA
14
N–15N DNA (Hybrid DNA)
15
N DNA
15
N DNA
I.
II.
III.
Which of the following is correctly matched?
A.
B.
C.
D.
I.
Dispersive
Conservative
Conservative
Semi-conservative
II.
Conservative
Semi-conservative
Dispersive
Dispersive
III.
Semi-conservative
Dispersive
Semi-conservative
Conservative
8. The primary function of DNA ligase is to
A. attach free nucleotides to the growing chain.
B. remove bases that might have been inserted correctly.
C. cut the two strands of the DNA molecule prior to replication.
D. seal new short stretches of nucleotides into one continuous strand.
Expression of Biological Information
9. The following events occur in the replication of DNA:
1 bonds between complementary bases break
2 bonds between complementary bases form
3 DNA molecule uncoils
4 opposite strands separate
5 sugar-phosphate bonds form
6 free nucleotides align with complementary nucleotides on each strand
In which order do these events take place?
A. 1 3
6
4
2
5
B. 3 1
4
6
2
5
C. 3 6
1
4
5
2
D. 4 3
1
6
5
2
10. The exact replication of DNA is possible due to
A. mitosis.
B. the genetic code.
C. the base-pairing rules.
D. the fact that the DNA molecules are enclosed within a nuclear envelope.
11. Which diagrams shows the pairing of an RNA nucleotide with a DNA nucleotide
transcription?
12. In transcription,
I. DNA produces messenger RNA.
II. promoters are needed so that RNA can bind to DNA.
III. a specific enzyme called RNA polymerase is required.
IV. several RNA molecules are made from the same DNA molecule
A.
B.
C.
D.
I, II, III
I, II and IV
II, III and IV
I, II, III, IV
Expression of Biological Information
13. Listed below are the stages in the cellular synthesis of a protein
1.
2.
3.
4.
5.
movement of mRNA from nucleus to cytoplasm
linking of the adjacent amino acid molecules
transcription of mRNA from a DNA template
formation of the polypeptide chain
attachment of the mRNA strand to a ribosome
In which order do these stages take place?
A. 1 3
2
5
4
B. 1 5
3
4
2
C. 3 1
5
2
4
D. 3 4
1
2
5
14. An anticodon is the sequence of the nitrogenous bases on the
A. A complementary strand of DNA which codes for one amino acid.
B. A complementary strand of mRNA which codes for one amino acid.
C. tRNA molecule at the site of attachment of the amino acid.
D. tRNA molecule which complement with appropriate sequence of bases on
mRNA.
15. The table shows the anti-codon for several tRNA which attached with a particular
kind of amino acids as given below.
Anticodon
Amino
acid
AGG AUG CGC
CGU
GCA
GCG
UAC
UCC
UGG
ser
ala
arg
arg
met
arg
thr
tyr
ala
Part of the mRNA sequence produced following transcription of the gene for a
particular polypeptide is shown.
GCA GCG UAC UCC
What is the correct sequence of amino acids produced when this mRNA is
translated?
A. ala-ala-tyr-ser
B. ala-ala-tyr-thr
C. arg-arg-met-arg
D. arg-arg-met-thr
16. Insulin is a protein containing 51 amino acids. These include 17 of the 20
different amino acids commonly occurring in proteins. What is the minimum
number of different kinds of tRNA molecules involved in the synthesis of insulin?
A. 3
B. 17
C. 20
D. 51
17. Compared with single ribosomes; polyribosomes, which are complexes of
ribosomes, increase the efficiency of protein synthesis. How is this achieved?
A. Different protein molecules can be made simultaneously.
Expression of Biological Information
B. Each copy of the mRNA molecule can be more rapidly.
C. More than one copy of the mRNA molecule can be read at the same time.
D. Many copies of the same protein can be made simultaneously from one
mRNA molecule.
18. In the lactose operon, both genes P and Q undergo the transcription process. Gene
Q can only undergo transcription with the existence of lactose and at the same
time, gene R is released from the binding of gene P product.
Which of the following is true about the genes P, Q and R?
A.
B.
C.
D.
P
Regulator gene
Structural gene
Operator gene
Promoter gene
Q
Structural gene
Operator gene
Structural gene
Regulator gene
R
Operator gene
Regulator gene
Regulator gene
Operator gene
19. Which of the following statements are true about lactose operon in the presence of
lactose?
I. The regulator gene produces an active repressor molecule.
II. Lactose binds with the repressor molecule.
III. The inactive repressor molecule binds to the promoter.
IV. The RNA polymerase binds to the operator.
V. Gene structure transcription occurs.
A.
B.
C.
D.
I, II and III
I, II and V
I, III and IV
I, II, IV and V
20. Which statement about Escherichia coli which has regulatory gene that has
undergone mutation is true?
A. Only β-galactosidase is produced.
B. Repressor produced binds with operator gene.
C. RNA polymerase is unable to bind with promoter gene.
D. E. coli produces β-galactosidase, permease and transacetylase
continuously.
Expression of Biological Information
STRUCTURED QUESTION:
1. Figure 1 show an experiment carried out by scientists to check whether their
hypothesis of DNA replication is correct. Bacteria were grown in a medium
containing 15N and were then transferred to a medium containing 14N. After DNA
replicates once, DNA samples were extracted and centrifuged. The diagram below
shows the outcome of the experiment.
After DNA
replicate once
14
N DNA
14
N–15N DNA (Hybrid DNA)
15
N DNA
15
N DNA
Tube A
Figure 1
a) Name the scientists involved in this experiment.
_________________________________________________________________
[1 mark]
b) i. According to the experiment outcome, name one hypothesis of DNA
replication that has been rejected.
_______________________________________________________________
[1 mark]
ii. Explain your answer in b (i)
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
[3 marks]
c) If the bacteria from the above experiment were transferred back to a medium
containing 15N, what result will you get?
_________________________________________________________________
[1 mark]
Expression of Biological Information
d) Name two types of enzyme involved in DNA replication and describe its
function.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
[4 marks]
2. The following diagram represents parts of a DNA molecule and a mRNA molecule.
Figure 2
a) Name molecules A, B, C and D in the spaces provided in the key.
A:
__________________________________
B:
__________________________________
C:
__________________________________
D:
__________________________________
[4 marks]
Expression of Biological Information
b) i.
What is the name given to the molecular subunit shown in the box X?
______________________________________________________________
[1 mark]
ii. According to your answer in b (i), name two component molecules which
make up the molecular subunit.
______________________________________________________________
[2 marks]
c) Condensation reactions are involved in the formation of DNA strands. Give the
names of two molecules which are linked in such a way.
__________________________________________________________________
__________________________________________________________________
[2 marks]
d) Give one piece of evidence from the diagram which indicate that the molecule Y
is RNA and not half a strand of DNA.
_________________________________________________________________
[1 mark]
3. The diagram below summarizes the process of translation.
AGA
Figure 3
Expression of Biological Information
a) Name the stage of translation process shown in the above diagram.
__________________________________________________________________
[1 mark]
b) Which is the first codon used in protein synthesis from this mRNA?
_________________________________________________________________
[1 mark]
c) What is the anti-codon sequence in tRNA 1?
_________________________________________________________________
[1 mark]
d) tRNA 1 has a 5’ – phosphate end and a 3’ – hydroxyl end. What is the function of
3’OH end in tRNA 1?
_________________________________________________________________
[1 mark]
e) Name the enzyme that catalyzes the formation of the peptide bond between amino
acids carried by tRNA 1 and tRNA 2.
________________________________________________________________________
[1 mark]
f) According to the diagram, explain what will occur to allow codon 6 to be
translated.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
[3 marks]
g) List two ways in which process I differs from process II.
_________________________________________________________________
_________________________________________________________________
[2 marks]
Expression of Biological Information
4. The diagram shows the lac operon structure in Escherichia coli.
repressor protein
substance S
Figure 4
a) Name the structures below.
R : _________________________________________
Q : _________________________________________
P : _________________________________________
[3 marks]
b) i.
Name substance S
_______________________________________________________________
[1 mark]
ii. Explain why S is important in a culture medium.
_______________________________________________________________
_______________________________________________________________
[2 marks]
c) i. Name structural gene I.
_______________________________________________________________
[1 mark]
ii. What is the enzyme encoded by your answer in c (i) and give its role.
_______________________________________________________________
_______________________________________________________________
[2 marks]
d) What will happen if substance S is absent in the medium?
_________________________________________________________________
[1 mark]
Expression of Biological Information
ESSAY QUESTIONS:
1. a) Explain the structure of DNA according to the model proposed by Watson and
Crick.
[10 marks]
b) Explain the experiment carried out by Beadle and Tatum. What did the
experiment demonstrate?
[10 marks]
2. a) Describe an experiment that proves the DNA replicates by semiconservative.
[10 marks]
b) Explain the steps involved in DNA replication process.
[10 marks]
3. a) Describe the process involved in protein synthesis in detail.
[13 marks]
b) By using the Lac operon, describe how the operon is regulated.
[7 marks]