1.
Which of the following are connected by hydrogen bonds?
A.
Hydrogen to oxygen within a molecule of water
B.
Phosphate to sugar in a DNA molecule
C.
Base to sugar in a DNA molecule
D.
Hydrogen to oxygen between two different molecules of water
(Total 1 mark)
2.
The percentage of thymine in the DNA of an organism is approximately 30%. What is the
percentage of guanine?
A.
70%
B.
30%
C.
40%
D.
20%
(Total 1 mark)
IB Questionbank Biology
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3.
The following diagram shows a short stretch of DNA. What bases are indicated by labels Y and
Z?
Y
Z
A.
thymine
adenine
B.
thymine
guanine
C.
uracil
guanine
D.
uracil
adenine
(Total 1 mark)
IB Questionbank Biology
2
4.
Which molecules form the nucleotide marked in the diagram?
A.
phosphate, deoxyribose and nitrogenous base
B.
phosphorus, ribose and nitrogenous base
C.
phosphorus, deoxyribose and guanosine
D.
phosphate, ribose and guanine
(Total 1 mark)
IB Questionbank Biology
3
5.
The graph below shows the effect of temperature on the separation of the strands in DNA to form
single strands. The temperature at which 50% of the DNA is single-stranded is called the melting
temperature (TM).
What do the results show?
A.
When the temperature reaches 85°C there are no more double-stranded DNA molecules.
B.
When the temperature reaches 85°C the DNA strands start separating rapidly.
C.
A TM of 85°C means that DNA is not stable at room temperature (25°C).
D.
The separation of the DNA strands is directly proportional to the increase in temperature.
(Total 1 mark)
IB Questionbank Biology
4
6.
The base ratios in the DNA and RNA for an onion (Allium cepa) are given below.
Bases
A/%
G/%
C/%
T/%
DNA
31.8
18.4
18.2
31.3
Bases
A/%
G/%
C/%
U/%
RNA
24.9
29.8
24.7
20.6
What is the reason for the difference between these figures?
A.
DNA is only found in the nucleus but RNA is found throughout the cell.
B.
DNA is made entirely of double helix but RNA is not.
C.
In DNA, bases A and T are complementary but in RNA, bases A and C are complementary.
D.
RNA comes in three forms but DNA only comes in one form.
(Total 1 mark)
7.
Which enzyme catalyzes the elongation of the leading strand?
[Source: image from W K Purves, et al., (2003) Life: The Science of Biology, 4, Sinauer Associates (www.sinauer.com)
and W H Freeman (www.whfreeman.com)]
A.
RNA polymerase
B.
Helicase
C.
DNA polymerase
D.
Ligase
(Total 1 mark)
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5
8.
What is replicated by a semi-conservative process?
A.
Messenger RNA (mRNA) only
B.
Messenger RNA (mRNA) and transfer RNA (tRNA) only
C.
Messenger RNA (mRNA), transfer RNA (tRNA) and DNA only
D.
DNA only
(Total 1 mark)
9.
What sequence of processes is carried out by the structure labelled X during translation?
A.
Combining with an amino acid and then binding to an anticodon
B.
Binding to an anticodon and then combining with an amino acid
C.
Binding to a codon and then combining with an amino acid
D.
Combining with an amino acid and then binding to a codon
(Total 1 mark)
IB Questionbank Biology
6
10.
In some people, hemoglobin always contains the amino acid valine in place of a glutamic acid at
one position in the protein. What is the cause of this?
A.
An error in transcription of the hemoglobin gene
B.
An error in translation of the mRNA
C.
Lack of glutamic acid in the diet
D.
A base substitution in the hemoglobin gene
(Total 1 mark)
11.
What is a codon?
A.
A sequence of nucleotides on rRNA that corresponds to an amino acid
B.
A sequence of nucleotides on mRNA that corresponds to an amino acid
C.
A sequence of nucleotides on tRNA that corresponds to an amino acid
D.
A sequence of nucleotides on DNA that corresponds to an amino acid
(Total 1 mark)
12.
A certain gene in a bacterium codes for a polypeptide that is 120 amino acids long. How many
nucleotides are needed in the mRNA to code for this polypeptide?
A.
30
B.
40
C.
360
D.
480
(Total 1 mark)
IB Questionbank Biology
7
13.
What enzyme is used in transcription but not in translation?
A.
DNA polymerase
B.
Helicase
C.
Protease
D.
RNA polymerase
(Total 1 mark)
14.
(a)
State the type of bonds that
(i)
connect base pairs in a DNA molecule.
...........................................................................................................................
(1)
(ii)
link DNA nucleotides into a single strand.
...........................................................................................................................
(1)
(b)
Distinguish between DNA and RNA nucleotides by giving two differences in the chemical
structure of the molecules.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
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(c)
Explain the role of transfer RNA (tRNA) in the process of translation.
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
......................................................................................................................................
(2)
(Total 6 marks)
15.
Up to two additional marks are available for the construction of your answers.
(2)
(a)
Draw a labelled diagram to show how two nucleotides are joined together in a single strand
of DNA.
(3)
(b)
Outline a basic technique for gene transfer.
(6)
(c)
Explain the process of translation.
(9)
(Total 20 marks)
16.
Up to two additional marks are available for the construction of your answers.
(2)
(a)
Explain why DNA must be replicated before mitosis and the role of helicase in DNA
replication.
(4)
(b)
Explain how the base sequence of DNA is conserved during replication.
(5)
(c)
Describe the events that occur during mitosis.
(9)
(Total 20 marks)
IB Questionbank Biology
9
17.
Up to two additional marks are available for the construction of your answers.
(2)
(a)
State four elements that are needed by living organisms, other than carbon, hydrogen and
oxygen, giving one role of each.
(4)
(b)
Outline how light energy is used and how organic molecules are made in photosynthesis.
(6)
(c)
Explain the significance of complementary base pairing for replication, transcription and
translation.
(8)
(Total 20 marks)
IB Questionbank Biology
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