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Unit 2 Molecular Biology Practice
test 3 [67 marks]
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1.
The graph shows the effect of increasing the substrate concentration on the rate of an enzyme-catalysed reaction. What is occurring
[1 mark]
during the phase indicated by section Y of the graph?
A. The active site of the enzyme is saturated.
B. The enzyme becomes denatured.
C. The substrate concentration has risen too high.
D. The optimum rate is reached.
2.
A short sequence of nucleotides reads GGACAGAGCGCAGACGA. In which type of molecule could this sequence be found?
[1 mark]
A. DNA molecule only
B. RNA molecule only
C. Both in a DNA and an RNA molecule
D. In double-stranded DNA only
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3.
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[1 mark]
The table shows the genetic code.
Which mRNA could code for the sequence Met-Ser-Leu-Arg-Phe?
A. AUG UCA UCG UGG UUU
B. AUG UCC ACC AGA UUC
C. AUG UCU CCC AGA UUU
D. AUG UCG CUG AGG UUC
4.
[1 mark]
How does the proteome of a species contain a larger number of proteins than genes that code for these proteins?
A. Some proteins have more than one polypeptide chain.
B. There are genes that code for several proteins.
C. Not all proteins are coded for by the genome.
D. Some proteins are coded for by other proteins.
5.
A polymer of alpha-D-glucose found in plants has mostly 1,4 linkages and some 1,6 linkages. Which molecule fits this description?
[1 mark]
A. Glycogen
B. Cellulose
C. Amylose
D. Amylopectin
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6.
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In an experiment the effect of changing pH on an enzymatic reaction is tested. Which could be a dependent variable in this kind of
[1 mark]
experiment?
A. Changing substrate concentration
B. Rate of formation of product
C. Variation in temperature
D. Change in pH
7.
Meselson and Stahl conducted experiments using the isotopes 14N and 15N which showed that DNA replication is
[1 mark]
semi-conservative. What would they have observed about the distribution of isotopes in the DNA after one round of replication if DNA
replication was conservative rather than semi-conservative?
A. Only 14N DNA
B. Only 15N DNA
C. All DNA half 14N and half 15N
D. Half the DNA with only 14N and half with only 15N
8.
The most abundant structural protein in the human body is found in ligaments and skin. What is the name of this protein?
[1 mark]
A. Collagen
B. Hemoglobin
C. Myoglobin
D. Immunoglobulin
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9.
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The graph shows the changes in lactate and pyruvate measured in an athlete’s blood during and following a mild exercise period as
[1 mark]
compared to the period before the exercise.
What do these curves suggest?
A. Before the exercise, there was no pyruvate produced because there was no cell respiration.
B. During the exercise, there was not enough oxygen available for cell respiration, so the process was partly anaerobic.
C. During the exercise, the level of lactate increased due to aerobic respiration.
D. After the exercise, the level of lactate decreased because there was enough pyruvate to be used for anaerobic cell respiration.
10. What is the relative wavelength in the visible spectrum of red light and blue light and are these colours absorbed or reflected by
[1 mark]
chlorophyll?
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11. The fungus Rhytisma grows on the leaves of certain trees, causing a yellow leaf area in which chlorophyll is no longer present. A
[1 mark]
black, tar-like stain later spreads out.
What happens in the leaf when Rhytisma is present?
I. An increase in the intake of carbon dioxide
II. A reduction in the production of oxygen
III. An increase in the loss of water
A. I only
B. II only
C. II and III only
D. I, II and III
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12. The bacterium Neisseria gonorrhoeae causes infections related to the human reproductive system. The graph shows the percentage
[1 mark]
of samples in which this bacterium showed resistance to six antibiotics over a period of ten years.
What is a possible explanation for the total percentage resistance being larger than 100% in 2010?
A. People do not take the antibiotics as prescribed.
B. More people have been sampled in that year.
C. There was an epidemic of Neisseria gonorrhoeae in that year.
D. Some bacteria are resistant to more than one antibiotic.
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13. Which molecule diagram corresponds to the name?
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[1 mark]
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14. The diagram shows a cycle of reactions that occurs in human liver cells.
[1 mark]
Which term describes the overall reactions of this cycle?
A. Oxidation
B. Catabolism
C. Condensation
D. Metabolism
15. The diagram shows the structure of palmitic acid.
[1 mark]
What type of fatty acid is palmitic acid?
A. It is monounsaturated.
B. It is polyunsaturated.
C. It is saturated.
D. It is a trans-fatty acid.
16. Which are necessary to make DNA replication semi-conservative?
[1 mark]
I. Separation of the strands by RNA polymerase
II. Complementary base pairing
III. Use of a pre-existing strand as a template
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
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17. Glucose is absorbed through protein channels in the plasma membrane of epithelium cells in the small intestine. Which
[1 mark]
characteristics of glucose prevent its diffusion through the phospholipid bilayer?
A. It is non-polar and therefore hydrophobic.
B. Its hydrogen bonds link with amino acids in the protein channel.
C. It is polar and therefore hydrophilic.
D. Its covalent bonds interact with the phospholipids.
[1 mark]
18. What type of molecule is shown in this diagram?
A. Trans saturated fatty acid
B. Cis unsaturated fatty acid
C. Cis saturated fatty acid
D. Trans unsaturated fatty acid
19. A strand of mRNA consists of the following nucleotides:
[1 mark]
AUUCUGGCUA
Which of the following represents the non-transcribed (sense) strand of the DNA?
A. TAAGACCGAT
B. ATTCTGGCTA
C. UAAGACCAU
D. AUUCUGGCUA
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[1 mark]
20. What characteristic shows that this steroid molecule is a lipid?
A. It is made of carbon rings.
B. It has a very low proportion of oxygen to carbon.
C. It contains OH groups as do fatty acids.
D. It is made only of nitrogen, oxygen and hydrogen.
21a. DNA replication involves a number of enzymes including DNA polymerase. Identify one other enzyme involved in DNA replication.
21b. Explain the role of Okazaki fragments in DNA replication.
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[1 mark]
[2 marks]
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21c. The diagram below shows the process of transcription.
[1 mark]
Label the sense and antisense strands.
21d. Draw an arrow on the diagram to show where the next nucleotide will be added to the growing mRNA strand.
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[1 mark]
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22a. List two possible variants in the molecular structure of unsaturated fatty acids.
22b. State one reason to include fibre in the diet.
22c. Describe the health consequences of a diet rich in proteins.
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[1 mark]
[3 marks]
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23a. Outline, with examples, the types of carbohydrate found in living organisms.
23b. Describe the importance of hydrolysis in digestion.
23c. Explain the effect of inhibitors on the activity of enzymes.
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[4 marks]
[6 marks]
[8 marks]
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[4 marks]
24a. Distinguish between ventilation, gas exchange and cell respiration.
[6 marks]
24b. Outline the process of aerobic respiration.
24c. Respiration and other processes in cells involve enzymes. Explain the factors that can affect enzymes.
[8 marks]
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