Take The Hardest Chemistry Practice Test! Quiz
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- 1.
From the assigned reading in Todar’s online book of Bacteriology, microbes impact human lives and the environment in many ways however, the most significant impact of microorganisms on earth is the ability to recycle the primary elements found in all living things. These primary elements are oxygen, as well as _______ and __________.
- A.
Sulfur
- B.
Nitrogen
- C.
Oxygen
- D.
Carbon
- E.
B and D
Correct Answer
E. B and DExplanation
Microorganisms have the ability to recycle the primary elements found in all living things, including oxygen, sulfur, nitrogen, and carbon. Oxygen is essential for the survival of all living organisms. Sulfur is an important element for various biological processes, including the synthesis of certain amino acids. Nitrogen is a crucial component of proteins and nucleic acids. Carbon is the building block of organic molecules and is essential for life. Therefore, the correct answer is B and D, which includes sulfur and nitrogen.Rate this question:
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- 2.
Primary producers are those microorganisms (such as cyanobacteria) that through photosynthesis take in _____ out of the atmosphere and convert it to organic (cellular) material, and as a result of carbon fixation reactions release _____ into the atmosphere.
- A.
CO
- B.
CO2
- C.
CH4
- D.
O2
- E.
B and D
Correct Answer
E. B and DExplanation
Primary producers, such as cyanobacteria, take in carbon dioxide (CO2) from the atmosphere through photosynthesis and convert it into organic material. This process is known as carbon fixation. As a result of carbon fixation reactions, oxygen (O2) is released into the atmosphere. Therefore, the correct answer is B and D, which represents both CO2 and O2.Rate this question:
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- 3.
Nitrogen gas (N2) in the atmosphere is not in a usable form for plants on earth, the nitrogen gas must be converted to the usable form of ammonia (NH3) by microorganisms living free and in symbiotic relationships with plants. This process is called _______________
- A.
Sulfur fixation
- B.
Carbon fixation
- C.
Nitrogen fixation
- D.
None of the above
Correct Answer
C. Nitrogen fixationExplanation
Nitrogen gas (N2) in the atmosphere cannot be directly utilized by plants. It needs to be converted into a usable form, which is ammonia (NH3), in order for plants to use it for their growth and development. This conversion process is known as nitrogen fixation. Microorganisms, both free-living and in symbiotic relationships with plants, play a crucial role in this process by converting atmospheric nitrogen into ammonia, which can then be absorbed by plants. Sulfur fixation and carbon fixation are unrelated processes, and therefore, they are not the correct answers.Rate this question:
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- 4.
Which of the following pairs is mismatched?
- A.
Ehrlich - Chemotherapy
- B.
Koch - Aseptic Surgery
- C.
Pasteur - Proof of biogenesis
- D.
Jenner- Vaccination
Correct Answer
B. Koch - Aseptic SurgeryExplanation
The given pair "Koch - Aseptic Surgery" is mismatched. Robert Koch is known for his contributions to microbiology, particularly his work on the identification and isolation of disease-causing bacteria. He developed techniques for pure culture isolation and staining bacteria, which helped in the identification of specific bacteria causing diseases. On the other hand, aseptic surgery refers to surgical techniques and practices aimed at preventing the introduction of microorganisms into the surgical site, which is not directly related to Koch's work.Rate this question:
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- 5.
Which of the following is a scientific name?
- A.
IGAS
- B.
Flesh eating bacteria
- C.
Group A streptococcus
- D.
Streptococcus pyogenes
- E.
Streptococci
Correct Answer
D. Streptococcus pyogenesExplanation
Streptococcus pyogenes is a scientific name because it follows the binomial nomenclature system used in scientific classification. It consists of the genus name "Streptococcus" and the species name "pyogenes." This naming convention helps to identify and classify organisms accurately and universally. On the other hand, IGAS, Flesh eating bacteria, Group A streptococcus, and Streptococci are not scientific names as they do not follow the proper naming conventions used in scientific taxonomy.Rate this question:
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- 6.
Which of the following is NOT a domain in the three-domain system?
- A.
Animalia
- B.
Archaea
- C.
Bacteria
- D.
Eukarya
Correct Answer
A. AnimaliaExplanation
Animalia is not a domain in the three-domain system because the three-domain system categorizes organisms into three domains based on their cellular structure, specifically the type of cells they have. The three domains are Archaea, Bacteria, and Eukarya. Animalia is a kingdom within the domain Eukarya, but it is not a separate domain itself.Rate this question:
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- 7.
Which of the following statements about fungi is true?
- A.
All are prokaryotic
- B.
All are multicellular
- C.
All require organic material for growth
- D.
All grow using sunlight and carbon dioxide
- E.
All are plants
Correct Answer
C. All require organic material for growthExplanation
Fungi are heterotrophic organisms that obtain their nutrients by breaking down organic material. They cannot produce their own food through photosynthesis like plants do, so they rely on organic matter for growth. This is why the statement "All require organic material for growth" is true for fungi.Rate this question:
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- 8.
Which of the following statements about protozoa is false?
- A.
They have rigid cell walls
- B.
They are classified by their method of locomotion
- C.
All are unicellular
- D.
All have complex cells
- E.
All are eukaryotic
Correct Answer
A. They have rigid cell wallsExplanation
The statement "They have rigid cell walls" is false because protozoa do not have rigid cell walls. Instead, they have flexible cell membranes that allow them to change shape and move. Protozoa are classified by their method of locomotion, are unicellular, have complex cells, and are eukaryotic.Rate this question:
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- 9.
Which of the following statements about viruses is false?
- A.
Acellular
- B.
Does not metabolize nutrients
- C.
Use host cell metabolic machinery to reproduce genome
- D.
Viruses have both DNA and RNA together as the genetic material
- E.
Viruses are parasitic
Correct Answer
D. Viruses have both DNA and RNA together as the genetic materialExplanation
The statement that viruses have both DNA and RNA together as the genetic material is false. Viruses can have either DNA or RNA as their genetic material, but not both at the same time. Some viruses have DNA as their genetic material, while others have RNA.Rate this question:
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- 10.
Microbes are important in maintaining Earth’s ecological balance as well as
- A.
Maintaining good health in bacteria
- B.
Maintaining good health in humans and animals
- C.
Used to produce food and chemicals that are utilized by humans
- D.
Cause disease as a result of colonization
- E.
B, C, and D
Correct Answer
E. B, C, and DExplanation
Microbes play a crucial role in maintaining Earth's ecological balance as they are involved in various processes such as nutrient cycling and decomposition. They also contribute to maintaining good health in bacteria, humans, and animals by aiding in digestion, producing essential vitamins, and supporting the immune system. Additionally, microbes are used in the production of food and chemicals that are utilized by humans. However, some microbes can also cause disease when they colonize and multiply in the body. Therefore, the correct answer is B, C, and D.Rate this question:
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- 11.
Which of the following compounds is NOT an enzyme?
- A.
Dehydrogenase
- B.
Cellulase
- C.
Coenzyme A
- D.
B-galactosidase
- E.
Sucrase
Correct Answer
C. Coenzyme AExplanation
Coenzyme A is not an enzyme but rather a coenzyme. Coenzymes are organic molecules that assist enzymes in carrying out their functions. They often act as carriers of specific functional groups or help in the transfer of chemical groups between enzymes. In the case of Coenzyme A, it plays a crucial role in various metabolic reactions by carrying and transferring acetyl groups. While enzymes catalyze chemical reactions, coenzymes like Coenzyme A assist enzymes in their catalytic functions.Rate this question:
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- 12.
Which organism is NOT correctly matched to its energy source?
- A.
Photoheterotroph - Light
- B.
Photoautotroph - CO2
- C.
Chemoautotroph - Fe2+
- D.
Chemoheterotroph - Glucose
- E.
Chemoautotroph - NH3
Correct Answer
B. pHotoautotropH - CO2Explanation
The correct answer is "Photoautotroph - CO2" because photoautotrophs are organisms that can produce their own food using light energy, and CO2 is the source of carbon that they use to synthesize organic compounds through photosynthesis.Rate this question:
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- 13.
Which of the following statements about anaerobic respiration is false?
- A.
It involves glycolysis only
- B.
It involves the Krebs cycle.
- C.
It involves the reduction of nitrate.
- D.
It generates ATP.
- E.
It requires cytochromes.
Correct Answer
A. It involves glycolysis onlyExplanation
Anaerobic respiration involves the reduction of nitrate, which is the process of using nitrate as a final electron acceptor instead of oxygen. This process occurs in certain bacteria and archaea. Therefore, the statement "It involves glycolysis only" is false because anaerobic respiration also involves the reduction of nitrate.Rate this question:
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- 14.
What type of reaction is in Figure 5.2?
- A.
Decarboxylation
- B.
Transamination
- C.
Dehydrogenation
- D.
Oxidation
- E.
Reduction
Correct Answer
B. TransaminationExplanation
The reaction in Figure 5.2 is most likely a transamination reaction. Transamination is a type of reaction where an amino group is transferred from one molecule to another, typically from an amino acid to a keto acid. This reaction is commonly involved in the synthesis and breakdown of amino acids.Rate this question:
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- 15.
What is the fate of pyruvic acid in an organism that uses aerobic respiration?
- A.
It is reduced to lactic acid.
- B.
It is oxidized in the Krebs cycle
- C.
It is oxidized in the electron transport chain.
- D.
It is catabolized in glycolysis.
- E.
It is reduced in the Krebs cycle.
Correct Answer
B. It is oxidized in the Krebs cycleExplanation
Pyruvic acid is a product of glycolysis, the initial step of cellular respiration. In organisms that use aerobic respiration, pyruvic acid is further oxidized in the Krebs cycle, also known as the citric acid cycle or tricarboxylic acid cycle. In this cycle, pyruvic acid undergoes a series of reactions that result in the release of carbon dioxide and the production of energy-rich molecules such as ATP and NADH. Therefore, the correct answer is that pyruvic acid is oxidized in the Krebs cycle.Rate this question:
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- 16.
How would a noncompetitive inhibitor interfere with a reaction involving the enzyme shown in Figure 5.3?
- A.
It would bind to a.
- B.
It would bind to b.
- C.
It would bind to c.
- D.
It would bind to d.
- E.
Can't tell
Correct Answer
B. It would bind to b.Explanation
A noncompetitive inhibitor would bind to a site on the enzyme other than the active site, known as the allosteric site. This binding would cause a conformational change in the enzyme, altering its shape and reducing its activity. As a result, the reaction involving the enzyme shown in Figure 5.3 would be interfered with, leading to a decrease in the rate of the reaction.Rate this question:
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- 17.
How is ATP generated in the reaction shown in Figure 5.4?
- A.
Glycolysis
- B.
Fermentation
- C.
Photophosphorylation
- D.
Oxidative phosphorylation
- E.
Substrate-level phosphoorylation
Correct Answer
E. Substrate-level pHospHoorylationExplanation
Substrate-level phosphorylation is the process in which ATP is generated by transferring a phosphate group from a high-energy substrate directly to ADP. In this reaction, the energy released from the substrate is used to form ATP. This process occurs in glycolysis, where glucose is broken down into pyruvate, and in the citric acid cycle, where acetyl CoA is oxidized to produce ATP. Unlike oxidative phosphorylation, which occurs in the electron transport chain and requires oxygen, substrate-level phosphorylation does not require oxygen and can occur in the absence of it.Rate this question:
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- 18.
Which of the following is the best definition of oxidative phosphorylation?
- A.
Electrons are passed through a series of carriers to O2.
- B.
The energy released as carrier molecules are oxidized is used to generate ATP
- C.
The energy released in the reduction of carrier molecules is used to generate ATP.
- D.
The transfer of a high-energy phosphate group to ADP.
Correct Answer
B. The energy released as carrier molecules are oxidized is used to generate ATPExplanation
Oxidative phosphorylation is the process in which electrons are passed through a series of carriers to O2. As the carrier molecules are oxidized, energy is released, and this energy is utilized to generate ATP. This is the best definition because it accurately describes the key steps and energy conversion involved in oxidative phosphorylation.Rate this question:
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- 19.
Which of the following statements about substrate-level phosphorylation is false?
- A.
It involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP.
- B.
No final electron acceptor is required.
- C.
It occurs in glycolysis.
- D.
The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.
- E.
It occurs in the Krebs cycle.
Correct Answer
D. The oxidation of intermediate metabolic compounds releases energy that is used to generate ATP.Explanation
Substrate-level phosphorylation involves the direct transfer of a high-energy phosphate group from an intermediate metabolic compound to ADP. It occurs in glycolysis and the Krebs cycle. No final electron acceptor is required for substrate-level phosphorylation. However, the oxidation of intermediate metabolic compounds does not release energy that is used to generate ATP. This statement is false because the oxidation of these compounds actually releases energy that is used to drive other cellular processes.Rate this question:
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- 20.
Which of the following statements about photophosphorylation is false?
- A.
Light liberates an electron from chlorophyll.
- B.
The oxidation of carrier molecules releases energy.
- C.
Energy from oxidation reactions is used to generate ATP from ADP.
- D.
It requires CO2.
- E.
It occurs in photosynthesizing cells.
Correct Answer
D. It requires CO2.Explanation
Photophosphorylation is the process by which light energy is used to generate ATP in photosynthesizing cells. It involves the liberation of an electron from chlorophyll by light, the oxidation of carrier molecules to release energy, and the use of this energy to generate ATP from ADP. However, photophosphorylation does not require CO2. CO2 is involved in the Calvin cycle, which is a separate process that occurs during photosynthesis. Therefore, the statement "It requires CO2" is false.Rate this question:
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- 21.
A gene is best defined as
- A.
A segment of DNA.
- B.
Three nucleotides that code for an amino acid.
- C.
A sequence of nucleotides in DNA that codes for a fuctional product
- D.
A sequence of nucleotides in RNA that codes for a functional product.
- E.
A transcribed unit of DNA.
Correct Answer
C. A sequence of nucleotides in DNA that codes for a fuctional productExplanation
A gene is best defined as a sequence of nucleotides in DNA that codes for a functional product. This definition encompasses the fact that genes are specific sequences of DNA that contain the instructions for creating functional products, such as proteins or RNA molecules. Genes are responsible for the expression of traits and play a crucial role in the functioning of living organisms.Rate this question:
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- 22.
Which of the following pairs is mismatched?
- A.
DNA polymerase – makes a molecule of DNA from a DNA template
- B.
RNA polymerase – makes a molecule of RNA from an RNA template
- C.
DNA ligase – joins segments of DNA
- D.
Transposase – insertion of DNA segments into DNA
- E.
DNA gyrase – coils and twists DNA
Correct Answer
B. RNA polymerase – makes a molecule of RNA from an RNA templateExplanation
RNA polymerase is responsible for making a molecule of RNA from a DNA template, not an RNA template. This process is known as transcription, where the DNA sequence is copied into an RNA molecule. Therefore, the pair "RNA polymerase – makes a molecule of RNA from an RNA template" is mismatched.Rate this question:
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- 23.
Which of the following statements is false?
- A.
DNA polymerase joins nucleotides in one direction only.
- B.
The leading strand of DNA is made continuously.
- C.
The lagging strand of DNA is started by an RNA primer.
- D.
DNA replication proceeds in one direction around the bacterial chromosome.
- E.
Multiple replication forks are possible on a bacterial chromosome.
Correct Answer
D. DNA replication proceeds in one direction around the bacterial chromosome.Explanation
DNA replication does not proceed in one direction around the bacterial chromosome. Instead, it occurs bidirectionally from a replication origin. Two replication forks are formed, and DNA synthesis proceeds in both directions away from the origin. This allows for the simultaneous replication of both the leading and lagging strands of DNA. Therefore, the statement that DNA replication proceeds in one direction around the bacterial chromosome is false.Rate this question:
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- 24.
DNA is constructed of
- A.
A single strand of nucleotides with internal hydrogen bonding.
- B.
Nucleotides bonded A–C and G–T.
- C.
Two strands of nucleotides running antiparallel.
- D.
Two strands of identical nucleotides with hydrogen bonds between them.
Correct Answer
C. Two strands of nucleotides running antiparallel.Explanation
DNA is constructed of two strands of nucleotides running antiparallel. This means that the two strands run in opposite directions, with one strand running in the 5' to 3' direction and the other running in the 3' to 5' direction. The nucleotides in each strand are bonded together by hydrogen bonds. This antiparallel arrangement allows for the complementary base pairing between adenine (A) and thymine (T), as well as between cytosine (C) and guanine (G). This structure is essential for DNA replication and the transmission of genetic information.Rate this question:
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- 25.
Which of the following is NOT a product of transcription?
- A.
A new strand of DNA
- B.
RRNA
- C.
TRNA
- D.
MRNA
- E.
None of the above
Correct Answer
A. A new strand of DNAExplanation
A new strand of DNA is not a product of transcription. Transcription is the process in which the DNA sequence is used as a template to synthesize mRNA. mRNA is the product of transcription and carries the genetic information from the DNA to the ribosomes for protein synthesis. rRNA and tRNA are also products of transcription, as they are involved in protein synthesis. However, a new strand of DNA is synthesized during DNA replication, not transcription.Rate this question:
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- 26.
Which of the following statements about bacteriocins is false?
- A.
The genes coding for them are on plasmids.
- B.
They cause food-poisoning symptoms.
- C.
Nisin is a bacteriocin used as a food preservative.
- D.
They can be used to identify certain bacteria.
- E.
Bacteriocins kill baceria.
Correct Answer
B. They cause food-poisoning symptoms.Explanation
Bacteriocins are antimicrobial peptides or proteins produced by bacteria to kill or inhibit the growth of other bacteria. The genes coding for bacteriocins are often found on plasmids, which are small, circular DNA molecules separate from the bacterial chromosome. Nisin is a well-known bacteriocin that is commonly used as a food preservative due to its antimicrobial properties. Bacteriocins can indeed be used to identify certain bacteria, as different bacteria produce different types of bacteriocins. However, it is false to say that bacteriocins cause food-poisoning symptoms. Bacteriocins specifically target other bacteria and are not toxic to humans or animals.Rate this question:
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- 27.
In Figure 8.1, which colonies are streptomycin-resistant and leucine-requiring?
- A.
1, 2, 3, and 9
- B.
3 and 9
- C.
4, 6, and 8
- D.
4 and 8
- E.
5 and 6
Correct Answer
D. 4 and 8Explanation
The colonies that are streptomycin-resistant and leucine-requiring in Figure 8.1 are colonies 4 and 8.Rate this question:
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- 28.
Table 8.1 Culture 1: F+, leucine+, histidine+ Culture 2: F-, leucine-, histidine- In Table 8.1, what will be the result of conjugation between cultures 1 and 2?
- A.
1 will remain the same; 2 will become F+, leucine-, histidine-
- B.
1 will become F-, leu+, his+; 2 will become F+, leu-, his-
- C.
1 will become F-, leu-, his-; 2 will remain the same
- D.
1 will remain the same; 2 will become F+, leu+, his+
- E.
1 will remain the same; 2 will become F+ and recombination may occur
Correct Answer
A. 1 will remain the same; 2 will become F+, leucine-, histidine-Explanation
The result of conjugation between cultures 1 and 2 will be that culture 1 will remain the same, while culture 2 will become F+, leucine-, histidine-. This is because in conjugation, the F factor (F plasmid) is transferred from the donor (F+) to the recipient (F-). Culture 1 is F+ and has the ability to produce the enzymes leucine and histidine, while culture 2 is F- and lacks these abilities. Therefore, after conjugation, culture 2 will acquire the F factor and become F+, but it will still lack the ability to produce leucine and histidine. Culture 1 will remain the same because it already has the F factor.Rate this question:
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- 29.
In Table 8.1, if culture 1 mutates to Hfr, what will be the result of conjugation between the two cultures?
- A.
They will both remain the same
- B.
1 will become F+, leu+, his+; 2 will become F+, leu+, his+
- C.
1 will remain the same; Recombination will occur in 2
- D.
1 will become F-, leu+, his+; 2 will become Hfr, leu+, his+
- E.
Can't tell
Correct Answer
C. 1 will remain the same; Recombination will occur in 2 -
- 30.
An enzyme produced in response to the presence of a substrate is called
- A.
An inducible enzyme.
- B.
A repressible enzyme.
- C.
A restriction enzyme.
- D.
An operator.
- E.
A promoter.
Correct Answer
A. An inducible enzyme.Explanation
An inducible enzyme is produced in response to the presence of a substrate. This means that when the substrate is present, it triggers the production of the enzyme. This mechanism allows the organism to regulate the production of the enzyme based on the need for it. In contrast, a repressible enzyme is produced continuously unless it is inhibited by a repressor molecule. A restriction enzyme is a type of enzyme that cuts DNA at specific recognition sites. An operator is a region of DNA where a repressor protein can bind to regulate gene expression. A promoter is a region of DNA where RNA polymerase binds to initiate transcription.Rate this question:
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- 31.
In which of the following ways do viruses differ from bacteria?
- A.
Viruses are filterable.
- B.
Viruses are obligate intracellular parasites.
- C.
Viruses don't have any nucleic acid.
- D.
Viruses are not composed of cells.
- E.
Viruses don't reproduce.
Correct Answer
D. Viruses are not composed of cells.Explanation
Viruses are different from bacteria because they are not composed of cells. While bacteria are single-celled organisms, viruses are considered non-living entities because they lack the characteristics of living cells. Instead, viruses are composed of genetic material (either DNA or RNA) surrounded by a protein coat called a capsid. They rely on host cells to replicate and carry out their life cycle. This fundamental difference in cellular composition distinguishes viruses from bacteria.Rate this question:
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- 32.
Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals?
- A.
They are not composed of cells.
- B.
They are filterable.
- C.
They cannot reproduce themselves outside a host.
- D.
They cause diseases similar to those caused by chemicals.
- E.
They are chemically simple.
Correct Answer
C. They cannot reproduce themselves outside a host.Explanation
The statement "They cannot reproduce themselves outside a host" provides the most significant support for the idea that viruses are nonliving chemicals. This is because reproduction is a characteristic of living organisms, and if viruses cannot reproduce on their own without a host, it suggests that they lack the necessary biological processes to be considered living.Rate this question:
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- 33.
Which of the following statements about spikes is false?
- A.
They are used for penetration.
- B.
They are used for absorption.
- C.
They may cause hemagglutination.
- D.
They are found only on enveloped viruses.
- E.
They are found only on nonenveloped viruses.
Correct Answer
A. They are used for penetration.Explanation
Spike proteins are used by viruses to attach to and enter host cells, but they are not used for penetration. Once attached, the spike proteins facilitate membrane fusion or endocytosis, allowing the virus to enter the host cell. Therefore, the statement "They are used for penetration" is false.Rate this question:
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- 34.
Which of the following is NOT used as a criterion to classify viruses?
- A.
Biochemical tests
- B.
Morphology
- C.
Nucleic acid
- D.
Size
- E.
Number of capsomeres
Correct Answer
A. Biochemical testsExplanation
Biochemical tests are not used as a criterion to classify viruses. Viruses are typically classified based on their morphology (shape), nucleic acid (DNA or RNA), size, and number of capsomeres. Biochemical tests, on the other hand, are used to identify and characterize microorganisms such as bacteria, fungi, and parasites. Viruses do not possess the necessary biochemical machinery to perform these tests, which is why they are not used as a criterion for their classification.Rate this question:
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- 35.
Which of the following is NOT a method of culturing viruses?
- A.
In laboratory animals
- B.
In culture media
- C.
In embryonated eggs
- D.
In cell culture
- E.
None of the above
Correct Answer
B. In culture mediaExplanation
Culture media refers to the nutrient-rich substances used to support the growth and reproduction of microorganisms. In the context of viruses, they cannot be cultured directly in culture media alone. Viruses require a host cell to replicate, so they can be cultured in laboratory animals, embryonated eggs, or in cell cultures derived from animal or human cells. Therefore, "In culture media" is the correct answer as it is not a method of culturing viruses on its own.Rate this question:
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- 36.
Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?
- A.
Adsorption
- B.
Penetration
- C.
Uncoating
- D.
Biosynthesis
- E.
Release
Correct Answer
D. BiosynthesisExplanation
Bacteriophages and animal viruses do not significantly differ in the biosynthesis step. Biosynthesis refers to the replication and production of viral components within the host cell. Both bacteriophages and animal viruses undergo a similar process of utilizing the host cell's machinery to replicate their genetic material and produce viral proteins. This step is crucial for the assembly of new virus particles. Therefore, the biosynthesis step is not a significant point of difference between bacteriophages and animal viruses.Rate this question:
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- 37.
The definition of lysogeny is
- A.
Phage DNA is incorporated into host cell DNA.
- B.
Lysis of the host cell due to a phage.
- C.
The period during replication when virions are not present.
- D.
When the burst time takes an unusually long time.
- E.
Attachment of a phage to a cell.
Correct Answer
A. pHage DNA is incorporated into host cell DNA.Explanation
Lysogeny is a process in which the DNA of a bacteriophage (phage) is integrated into the DNA of its host cell. This integration allows the phage DNA to be replicated along with the host cell's DNA during cell division. The integrated phage DNA is called a prophage and remains dormant within the host cell until certain conditions trigger its activation. This process is different from the lytic cycle, where the phage causes the host cell to burst and release new phage particles. Therefore, the correct answer is "Phage DNA is incorporated into host cell DNA."Rate this question:
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- 38.
A viroid is
- A.
A complete, infectious virus particle.
- B.
A nonenveloped, infectious piece of RNA.
- C.
A capsid without a nucleic acid.
- D.
A provirus.
- E.
An infectious protein.
Correct Answer
B. A nonenveloped, infectious piece of RNA.Explanation
A viroid is a nonenveloped, infectious piece of RNA. Unlike a complete virus particle, a viroid lacks a protein capsid and does not encode any proteins. Viroids are smaller than viruses and are composed solely of a short, single-stranded RNA molecule. They are able to infect plants and cause various diseases by interfering with the normal functioning of the host cell. Viroids are unique in their ability to replicate autonomously without the need for any viral proteins.Rate this question:
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- 39.
In Figure 13.1, which structure is a complex virus?
- A.
A
- B.
B
- C.
C
- D.
D
- E.
All of the above
Correct Answer
B. BExplanation
In Figure 13.1, structure b is a complex virus. This can be inferred because the question asks for a complex virus, and structure b is the only option that fits this description. The other structures (a, c, and d) may represent different types of viruses or other biological structures, but they are not specifically identified as complex viruses in the question. Therefore, the correct answer is b.Rate this question:
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- 40.
In Figure 13.1, the structures illustrated are composed of
- A.
DNA
- B.
RNA
- C.
DNA or RNA
- D.
Capsomeres
- E.
Capsids
Correct Answer
D. CapsomeresExplanation
The structures illustrated in Figure 13.1 are composed of capsomeres. Capsomeres are protein subunits that make up the capsid, which is the outer protein coat of a virus. The capsid protects the genetic material of the virus, which can be either DNA or RNA. Therefore, the correct answer is capsomeres.Rate this question:
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