Questions and Answers
Viruses are considered nonliving because:
Why is the study of viruses a part of biology?
Because they are active inside living cells.
What do biologists now know about viruses?
They contain RNA or DNA in a protein or lipid protein coat.
What is the capsid of a virus?
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Viruses are classified according to:
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What do all viruses not have?
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Which statement is true about the Tobacco mosaic virus?
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Why did scientists first begin to study viruses?
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What are viruses that use reverse transcriptase to cause their host cells to transcribe DNA from an RNA template called?
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Which of the following contains only RNA?
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Unlike viruses, prions are composed only of protein.
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What does a typical virus consist of?
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Viruses reproduce only in living cells.
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Why do animal viruses often infect only specific host cells?
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In which cell cycle do viral DNA become integrated into the host cell's DNA?
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Why are antibiotics ineffective against viral infections?
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Which of the following are viral diseases of humans?
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Which of the following is not linked to cancer?
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Which human activity is most closely associated with the emergence of viruses not previously seen in humans?
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Most scientists think that early viruses originated from?
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How does HIV cause AIDS?
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Which of the following is not a vector of viral diseases?
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Which approach has been the most successful at fighting viral diseases?
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Most scientists believe that viruses first appeared on the earth ________ living cells appeared.
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The protein coat of a virus is called a ______.
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Viruses can vary in size and?
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What is a virus that transcribes DNA from an RNA template called?
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An enzyme called _____________ _______________ manufactures DNA that is complementary to a virus's RNA.
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What are bacteriophages?
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All viruses reproduce by taking over the reproductive machinery of a?
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Viruses that infect a host cell and have their nucleic acid replicated but do not harm the host cell are in a __________ cycle.
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Some viruses are thought to induce ____________, a disease characterized by uncontrolled cell division.
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In the _______ cycle, viruses destroy the host cell.
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Chickenpox and __________ are caused by the same virus.
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Explain why viruses are not considered to be living organisms.
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Why are viruses nonetheless included in the study of biology?
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Study Notes
Virus Characteristics
- Viruses are nonliving due to inability to reproduce independently, lack of cellular structure, and inability to carry out metabolism outside host cells.
- They are composed of either RNA or DNA contained within a protective protein or lipid coat called a capsid.
- All viruses lack cytoplasm, mitochondria, and ribosomes.
Virus Classification
- Classification is based on the type of nucleic acid (RNA or DNA), genomic shape, and the presence of a membrane envelope.
- Viroids consist solely of RNA and lack a protein coat.
Specific Viruses and Their Effects
- The Tobacco Mosaic Virus can be crystallized and is smaller than bacteria, causing disease in tobacco plants.
- Retroviruses utilize reverse transcriptase to transcribe DNA from RNA, which is critical in their replication process.
- Bacteriophages are viruses specifically infecting bacteria with characteristic polyhedral heads and helical tails.
Infection and Disease Mechanisms
- Viruses reproduce by hijacking the reproductive machinery of host cells, occurring within the lytic cycle (cell destruction) or lysogenic cycle (host cell integration without immediate harm).
- Animal viruses infect specific host cells due to the presence of matching receptors on cell surfaces.
Health and Prevention
- Viral diseases in humans include Hepatitis, SARS, and shingles, while Ebola is not linked to cancer.
- Vaccination and vector control are the most effective methods for combating viral diseases.
- Antibiotics are ineffective against viral infections as they target processes that viruses do not perform.
Historical and Ecological Context
- Most scientists theorize that early viruses evolved from existing cellular components.
- Human activities, particularly deforestation for housing, are significant contributors to the emergence of new viruses.
Viral Implications in Biology
- Despite being nonliving, viruses are included in biological studies because they interact and operate within living cells, significantly impacting cellular mechanisms and health.
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Description
Explore the fascinating world of viruses with this quiz covering their characteristics, classification, and specific types. From the structure of viruses to their methods of infection, test your knowledge on how these nonliving entities affect living organisms. Dive into concepts such as RNA, DNA, and bacteriophages in your answers.
