Virus Biology Quiz

Chapter 7 Lesson 3: What are Viruses?

• Viruses are strands of DNA or RNA surrounded by a protein layer.
• They can infect and replicate inside host cells.
• Viruses lack cell walls, nuclei, and other organelles found in cells.
• Viruses come in various shapes, including crystal, cylinder, sphere, and bacteriophage shapes.
• A bacteriophage is a virus that infects and replicates within bacteria.
• Viruses are not living organisms as they lack the characteristics of living organisms.
• Viruses replicate by using a host cell as a factory, creating thousands of new viruses.
• Viruses can only attach to host cells using specific molecules on the host cell's membrane.
• Viral replication can be active or latent (dormant).
• Latent viruses go inactive, while active viruses immediately begin replicating.
• Viruses frequently mutate.
• Mutations happen quickly, making it difficult to treat viral diseases.
• Viruses mutate to develop new ways of attaching to host cells.
• Viral diseases affect humans.
• Viral diseases include mumps, measles, chicken pox, influenza (flu), hepatitis B & C, COVID-19, and AIDS.
• Viruses also infect plants.
• Viral infections destroy cells, causing disease symptoms
• Symptoms often appear soon after infection.
• Flu virus infects the respiratory system and symptoms (like a runny nose and scratchy throat) appear within 2-3 days of infection.
• Entry to the body typically occurs through the nose or mouth.
• Viruses travel to the lungs, where they infect cells and replicate.

Replication in Viruses

• Replication is the process by which viruses reproduce and create copies.
• Viruses attach to a host cell.
• Viral genetic material is inserted into the host cell.
• Once the virus has its genetic material in the host cell, it can become latent or active.
• When active, the viral genetic material takes control of the host cell, making copies of the virus.
• New viruses are released as the host cell bursts.

Mutations

• Mutations are changes in genetic material.
• Viruses mutate, or change, their DNA or RNA frequently.
• Mutations enable viruses to adapt to changes in their host cells.
• Mutations are a major reason why viruses are so difficult to treat.

Viral Diseases

• Viruses cause many human diseases.
• Viral diseases include mumps, measles, chicken pox, influenza, Hepatitis B & C, COVID-19, and AIDS.
• Viruses also infect plants.
• Viral infections destroy cells, which leads to the symptoms of the disease.

Treating and Preventing Viral Diseases

• Viral diseases are difficult to treat because viruses change so quickly.
• Antiviral medicines can stop viral replication but viruses can rapidly change to become resistant to these medicines.
• Limiting contact with infected people or animals can prevent viral infections.
• Frequent handwashing is important for prevention.
• Vaccines create antibodies designed to battle specific viruses, giving immunity against future infections.
• Natural immunity is immunity a person is born with. It happens when a mother passes antibodies to her unborn baby, meaning the baby starts with the immune defence mechanism

Immunity

• Immunity comes from the Latin word immunis, meaning exempt or free.
• Immunity is a body's defence mechanism used to fight against viruses and bacteria.
• When people get infected and survive, their bodies develop protection against that disease. This is called acquired immunity.
• A virus infects a person, and the body produces antibodies.
• Antibodies are proteins that attach to pathogens, preventing them from infecting a host cell.
• Antibodies thus help the body fight diseases.

Research with Viruses

• Scientists must always look at new ways to treat and prevent viral infections, since viruses change so quickly.
• Viruses are used to treat genetic disorders and cancer, introducing normal genetic information into specific cells.

Review

• A virus is a strand of DNA or RNA surrounded by a protein layer.
• Viruses cause human diseases, such as chicken pox and the flu.
• The body produces antibodies as a defense mechanism against viruses.

Review Questions

• What is the body's defense mechanism to fight viruses? (Antibodies)
• Which is not caused by a virus? (Tuberculosis)
• Which statement correctly describes viruses? (Viruses do not have organelles)
• What is a pathogen? (Organism that causes disease)
• What is a vaccine? (Mixture containing material from deactivated pathogens)

Test your knowledge about viruses with this quiz. Explore key concepts such as the body's defenses against viruses, the nature of viral diseases, and the function of vaccines. Challenge yourself to answer questions related to the characteristics and genetic material of viruses.