BIO 122 - Exam 3: Immune System, Vaccines, Viruses and Herd Immunity, Covid and Zoonotic Diseases

A student experiences chronic stress and becomes sick more frequently. Why might this happen?

Stress can reduce immune response, making it harder to fight infections

Why can an immune response that is too strong be harmful?

It can cause excessive inflammation and other health problems

A person has an immune response that is too weak. What problem might they experience?

It may make it harder for the body to fight infections

A patient is exposed to an allergen, and immune cells trigger inflammation. Which cells are involved?

Mast cells

Where are mast cells made?

Red bone marrow

Why can excessive mast cell activation contribute to asthma?

Mast cells can release leukotrienes that narrow the airways

Which two structures are main components of the lymphatic system?

Lymphatic vessels and lymph nodes

A disease interferes with the movement of lymph fluid. Which system is most directly affected?

Lymphatic system

What happens to the lymphatic system when the body fights an infection?

It becomes more active

What does the lymphatic system do?

It helps fight infectious diseases

What is the main purpose of vaccination (immunization)?

To stimulate the immune system to produce memory cells by exposing it to an antigen

A scientist develops a vaccine using fragments of proteins from a virus. Why can this vaccine help protect someone without giving them the full virus?

The protein fragments stimulate an immune response that can produce memory cells

A community has high vaccination rates, which reduces the spread of a contagious pathogen. How does this help immunocompromised people?

It reduces the chance that they will encounter the pathogen because its spread is hindered

How does a DNA vaccine work?

It injects DNA containing instructions for making a viral protein, which triggers an immune response

A disease is constantly present at a relatively stable, normal level in a particular region. What is this disease's status called?

Endemic

A person receives an additional vaccine dose months after their initial vaccination. What is this additional dose called?

Booster shot

A person encounters a pathogen for the first time. Their T-cells and B-cells become activated, antibody levels increase, and memory cells develop over approximately 7–10 days. Which immune response is occurring?

Primary response

A person is exposed to the same pathogen for a second time. Their immune system responds faster and more strongly than before. Why?

Memory cells help the immune system recognize and respond to the pathogen

A virus accumulates small mutations over time, gradually changing the antigens on its surface. What is this process called?

Antigenic drift

Two different strains of a virus exchange genetic material, resulting in a major change in the antigens on the virus's surface. What is this called?

Antigenic shift

A student claims that antigenic drift and antigenic shift are the same process because both change viral antigens. Which statement best explains the difference?

Drift involves gradual mutations, while shift involves the exchange of genetic material between different viral strains

A disease spreads from an infected animal to a human. How is this disease classified?

A zoonotic disease

Scientists eliminate a disease from the human population through extensive vaccination, but the pathogen remains in a wild animal population. Why could the disease reappear?

The pathogen has a reservoir in which it can persist

Why can zoonotic diseases be difficult to eliminate completely?

Pathogens may persist in animal reservoirs or other infected species

A vaccine does not completely eliminate a zoonotic disease, but vaccinated populations experience less transmission. What does this demonstrate?

Vaccines can reduce the spread of disease without necessarily eliminating the pathogen from every reservoir

A virus infects one person and then spreads to several other people. What is this human-to-human spread called?

Contagion

A virus infects an animal species but cannot initially infect humans. Eventually, it overcomes barriers that allow it to infect humans. What is this process called?

Spillover

A disease experiences a sudden increase in cases across several countries on more than one continent. Which term best describes this situation?

Pandemic

A disease causes a sudden increase in cases across a large population within one country, without widespread transmission across multiple continents. Which term best fits?

Epidemic

A virus spills over from an animal into a human. Months later, it spreads rapidly between people and across multiple continents. Which sequence best describes these events?

Spillover → Contagion → Pandemic

A pathogen remains in an animal reservoir and can evolve in that host or in other infected species. Why does this make elimination more challenging?

The pathogen can persist and evolve outside the human population