Diseases And Immunity

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课程笔记

Pathogens & Barriers

A pathogen is a disease-causing organism that causes transmissible diseases.
Pathogens spread via direct contact (e.g., HIV through body fluids) or indirect contact (e.g., airborne droplets).
Viruses (e.g., cold, flu) are not living; they consist of genetic material (RNA/DNA) inside a protein coat and hijack host cells to replicate.
Mechanical barriers: skin (physical barrier, heals with scabs), nose hairs (trap pathogens).
Chemical barriers: mucus (traps pathogens, removed by coughing/sneezing), stomach acid (HCl kills swallowed pathogens).
White blood cells defend by phagocytosis (engulfing pathogens) and producing antibodies (cause agglutination and signal destruction).

Methods of Transmission

Controlling the Spread of Disease

Clean water supply prevents waterborne diseases like cholera.
Hygienic food preparation (washing hands, proper cooking) prevents contamination by bacteria/fungi.
Personal hygiene (soap, tissues for sneezes/coughs) reduces transmission of colds and flu.
Waste disposal (e.g., food waste) reduces vectors like flies.
Sewage treatment removes pathogens from waste before release into environment.

Preventing the Spread of Disease

Active Immunity (Extended)

Active immunity is the production of antibodies and memory cells after exposure to a pathogen.
It can be acquired naturally (infection) or artificially (vaccination).
Active immunity is slow-acting but provides long-lasting protection.

Antigens & Antibodies (Extended)

Antigens are molecules (e.g., proteins) on cell surfaces that are recognised as foreign by lymphocytes.
Antibodies are proteins produced by lymphocytes that are complementary in shape to specific antigens.
Antibodies cause agglutination (clumping) of pathogens, making them easier for phagocytes to engulf and destroy.
After infection, memory cells retain antibody instructions for a faster, stronger response on re-exposure.
Some pathogens mutate quickly, changing antigens so memory cells may not recognise them.

Lymphocytes produce antibodies specific to an antigen

Vaccination (Extended)

Vaccines contain dead or weakened pathogens with specific antigens, unable to cause disease.
Vaccination triggers an immune response: lymphocytes produce antibodies and memory cells.
Memory cells provide long-lasting immunity without the risk of severe illness.
Herd immunity occurs when a large percentage of the population is vaccinated, protecting the unvaccinated by reducing pathogen spread.
Vaccination programmes aim to eradicate diseases (e.g., smallpox eradicated in 1980).

How a vaccine produces long-term immunity

Preventing the Spread of Disease

Vaccination helps control spread; not all diseases have vaccines.
Immune individuals cannot catch or spread the disease.
Herd immunity prevents epidemics/pandemics by limiting pathogen breeding opportunities.
If vaccination rates drop, outbreaks can occur, increasing infections and deaths.

Herd immunity

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练习题

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1.Which of the following is a pathogen?
Easy
- AVirus
- BRed blood cell
- CLymphocyte
- DAntibody
2.Viruses are considered living organisms because they can reproduce on their own.
Easy
True or false?
3.Name one mechanical barrier that helps prevent pathogens from entering the body.
Easy
4.Which type of white blood cell engulfs and digests pathogens?
Easy
- ALymphocyte
- BPhagocyte
- CMemory cell
- DErythrocyte
5.Complete the sentence: Antibodies are produced by ___ in response to foreign ___.
Easy
Antibodies are produced by ____ in response to foreign ____.
6.What is the role of memory cells in immunity?
Medium
7.Vaccination introduces a live, active pathogen into the body to stimulate an immune response.
Easy
True or false?
8.Define herd immunity.
Medium

更多题目

9.Why does a person not get ill from the same pathogen a second time?
Medium
- AMemory cells produce antibodies quickly
- BThe pathogen mutates
- CPhagocytes destroy the pathogen immediately
- DAntibodies remain in the blood forever
10.State one method of indirect transmission of a pathogen.
Easy
11.Match each type of white blood cell to its function.
Medium
- Phagocyte
- Lymphocyte
- Memory cell
- Engulfs pathogens
- Produces antibodies
- Retains antibody instructions
12.Arrange the following events in the correct order for an immune response to a first infection: (a) Memory cells are formed, (b) Pathogen enters body, (c) Antibodies are produced, (d) Pathogen is destroyed.
Medium
- Pathogen enters body
- Antibodies are produced
- Pathogen is destroyed
- Memory cells are formed
13.What is a pathogen?
Easy
- AA disease-causing organism
- BA type of white blood cell
- CA chemical that kills bacteria
- DA protein that neutralises toxins
14.Which of the following is a mechanical barrier that helps prevent pathogens from entering the body?
Easy
- AMucus
- BStomach acid
- CSkin
- DAntibodies
15.Match each type of barrier to the correct example.
Easy
- Mechanical barrier
- Chemical barrier
- Hairs in the nose
- Stomach acid
- Mucus
16.Arrange the following events in the correct order for the immune response to a first infection by a pathogen.
Medium
- Memory cells are formed
- Pathogen enters body
- Lymphocytes produce antibodies
- Phagocytes engulf pathogens
- Antibodies cause agglutination
17.Which of the following are ways in which the body defends itself against pathogens? (Select all that apply)
Medium
- ASkin
- BMucus
- CStomach acid
- DRed blood cells
- EAntibodies
18.A pathogen is a disease-causing organism.
Easy
True or false?
19.Which of the following is a chemical barrier that helps prevent pathogens from entering the body?
Easy
- AHairs in the nose
- BSkin
- CMucus
- DCilia
20.Which of the following are measures that help control the spread of disease? (Select all that apply)
Medium
- AClean water supply
- BHygienic food preparation
- CPersonal hygiene
- DUse of antibiotics
- ESewage treatment
21.Arrange the following steps in the correct order for how a vaccine provides immunity.
Medium
- Memory cells are formed
- Weakened pathogen introduced into body
- Lymphocytes produce antibodies
- Rapid response to future infection
22.A student investigates the effect of different concentrations of disinfectant on the growth of bacteria. Which of the following is the independent variable in this experiment?
Medium
- AConcentration of disinfectant
- BTemperature of incubation
- CNumber of bacteria colonies
- DType of bacteria
23.A researcher measures the number of cases of a disease in two towns over one year. Town A has 90% vaccination coverage and reports 10 cases per 10,000 people. Town B has 60% vaccination coverage and reports 200 cases per 10,000 people. Which conclusion is best supported by this data?
Hard
- AHigher vaccination coverage reduces the number of disease cases.
- BThe disease is more infectious in Town B.
- CVaccination has no effect on disease spread.
- DTown A has better healthcare than Town B.
24.Which of the following are methods of indirect transmission of pathogens? (Select all that apply)
Medium
- ACoughing and sneezing
- BSexual contact
- CContaminated food
- DBlood transfusion
- EInsect vectors
25.A vaccine works by introducing weakened or dead pathogens that stimulate the production of memory cells without causing disease.
Easy
True or false?
26.Arrange the following events in the correct order for how a vaccine provides immunity.
Medium
- Memory cells are produced
- Weakened pathogen is introduced
- Antibodies are produced
- Rapid response on re-exposure
27.Which structure inside a phagocyte contains its genetic material and controls its activities?
Easy
- ANucleus
- BCytoplasm
- CCell membrane
- DPseudopodium
28.The graph shows antibody concentration in the blood after two exposures to the same pathogen. Which statement explains the difference between the first and second response?
Medium
- AMemory cells produce antibodies faster and in greater quantity on second exposure.
- BThe second exposure is to a weaker strain of the pathogen.
- CAntibodies from the first infection remain active for years.
- DThe immune system is slower to respond the second time.
29.A student investigates the effect of different concentrations of disinfectant on the growth of bacteria. Which of the following is the dependent variable in this experiment?
Easy
- AConcentration of disinfectant
- BTemperature of the incubator
- CAmount of bacterial growth
- DType of disinfectant
30.A researcher measures the number of cases of a disease in two towns over one year. Town A has 90% vaccination coverage and reports 10 cases per 10,000 people. Town B has 50% vaccination coverage and reports 200 cases per 10,000 people. Which conclusion is best supported by the data?
Medium
- AVaccination has no effect on disease incidence
- BHigher vaccination coverage reduces disease incidence
- CTown B has a more effective healthcare system
- DThe disease is more infectious in Town A
31.A student wants to test the effect of different hand-washing soaps on the number of bacteria on hands. Which of the following should be kept constant?
Easy
- AType of soap
- BDuration of hand washing
- CNumber of bacteria before washing
- DTemperature of water
32.A vaccine introduces a live, active pathogen into the body to stimulate an immune response.
Easy
True or false?
33.The graph shows antibody concentration in the blood after two exposures to the same pathogen. Which statement explains the difference between the first and second responses?
Medium
- AThe first response is faster because memory cells are already present.
- BThe second response is faster and greater because memory cells produce antibodies quickly.
- CBoth responses are identical because the same pathogen is involved.
- DThe second response is slower because the pathogen has mutated.
34.A student investigates the effectiveness of three different hand soaps (A, B, C) in reducing bacterial numbers on hands. The student rubs a sample from each hand onto an agar plate, incubates, and counts the number of bacterial colonies. Which variable should be kept constant to ensure a fair test?
Easy
- AThe type of soap used
- BThe incubation temperature
- CThe number of bacterial colonies counted
- DThe brand of agar plate
35.Which of the following are examples of indirect transmission of pathogens? (Select all that apply)
Medium
- AShaking hands with an infected person
- BDrinking water contaminated with sewage
- CInhaling droplets from a sneeze
- DSexual contact with an infected person
- EEating undercooked food containing bacteria
36.Antibodies are produced by phagocytes in response to infection.
Easy
True or false?
37.Match each white blood cell to its function.
Easy
- Phagocyte
- Lymphocyte
- Engulfs and digests pathogens
- Produces antibodies
38.The graph shows antibody concentration in the blood after two exposures to the same pathogen. Which statement best explains why the second exposure produces a faster and larger antibody response?
Medium
- AThe pathogen is weaker the second time
- BMemory cells produce antibodies immediately
- CPhagocytes engulf the pathogen more quickly
- DThe body has more white blood cells overall
39.A vaccine contains weakened pathogens. Why are weakened pathogens used instead of live, active ones?
Medium
- AWeakened pathogens reproduce faster
- BWeakened pathogens cannot cause disease but still stimulate an immune response
- CWeakened pathogens produce more antibodies
- DWeakened pathogens are easier to store
40.A student wants to investigate the effect of different concentrations of a disinfectant on the growth of bacteria. Which of the following should be kept constant?
Easy
- ATemperature of incubation
- BConcentration of disinfectant
- CNumber of bacterial colonies
- DType of disinfectant
41.A researcher measures the number of cases of a disease in two towns over one year. Town A has 90% vaccination coverage and reports 10 cases per 10,000 people. Town B has 60% vaccination coverage and reports 150 cases per 10,000 people. Which statement best explains the difference?
Medium
- ATown A has herd immunity, so the pathogen cannot spread easily.
- BTown B has a more infectious strain of the pathogen.
- CTown A has better sanitation than Town B.
- DTown B has a larger population than Town A.
42.The graph shows antibody concentration in the blood after two exposures to the same pathogen. Which statement best explains why the second exposure produces a faster and larger response?
Medium
- AMemory cells quickly produce antibodies specific to the pathogen.
- BPhagocytes engulf the pathogen more rapidly after the first exposure.
- CThe pathogen is weaker during the second exposure.
- DThe body produces more stomach acid to kill the pathogen.
43.Antigens are proteins produced by lymphocytes that attach to pathogens.
Easy
True or false?
44.A student investigates the effect of a disinfectant on bacterial growth. She soaks paper discs in four different concentrations of disinfectant (0%, 0.5%, 1.0%, 2.0%) and places them on an agar plate inoculated with bacteria. After 24 hours, she measures the diameter of the clear zone (zone of inhibition) around each disc. Which variable is the independent variable?
Easy
- Aconcentration of disinfectant
- Bdiameter of clear zone
- Ctype of bacteria
- Dtime of incubation
45.Complete the sentence.
Easy
Antibodies are produced by ____ in response to foreign ____.
46.Complete the sentence about the immune response.
Medium
Lymphocytes produce ____ that are complementary in shape to the ____ on the surface of pathogens.
47.State one method of direct transmission of a pathogen.
Easy
48.In a population of 10,000 people, 8,500 are vaccinated against a disease. What is the percentage of the population that is vaccinated?
Easy
49.In a population of 50,000 people, 42,500 are vaccinated against a disease. Calculate the percentage of the population that is vaccinated.
Easy
50.State one chemical barrier that helps prevent pathogens from entering the body.
Easy
51.Complete the sentence about herd immunity.
Easy
Herd immunity occurs when a large percentage of the population is vaccinated, reducing the spread of the pathogen and protecting those who are not immune because the pathogen has few ____ to reproduce.
52.Explain why a person does not get ill from the same pathogen a second time.
Medium
53.Explain why a person who has recovered from chickenpox is unlikely to get it again, but may get a cold caused by a different virus.
Hard
54.Explain why a person who has recovered from measles is unlikely to get measles again, but may get a cold caused by a different virus.
Hard
55.In a population of 10,000 people, 8,500 are vaccinated against a disease. What is the percentage of the population that is vaccinated?
Easy
- A103 %
- B85 %
- C94 %
- D76 %
56.In a population of 50,000 people, 42,500 are vaccinated against a disease. Calculate the percentage of the population that is vaccinated.
Easy
- A76 %
- B103 %
- C94 %
- D85 %

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