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Immunity
- The body can fight against pathogens
- This natural ability is called immunity
- It is the body's first line of defence
- Innate immunity is present from birth
- Acquired immunity develops over time
- some children catch the infection
- others do not fall sick
- strong immunity protects them
- body fights germs once
- builds protection against them
- also gained from vaccines
- Innate immunity is present from birth; acquired immunity comes later.
- Immunity is the body's first line of defence against germs.
- A strong immune system explains why not everyone catches an infection.
Vaccines
- A vaccine is a special medicine
- It provides immunity against a disease
- Given to healthy persons for protection
- Made from bacteria or viruses
- Contains dead or weakened microbes
- weakened microbes enter the body
- body makes antibodies in blood
- antibodies kill the live microbes
- given orally to a child
- protects against polio disease
- builds long-lasting immunity
- Some antibodies stay in the blood for a long time and fight the microbe later.
- Diseases prevented by vaccines: polio, chickenpox, cholera, typhoid, hepatitis, TB, tetanus, measles, rabies, diphtheria, pertussis.
- Vaccine–disease pairs: DPT-Hib → diphtheria, tetanus, pertussis; BCG → tuberculosis; Covaxin/Covishield → COVID-19.
Name the following: It provides immunity against a particular disease.
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Explanation
- A vaccine is given to healthy people to protect them against a disease.
What is a vaccine? How does a vaccine work?
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Explanation
- A vaccine contains dead or weakened but harmless microbes of a disease.
- When given orally or by injection, the body produces antibodies in the blood.
- These antibodies kill the live disease-causing microbes.
- Some antibodies remain for a long time and fight the same microbe if it enters later.
- So the person stays protected from that disease.
There is a flu outbreak in your school. Several classmates are absent, while some are still coming to school coughing and sneezing. (a) What immediate actions should the school take to prevent further spread? (b) If your classmate, who shares the bench with you, starts showing symptoms of the flu, how can you respond in a considerate way without being rude or hurtful? (c) How can you protect yourself and others from getting infected in this situation? (NCERT Book Question)
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Explanation
- (a) The school can ask sick students to stay home and rest, clean and ventilate classrooms, and spread awareness about covering coughs and washing hands.
- (b) Gently suggest the classmate go home or see a doctor, offer to share notes, and avoid making them feel blamed or embarrassed.
- (c) Cover your mouth and nose, wash hands often, keep a safe distance, and avoid sharing food or items.
When our body encounters a pathogen for the first time, the immune response is generally low but on exposure to the same pathogen again, the immune response by the body is much more compared to the first exposure. Why is it so? (NCERT Book Question)
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Explanation
- On first contact, the body needs time to make antibodies, so the response is slow and low.
- Some antibodies and memory remain in the blood for a long time.
- On the next exposure, these act quickly, giving a much stronger response.
The vaccine for smallpox was discovered by:
- (a) Alexander Fleming
- (b) Edward Jenner
- (c) Louis Pasteur
- (d) Robert Koch
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Explanation
- Jenner discovered the smallpox vaccine in 1796 using cowpox.
One way to prevent the following disease is by vaccination. Which disease can it be?
- (a) giardia
- (b) typhoid
- (c) ascariasis
- (d) malaria
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Explanation
- Typhoid can be prevented by vaccination along with good hygiene.
The natural ability of the body to fight infection against germs is called:
- (a) disorder
- (b) immunity
- (c) vaccine
- (d) disease
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Explanation
- Immunity is the body's natural defence against pathogens.
The vaccine given to treat tuberculosis is:
- (a) DPT
- (b) Covaxin
- (c) Polio
- (d) BCG
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Explanation
- The BCG vaccine protects against tuberculosis.
