🌸Chapter 7
Human Health and Diseases
(4 Marks)
Q1. What is immunity? Explain the
differences between innate and acquired immunity.
Answer:
Immunity is the ability of the body to resist or fight against
disease-causing organisms.
- Innate Immunity:
- Present from birth.
- Non-specific (acts against all
pathogens).
- Includes physical barriers
(skin), physiological barriers (HCl, saliva), cellular barriers
(phagocytes), and cytokine barriers (interferons).
- Acquired Immunity:
- Develops after exposure to
antigens.
- Specific and has memory.
- Two types: active (natural
infection/vaccination) and passive (antibodies from mother or injection).
Q2. Explain the role of the immune
system in allergic reactions.
Answer:
- Allergy is a hypersensitive
response of the immune system to certain harmless substances (allergens
like pollen, dust).
- Allergen stimulates B-cells
to produce IgE antibodies.
- These antibodies bind to mast
cells, releasing chemicals like histamine and serotonin.
- These cause symptoms like
sneezing, watery eyes, and inflammation.
- Antihistamine drugs are used to control allergic
reactions.
Q3. Explain the structure of an
antibody molecule.
Answer:
- Antibodies are Y-shaped
glycoproteins called immunoglobulins (Ig).
- Composed of two heavy chains
and two light chains joined by disulfide bonds.
- Each antibody has two
antigen-binding sites (Fab region).
- The variable region
binds to the antigen, while the constant region determines the
antibody class (IgG, IgA, IgM, IgE, IgD).
Q4. Distinguish between active and
passive immunity with suitable examples.
Answer:
|
Feature |
Active Immunity |
Passive Immunity |
|
Definition |
Body produces antibodies in response to antigen |
Ready-made antibodies are transferred |
|
Memory |
Long-lasting, memory developed |
Short-lived, no memory |
|
Example |
Vaccination, natural infection |
Colostrum (mother’s milk), anti-tetanus serum |
Q5. Describe how vaccination helps
in developing immunity.
Answer:
- Vaccination introduces weakened or
killed pathogens into the body.
- This triggers the immune system
to produce antibodies and memory cells.
- Upon future exposure to the
same pathogen, memory cells respond quickly and prevent disease.
- Examples:
- BCG (for tuberculosis)
- DPT (for diphtheria,
pertussis, tetanus)
- OPV (oral polio vaccine)
Q6. What is the difference between
an antigen and an antibody?
Answer:
|
Term |
Definition |
Example |
|
Antigen |
Any foreign substance that induces an immune response |
Bacterial cell wall protein |
|
Antibody |
A Y-shaped protein produced by B-lymphocytes that
neutralizes antigens |
Immunoglobulin G (IgG) |
Q7. What are interferons? Mention
their role.
Answer:
- Interferons are proteins produced
by virus-infected cells.
- They act as signaling molecules
that inhibit viral replication in neighboring cells.
- They boost the activity of natural
killer (NK) cells and macrophages.
- Used in therapy against viral
infections and certain cancers.
Q8. Explain the life cycle of Plasmodium
in humans.
Answer:
- Plasmodium enters human blood through the
bite of a female Anopheles mosquito.
- Sporozoites infect liver cells
→ multiply to form merozoites.
- Merozoites enter RBCs →
multiply → rupture RBCs → release toxins causing fever.
- Some develop into gametocytes →
taken up by mosquito → complete sexual cycle in mosquito gut.
Q9. What are the main symptoms and
preventive measures of malaria?
Answer:
Symptoms:
- High fever with chills,
headache, sweating, nausea.
Prevention: - Avoid mosquito bites (use nets,
repellents).
- Drain stagnant water (prevent
breeding).
- Use of anti-malarial drugs like
chloroquine.
- Government programs like National
Anti-Malaria Programme (NAMP).
Q10. Describe the pathogen, mode of
transmission, and prevention of amoebiasis.
Answer:
- Pathogen: Entamoeba histolytica
- Mode of transmission: Through contaminated food and
water (fecal-oral route).
- Symptoms: Abdominal pain, cramps,
diarrhea with blood and mucus.
- Prevention: Maintain sanitation, wash
fruits/vegetables, drink clean water.
Q11. What is ringworm? Mention its
causative agent and prevention.
Answer:
- Ringworm is a fungal infection
of the skin.
- Causative agent: Microsporum, Trichophyton,
Epidermophyton.
- Symptoms: Circular patches on skin,
itching, redness.
- Prevention: Maintain personal hygiene,
avoid sharing towels/clothes, keep skin dry.
Q12. Describe the modes of
transmission of HIV/AIDS.
Answer:
HIV spreads through:
1.
Unprotected
sexual contact with infected person.
2.
Transfusion
of infected blood.
3.
Sharing
contaminated needles.
4.
From
infected mother to child during pregnancy, birth, or breastfeeding.
Not spread by: Touch, handshake, mosquito bites, sharing food.
Q13. Explain the role of
T-lymphocytes in immunity.
Answer:
- Helper T-cells (Th): Activate B-cells and
macrophages.
- Cytotoxic T-cells (Tc): Destroy virus-infected cells
and tumor cells.
- Suppressor T-cells (Ts): Regulate and suppress immune
responses.
- Memory T-cells: Retain memory of the antigen
for faster future response.
Q14. Explain the effects of HIV on
the immune system.
Answer:
- HIV infects CD4+ helper
T-cells, reducing their count.
- This weakens the immune system.
- Body becomes vulnerable to
infections (e.g., TB, pneumonia) and certain cancers.
- Leads to AIDS (Acquired
Immuno Deficiency Syndrome).
Q15. Describe the process of
inflammation during infection.
Answer:
- Inflammation is the body’s
response to infection or injury.
- Steps:
1.
Damaged
cells release histamines.
2.
Blood
flow increases, causing redness and warmth.
3.
White
blood cells migrate to the site to engulf pathogens.
4.
Swelling
and pain occur due to accumulation of fluids.
Q16. Explain the role of vaccines in
controlling infectious diseases.
Answer:
- Vaccines contain inactivated
or weakened pathogens.
- They stimulate immune system to
form antibodies and memory cells.
- On later exposure, body
responds rapidly, preventing disease.
- Helps control diseases like
smallpox, polio, and measles globally.
Q17. What are lifestyle diseases?
Give examples and preventive measures.
Answer:
- Diseases resulting from
unhealthy lifestyle habits.
- Examples: Obesity, hypertension,
diabetes, heart disease.
- Prevention: Balanced diet, regular
exercise, stress management, avoiding smoking/alcohol.
Q18. What are carcinogens? Give
examples.
Answer:
- Carcinogens are substances that cause
cancer by inducing mutations.
- Examples:
- Physical: X-rays, UV rays
- Chemical: Tobacco smoke,
aflatoxin
- Biological: Certain viruses
(e.g., HPV, Hepatitis B)
Q19. Explain the difference between
benign and malignant tumors.
Answer:
|
Feature |
Benign |
Malignant |
|
Growth |
Slow |
Rapid |
|
Spread |
Localized |
Spreads (metastasis) |
|
Recurrence |
Rare |
Common |
|
Example |
Warts |
Cancer |
Q20. Describe the role of
carcinogens in cancer formation.
Answer:
- Carcinogens cause mutations in proto-oncogenes
and tumor suppressor genes.
- This leads to uncontrolled cell
division.
- Formation of tumor cells occurs
→ metastasis → cancer.
Q21. What are autoimmune diseases? Give
examples.
Answer:
- When the immune system attacks
body’s own cells.
- Examples:
- Rheumatoid arthritis – joints inflamed.
- Type-1 Diabetes – immune cells destroy
pancreatic β-cells.
Q22. Write short notes on Adolescence
and Drug Abuse.
Answer:
- Adolescents face stress,
curiosity, peer pressure.
- Drugs like opioids,
cannabinoids, cocaine affect CNS.
- Causes dependence, mental
disorders, liver and heart damage.
- Prevention: Counseling, awareness, healthy
lifestyle, family support.
Q23. Differentiate between opioids
and cannabinoids.
Answer:
|
Feature |
Opioids |
Cannabinoids |
|
Source |
Papaver somniferum (poppy) |
Cannabis sativa |
|
Examples |
Morphine, Heroin |
Marijuana, Hashish |
|
Effect |
Depress CNS, reduce pain |
Affect brain activity and mood |
Q24. What are withdrawal symptoms in
drug abuse?
Answer:
- When a drug-dependent person
stops taking it, they experience:
- Anxiety, restlessness, nausea,
tremors, sweating, depression.
- Indicate physical and
psychological dependence.
- Medical help is needed for
recovery.
Q25. Suggest measures to prevent and
control drug/alcohol abuse among youth.
Answer:
- Education & Awareness: Include in school curriculum.
- Counseling &
Rehabilitation:
For affected individuals.
- Peer & Family Support: Positive environment.
- Strict Laws: Ban on drug trafficking and
alcohol for minors.
