🌸Chapter 7
Human Health and Diseases
(5 Marks)
Q1. Define health. Explain the
factors affecting human health and the significance of maintenance of health.
Answer:
- Health is a state of complete
physical, mental, and social well-being and not merely the absence of
disease (WHO).
Factors affecting health:
1.
Genetic
factors:
Hereditary diseases like diabetes, hemophilia.
2.
Environmental
factors:
Pollution, sanitation, living conditions.
3.
Psychological
factors: Stress,
anxiety, depression.
4.
Lifestyle
factors: Diet,
exercise, habits (smoking, alcohol).
Significance:
- Promotes productivity and
longevity.
- Strengthens immunity and mental
stability.
- Reduces risk of lifestyle and
communicable diseases.
Q2. Differentiate between infectious
and non-infectious diseases with examples. Describe modes of transmission of
infectious diseases.
Answer:
|
Infectious |
Non-Infectious |
|
Caused by pathogens (bacteria, virus, fungi, protozoa) |
Not caused by pathogens (genetic, lifestyle) |
|
Transmissible |
Non-transmissible |
|
Example: Malaria, Typhoid |
Example: Diabetes, Hypertension |
Modes of transmission:
1.
Air-borne: Common cold, tuberculosis.
2.
Water-borne: Cholera, amoebiasis.
3.
Vector-borne: Malaria, dengue.
4.
Contact: AIDS, syphilis.
5.
Through
food: Food
poisoning.
Q3. Explain the concept of immunity.
Discuss in detail the types of immunity in humans.
Answer:
Immunity: The ability of the body to resist infection.
Types:
1.
Innate
Immunity:
o Present from birth.
o Non-specific.
o Includes:
§ Physical barriers (skin, mucous)
§ Physiological barriers (acid,
saliva)
§ Cellular barriers (macrophages)
§ Cytokine barriers (interferons)
2.
Acquired
Immunity:
o Specific, develops after
infection/vaccination.
o Active Immunity: Antibody production after infection
or vaccine.
o Passive Immunity: Ready-made antibodies (mother’s
milk, antiserum).
Q4. Describe the structure of an
antibody molecule with a labeled diagram.
Answer:
- Y-shaped molecule composed of two
heavy and two light chains linked by disulfide bonds.
- Variable region (Fab): Binds to antigen.
- Constant region (Fc): Determines antibody class
(IgG, IgA, etc.).
- Each antibody has two
antigen-binding sites.
Function: Neutralizes toxins, agglutinates pathogens, activates complement system.
Q5. What is vaccination? Explain the
principle of vaccination and give examples.
Answer:
Vaccination: Process of introducing attenuated/killed pathogens to
produce immunity.
Principle:
- Based on the formation of memory
cells during primary immune response.
- On subsequent infection, secondary
response is faster and stronger.
Examples: - BCG – Tuberculosis
- DPT – Diphtheria, Pertussis,
Tetanus
- OPV – Polio
- Hepatitis-B vaccine –
Recombinant DNA vaccine.
Importance: Prevents epidemics, eradicated smallpox globally.
Q6. Explain how the immune system
responds to infection.
Answer:
1.
Recognition: Antigen recognized by B and T
lymphocytes.
2.
Activation: Helper T-cells release cytokines
stimulating B-cells and cytotoxic T-cells.
3.
Effector
phase:
o B-cells form plasma cells → produce
antibodies.
o Cytotoxic T-cells destroy infected cells.
4.
Memory
formation: Memory B
and T-cells persist for faster secondary response.
Q7. What are allergens? Describe
allergic response and its treatment.
Answer:
- Allergens are normally harmless
substances (pollen, dust, mites) that trigger immune hypersensitivity.
Mechanism:
1.
Allergen
induces IgE antibody formation.
2.
IgE
binds to mast cells → release histamine, serotonin.
3.
Causes
inflammation, itching, sneezing, rashes.
Treatment:
- Use of antihistamines, steroids,
and avoiding allergens.
- Desensitization therapy through small doses of
allergen.
Q8. What is autoimmune disease?
Explain with examples and its effects.
Answer:
- When immune system attacks
self-tissues.
Examples:
1.
Type-1
Diabetes: β-cells
of pancreas destroyed → insulin deficiency.
2.
Rheumatoid
arthritis: Joints
inflamed.
3.
Multiple
sclerosis: Nerve
sheath damaged.
Effects: Tissue damage, chronic inflammation, organ failure.
Treatment: Immunosuppressive drugs.
Q9. Describe the life cycle of Plasmodium
vivax in humans and mosquitoes.
Answer:
1.
In
Human (Asexual cycle):
o Sporozoites injected by female Anopheles
→ infect liver cells → merozoites.
o Merozoites infect RBCs →
trophozoites → schizonts → rupture RBCs → chills & fever.
o Some form gametocytes.
2.
In
Mosquito (Sexual cycle):
o Gametocytes ingested → fertilization
→ ookinete → oocyst → sporozoites → migrate to salivary glands.
Diagram: Label liver, RBC, mosquito gut stages.
Q10. Write short notes on (i)
Typhoid (ii) Pneumonia.
Answer:
(i) Typhoid:
- Causative agent: Salmonella
typhi.
- Symptoms: Fever, headache,
intestinal ulcers.
- Spread: Contaminated
food/water.
- Prevention: Proper sanitation,
Typhoid vaccine.
(ii) Pneumonia: - Causative agents: Streptococcus
pneumoniae, Haemophilus influenzae.
- Symptoms: Fever, cough, chest
pain, breathlessness.
- Spread: Droplet infection.
- Prevention: Pneumococcal
vaccine.
Q11. Explain the symptoms, cause,
transmission, and prevention of Amoebiasis.
Answer:
- Causative agent: Entamoeba histolytica.
- Transmission: Fecal-oral route via
contaminated food/water.
- Symptoms: Abdominal pain, cramping,
dysentery with blood and mucus.
- Prevention: Proper sanitation, clean
water, personal hygiene.
Q12. What is AIDS? Explain its causative
organism, symptoms, transmission, and prevention.
Answer:
- AIDS: Acquired Immuno Deficiency
Syndrome.
- Causative virus: HIV (Human Immunodeficiency
Virus).
Symptoms: Weight loss, fatigue, prolonged fever, opportunistic infections (TB, pneumonia).
Transmission: Unprotected sex, blood transfusion, contaminated needles, mother-to-child.
Prevention: Safe sex, screened blood, sterile syringes, education, awareness.
Q13. Explain the mechanism of action
of HIV in the human body.
Answer:
1.
HIV
targets CD4 T-cells.
2.
Viral
RNA → DNA by reverse transcriptase.
3.
Viral
DNA integrates with host genome.
4.
Infected
cells produce more viruses → destroy helper T-cells.
5.
Immunity
declines → body susceptible to other infections.
Q14. What are cancer and
carcinogens? Explain metastasis and preventive measures.
Answer:
- Cancer: Uncontrolled proliferation of
cells forming malignant tumors.
- Carcinogens: Substances causing cancer
(chemicals, radiation, viruses).
- Metastasis: Spread of cancerous cells to
distant organs through blood/lymph.
Prevention: Avoid tobacco, alcohol; healthy diet; regular screening; vaccination (HPV, HBV).
Q15. Describe the types and
properties of cancer cells.
Answer:
- Lose control of division → form
tumors.
Types:
1.
Benign: Localized, non-invasive.
2.
Malignant: Invade tissues, metastasize.
Properties:
- No contact inhibition.
- High growth rate.
- Angiogenesis (new blood
vessels).
- Genetic instability.
Q16. How is cancer diagnosed and
treated?
Answer:
Diagnosis:
- Imaging (CT, MRI, PET, Biopsy).
- Tumor markers.
Treatment:
1.
Surgery: Removal of tumor.
2.
Radiotherapy: Radiation to kill cells.
3.
Chemotherapy: Anti-cancer drugs.
4.
Immunotherapy: Interferons, antibodies stimulate
immune system.
Q17. Write a note on Adolescence
and Drug Abuse.
Answer:
- Adolescence = transitional
stage (12–18 yrs).
- Curiosity, stress, peer
pressure may lead to drug/alcohol use.
- Common drugs: Opioids (heroin), cannabinoids
(marijuana), cocaine.
- Effects: Mental disorders, liver
damage, addiction, social problems.
- Prevention: Counseling, education,
positive peer group, healthy hobbies.
Q18. Explain the causes, symptoms,
and preventive measures of drug abuse.
Answer:
Causes: Peer pressure, curiosity, stress, lack of confidence.
Symptoms: Change in behavior, isolation, weight loss, insomnia.
Prevention: Education, parental care, awareness campaigns,
rehabilitation centers.
Q19. Compare the effects of alcohol
and drugs on the nervous system.
Answer:
|
Feature |
Alcohol |
Drugs |
|
Type |
Depressant |
Stimulant/Depressant |
|
Effect |
Slows CNS, impairs coordination |
Alters brain function |
|
Long-term |
Liver cirrhosis, heart problems |
Addiction, hallucination, brain damage |
Q20. Explain the role of
rehabilitation in drug-addict recovery.
Answer:
- Medical therapy: Detoxification and medication.
- Psychological therapy: Counseling, behavioral
therapy.
- Social support: Family, peers, community
groups.
- Occupational therapy: Helps regain confidence and
employability.
Q21. What are the main steps in
controlling infectious diseases in society?
Answer:
1.
Immunization
programs (e.g.,
Universal Immunization).
2.
Public
health measures
– sanitation, clean water, waste disposal.
3.
Vector
control –
insecticides, mosquito nets.
4.
Health
education –
awareness campaigns.
5.
Surveillance
and early diagnosis.
Q22. Explain why adolescents are
more vulnerable to drug and alcohol abuse.
Answer:
- Peer pressure, curiosity, easy
availability, stress, lack of guidance.
- Adolescents are emotionally
unstable and seek new experiences.
- Lack of parental supervision
enhances risk.
Prevention: Parental support, healthy hobbies, counseling in schools.
Q23. Describe the role of lymphoid
organs in the immune system.
Answer:
- Primary lymphoid organs:
- Bone marrow: Produces all lymphocytes;
B-cells mature here.
- Thymus: T-cells mature here.
- Secondary lymphoid organs:
- Lymph nodes, spleen, tonsils,
Peyer’s patches.
- Function: Trap antigens,
provide sites for interaction between lymphocytes and antigens.
Q24. Explain how antibodies act to
neutralize antigens.
Answer:
1.
Neutralization: Bind to toxins or viruses,
preventing their entry.
2.
Agglutination: Clump pathogens for phagocytosis.
3.
Precipitation: Soluble antigens converted to
insoluble complexes.
4.
Complement
activation:
Leads to lysis of pathogens.
Q25. Describe the preventive and
control measures for vector-borne diseases like malaria and dengue.
Answer:
- Eliminate breeding sites: Drain stagnant water.
- Use insecticides and
larvicides.
- Personal protection: Mosquito nets, repellents.
- Biological control: Fish (Gambusia) eat larvae.
- Public awareness programs: Promote cleanliness and early
treatment.
Q1. Explain the role of the immune
system in maintaining human health. Describe its types and components.
Answer:
The immune system defends the body from pathogens and foreign substances.
It includes organs like thymus, bone marrow, spleen, lymph nodes, and WBCs.
Types of Immunity:
1.
Innate
Immunity:
o Present from birth; non-specific.
o Barriers:
§ Physical (skin, mucous membranes)
§ Physiological (acid in stomach,
saliva)
§ Cellular (phagocytes, NK cells)
§ Cytokine barriers (interferons)
2.
Acquired
Immunity:
o Develops after exposure to antigens.
o Humoral Immunity: B-cells produce antibodies.
o Cell-mediated Immunity: T-cells destroy infected cells.
Conclusion:
Both systems work together to maintain health by recognizing and destroying
harmful invaders.
Q2. Describe the structure of HIV and
explain the mechanism of infection and its effect on the human body.
Answer:
Structure:
- HIV (Human Immunodeficiency
Virus) is an RNA retrovirus.
- Contains RNA genome, reverse
transcriptase enzyme, and surrounded by an envelope made of lipids and glycoproteins
(gp120).
Mechanism of Infection:
1.
Virus
binds to CD4 receptors on helper T-cells.
2.
RNA
is converted to DNA by reverse transcriptase.
3.
Viral
DNA integrates into host genome (provirus).
4.
New
viruses are produced and released.
Effect:
- Gradual depletion of helper
T-cells weakens immunity.
- The patient becomes prone to
infections like pneumonia, tuberculosis, and cancers (AIDS).
Q3. Discuss the life cycle of Plasmodium
vivax in humans and mosquitoes.
Answer:
1. In Humans (Asexual phase):
- Infection through bite of
infected female Anopheles mosquito.
- Sporozoites enter bloodstream → liver →
form merozoites.
- Merozoites infect RBCs →
multiply → cause RBC rupture → release toxins → fever/chills.
2. In Mosquito (Sexual phase):
- Mosquito ingests gametocytes
from human blood.
- In stomach → fertilization →
zygote → ookinete → oocyst.
- Oocyst releases sporozoites
that migrate to salivary glands.
Cycle continues when mosquito bites another human.
Q4. Describe the causes, symptoms,
and prevention of Typhoid and Pneumonia.
Answer:
(A) Typhoid:
- Causative agent: Salmonella typhi
- Transmission: Contaminated food and water.
- Symptoms: Prolonged fever, headache,
constipation, abdominal pain, intestinal perforation.
- Diagnosis: Widal test.
- Prevention: Proper sanitation,
vaccination, clean drinking water.
(B) Pneumonia:
- Causative agent: Streptococcus pneumoniae
/ Haemophilus influenzae
- Transmission: Droplet infection.
- Symptoms: Fever, chills, cough,
breathing difficulty.
- Prevention: Avoid crowding, vaccination, good
hygiene.
Q5. Explain how allergies and
autoimmune diseases differ. Give examples.
Answer:
|
Feature |
Allergy |
Autoimmune Disease |
|
Definition |
Hypersensitivity to harmless substances |
Immune system attacks body’s own cells |
|
Mechanism |
IgE-mediated histamine release |
Self-reactive T or B cells |
|
Examples |
Asthma, hay fever, drug allergy |
Rheumatoid arthritis, Type 1 diabetes, Multiple sclerosis |
|
Symptoms |
Sneezing, rash, swelling |
Tissue destruction, inflammation |
|
Treatment |
Antihistamines |
Immunosuppressive drugs |
Q6. What is cancer? Explain its
types, causes, and treatment methods.
Answer:
Cancer is uncontrolled cell division leading to tumor formation.
Types:
1.
Benign: Localized, non-spreading.
2.
Malignant: Invades nearby tissues and spreads
(metastasis).
Causes:
- Carcinogens (chemicals,
radiation, viruses)
- Genetic mutations
- Lifestyle (smoking, diet)
Treatment:
- Surgery: Removes tumor.
- Radiotherapy: Destroys cells by radiation.
- Chemotherapy: Drugs to kill cancer cells.
- Immunotherapy: Boosts immune attack on
cancer.
Q7. Differentiate between active and
passive immunity with examples.
Answer:
|
Feature |
Active Immunity |
Passive Immunity |
|
Source |
Body produces antibodies |
Ready-made antibodies given |
|
Duration |
Long-lasting |
Short-lived |
|
Onset |
Slow |
Immediate |
|
Example |
Vaccination, infection recovery |
Colostrum antibodies, serum injection |
Q8. Explain the principle and
importance of vaccination. Give examples of vaccines.
Answer:
Principle:
Vaccination exposes the body to weakened/dead pathogens → stimulates immune
memory without causing disease.
Importance:
- Prevents diseases (individual
and herd immunity).
- Eradicates diseases (e.g.,
smallpox).
Examples:
- BCG (Tuberculosis)
- DPT (Diphtheria, Pertussis,
Tetanus)
- OPV (Polio)
- Hepatitis-B vaccine
Q9. Discuss the main approaches to
control and prevent drug and alcohol abuse among youth.
Answer:
1. Education and Awareness:
Inform students about harmful effects.
2. Counselling:
Help addicted individuals recover emotionally.
3. Parental Support:
Healthy family environment prevents curiosity use.
4. Peer Pressure Management:
Teach assertiveness and refusal skills.
5. Rehabilitation Centers:
Provide medical and psychological support.
Q10. What are the major bacterial
diseases in humans? Write their symptoms and prevention.
Answer:
|
Disease |
Pathogen |
Symptoms |
Prevention |
|
Typhoid |
Salmonella typhi |
Fever, constipation |
Hygiene, vaccination |
|
Pneumonia |
Streptococcus pneumoniae |
Breathing difficulty |
Avoid crowding |
|
Diphtheria |
Corynebacterium diphtheriae |
Throat membrane |
DPT vaccine |
|
Tuberculosis |
Mycobacterium tuberculosis |
Cough with blood |
BCG vaccine |
Q11. Explain the role of interferons
in viral infection.
Answer:
- Interferons are antiviral proteins
produced by virus-infected cells.
- They prevent multiplication of
viruses in neighboring cells.
- Enhance activity of macrophages
and NK cells.
- Used in treatment of viral
infections and cancer.
Q12. Describe the preventive
measures for vector-borne diseases.
Answer:
- Use mosquito nets, repellents.
- Eliminate stagnant water.
- Insecticide sprays.
- Cover body parts.
- Vaccination (where available).
Examples: Malaria, dengue, filariasis.
Q13. What are the different types of
immunity barriers in the human body?
Answer:
1.
Physical
barriers: Skin,
mucous membrane.
2.
Physiological
barriers: HCl in
stomach, saliva, tears.
3.
Cellular
barriers:
Phagocytes, NK cells.
4.
Cytokine
barriers:
Interferons.
Q14. Explain the life cycle of Wuchereria
bancrofti (filariasis).
Answer:
- Transmitted by female Culex
mosquito.
- Larvae enter human lymphatic
vessels → mature → cause inflammation.
- Leads to swelling of limbs
(elephantiasis).
- Mosquito picks microfilariae →
develops infective larvae → spreads.
Q15. What is immunisation? Describe
types of vaccines with examples.
Answer:
Immunisation: Process of developing immunity by vaccination or
infection.
Types of Vaccines:
1.
Live
attenuated:
BCG, polio (Sabin).
2.
Killed: Cholera, typhoid.
3.
Toxoid: Diphtheria, tetanus.
4.
Recombinant: Hepatitis B.
Q16. Describe the symptoms, cause,
and prevention of ringworm.
Answer:
- Cause: Fungi (Microsporum,
Trichophyton, Epidermophyton).
- Symptoms: Circular itchy patches on
skin/scalp.
- Transmission: Contact with infected person
or objects.
- Prevention: Keep dry, personal hygiene,
antifungal treatment.
Q17. What are the major effects of
alcohol abuse on the body?
Answer:
- Liver damage (cirrhosis)
- Brain impairment
- Loss of coordination
- Addiction and depression
- Social and financial issues
Q18. Explain how pathogens enter the
human body and cause disease.
Answer:
- Entry routes: Mouth, nose, skin wounds,
sexual contact.
- Mechanisms:
- Damage tissues directly.
- Release toxins (e.g.,
bacteria).
- Multiply and destroy cells
(e.g., viruses).
- Immune response: Fever, inflammation, antibody
production.
Q19. Describe malaria prevention and
control measures.
Answer:
1.
Vector
control:
Insecticides, remove stagnant water.
2.
Personal
protection:
Nets, repellents.
3.
Chemoprophylaxis: Antimalarial drugs (chloroquine).
4.
Early
diagnosis and treatment.
Q20. Explain the difference between
infection and disease with examples.
Answer:
|
Infection |
Disease |
|
Entry and multiplication of pathogen |
Condition with symptoms |
|
May be symptomless |
Causes functional disturbance |
|
Example: HIV infection |
Example: AIDS |
Q21. Describe the three types of
barriers in innate immunity.
Answer:
1.
Physical
Barriers: Skin,
mucosa.
2.
Physiological
Barriers: HCl,
tears, saliva.
3.
Cellular
Barriers:
Phagocytes, NK cells.
Q22. Explain the term ‘antibody’ and
its function.
Answer:
- Antibody (Immunoglobulin): Protein produced by B-cells in
response to antigen.
- Function:
- Neutralize toxins.
- Agglutinate pathogens.
- Activate complement system.
- Provide memory response.
Q23. What is the difference between
vaccination and immunisation?
Answer:
|
Vaccination |
Immunisation |
|
Process of giving vaccine |
Development of immunity |
|
External step |
Internal outcome |
|
Example: BCG injection |
Immunity against TB |
Q24. Describe the structure and
function of lymphatic system in immunity.
Answer:
- Components: Lymph, lymph nodes, lymph
vessels, spleen, thymus.
- Functions:
- Transport lymphocytes.
- Filter pathogens.
- Maintain tissue fluid balance.
- Aid in immune response.
Q25. What are the preventive and
control measures for AIDS?
Answer:
- Avoid unprotected sex.
- Use sterile needles and
syringes.
- Screen blood before
transfusion.
- Avoid sharing razors/blades.
- Awareness programs (NACO, WHO).
