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CBSE · NCERT
BIOLOGY – CHAPTER 7 : HUMAN HEALTH AND DISEASE
Chapter-wise Practice Question Paper (Board + Competitive / NEET Level)
General Instructions
- All questions are compulsory. This paper is based on NCERT Class XII Biology, Chapter 7, and includes NEET-style MCQs and Assertion–Reason questions.
- Q.1 to Q.5 are Section A (40 marks): Q.1 has 20 MCQs; Q.2, Q.3, Q.4 and Q.5 have 5 questions each; every question carries 1 mark.
- Q.6 to Q.13 carry 2 marks each; Q.14 to Q.20 carry 3 marks each; Q.21 and Q.22 are case-based questions of 4 marks each; Q.23 to Q.25 carry 5 marks each.
- Internal choice (OR) is given in Q.14 to Q.20 and Q.23 to Q.25. Attempt only one of the alternatives.
- Draw neat, labelled diagrams wherever required. Solutions to all questions are given after the paper.
SECTION – A (Objective Questions · 40 Marks)
Q.1 Choose the correct option.20 × 1 = 20
(i) The Widal test is used for the diagnosis of –
(a) Typhoid(b) Malaria(c) AIDS(d) Cancer
(ii) The most serious and fatal form of malaria (malignant malaria) is caused by –
(a) Plasmodium vivax(b) Plasmodium malariae(c) Plasmodium falciparum(d) Entamoeba histolytica
(iii) The infective stage of Plasmodium that is injected into the human body by the female Anopheles is the –
(a) Merozoite(b) Gametocyte(c) Trophozoite(d) Sporozoite
(iv) The toxin responsible for the periodic chill and high fever in malaria is –
(a) Interferon(b) Haemozoin(c) Histamine(d) Nicotine
(v) Pneumonia in humans is caused by –
(a) Streptococcus pneumoniae and Haemophilus influenzae(b) Rhinoviruses(c) Plasmodium(d) Entamoeba
(vi) Rhinoviruses that cause the common cold infect –
(a) The lungs and alveoli(b) The intestine(c) The nose and respiratory passage but not the lungs(d) The liver
(vii) Wuchereria bancrofti, the cause of filariasis, is transmitted by –
(a) Female Anopheles(b) Aedes(c) Housefly(d) Female Culex
(viii) Entamoeba histolytica infects the –
(a) Liver(b) Large intestine(c) Lungs(d) Lymph vessels
(ix) Ringworm is caused by –
(a) Fungi (Microsporum, Trichophyton, Epidermophyton)(b) Bacteria(c) Protozoa(d) Helminths
(x) Which of the following is a physiological barrier of innate immunity?
(a) Skin(b) Neutrophils(c) Acid in the stomach(d) Interferons
(xi) Interferons, secreted by virus-infected cells, form the –
(a) Physical barrier(b) Physiological barrier(c) Cellular barrier(d) Cytokine barrier
(xii) Antibody-mediated (humoral) immune response is carried out by –
(a) T-lymphocytes(b) B-lymphocytes(c) Natural killer cells(d) Macrophages
(xiii) An antibody molecule is made up of –
(a) Two heavy and two light chains (H2L2)(b) Four heavy chains(c) One heavy and one light chain(d) Three heavy and three light chains
(xiv) The antibodies present in colostrum, which protect the infant, are –
(a) IgE(b) IgM(c) IgA(d) IgD
(xv) Which of the following is a secondary lymphoid organ?
(a) Thymus(b) Bone marrow(c) Pancreas(d) Spleen
(xvi) HIV is –
(a) A DNA virus(b) A retrovirus with an RNA genome(c) A bacterium(d) A protozoan
(xvii) In an AIDS patient, the number of which cells decreases significantly?
(a) Helper T-lymphocytes (TH)(b) B-lymphocytes(c) Red blood cells(d) Platelets
(xviii) The standard diagnostic test for AIDS is –
(a) Widal test(b) Biopsy(c) ELISA(d) MRI
(xix) Cancer cells have lost –
(a) Respiration(b) DNA(c) The nucleus(d) Contact inhibition
(xx) Heroin (smack) is chemically diacetylmorphine, obtained by acetylation of –
(a) Cocaine(b) Morphine(c) Nicotine(d) Cannabinoids
Q.2 Fill in the blanks.5 × 1 = 5
(i) The disease caused by the filarial worm Wuchereria is ______.
(ii) In malaria, the female Anopheles mosquito acts as the ______ of the parasite.
(iii) Antibodies are secreted by ______.
(iv) Heroin is chemically ______.
(v) The spread of malignant tumour cells to distant sites is called ______.
Q.3 Write True or False.5 × 1 = 5
(i) Pneumonia is an infection of the alveoli of the lungs.
(ii) Active immunity is quick and gives no memory.
(iii) HIV spreads through a handshake or casual contact with an infected person.
(iv) The thymus is a primary lymphoid organ.
(v) Benign tumours spread to distant sites by metastasis.
Q.4 Match Column ‘A’ with Column ‘B’.5 × 1 = 5
| Column ‘A’ | Column ‘B’ |
|---|---|
| (i) Plasmodium | (a) Elephantiasis |
| (ii) Entamoeba histolytica | (b) Pneumonia |
| (iii) Wuchereria | (c) Malaria |
| (iv) Trichophyton | (d) Ringworm |
| (v) Haemophilus influenzae | (e) Amoebiasis |
Q.5 Assertion (A) – Reason (R) type questions. Choose: (a) Both A and R true, R explains A; (b) Both true, R does not explain A; (c) A true, R false; (d) A false, R true.5 × 1 = 5
(i) Assertion (A): Colostrum is important for the newborn baby.
Reason (R): Colostrum contains IgA antibodies that provide passive immunity.
Reason (R): Colostrum contains IgA antibodies that provide passive immunity.
(ii) Assertion (A): In HIV infection the number of helper T-cells decreases.
Reason (R): AIDS is diagnosed by the ELISA test.
Reason (R): AIDS is diagnosed by the ELISA test.
(iii) Assertion (A): Interferons are secreted by virus-infected cells.
Reason (R): Interferons directly kill the viruses inside infected cells.
Reason (R): Interferons directly kill the viruses inside infected cells.
(iv) Assertion (A): Benign tumours spread to other parts of the body.
Reason (R): Malignant tumours show metastasis.
Reason (R): Malignant tumours show metastasis.
(v) Assertion (A): Vaccination protects against infectious diseases.
Reason (R): A vaccine contains antigens (weakened/inactivated pathogens) that produce memory B- and T-cells.
Reason (R): A vaccine contains antigens (weakened/inactivated pathogens) that produce memory B- and T-cells.
SECTION – B (Very Short Answer · 2 Marks each)
6. Differentiate between active and passive immunity.(2)
7. Name the causative agents of typhoid and pneumonia. Name the test used to confirm typhoid.(2)
8. Why is the life cycle of Plasmodium said to need two hosts? Name them.(2)
9. What is allergy? Name two allergens and the chemicals released during an allergic reaction.(2)
10. What are primary lymphoid organs? State the role of the thymus.(2)
11. Mention any two ways by which HIV is transmitted. Which cells does it first infect?(2)
12. Differentiate between benign and malignant tumours.(2)
13. What is addiction? What is meant by withdrawal syndrome?(2)
SECTION – C (Short Answer · 3 Marks each)
14. Describe the life cycle of Plasmodium in humans and the mosquito.(3)
OR
Describe amoebiasis, ascariasis and filariasis – causative organisms, symptoms and transmission.
15. Describe the four types of barriers in innate immunity.(3)
OR
Describe the structure of an antibody. Name the different types of antibodies.
16. Distinguish between the primary and secondary immune responses.(3)
OR
What is vaccination? Explain the principle of immunisation and the role of recombinant DNA technology.
17. What are allergies and autoimmune diseases? Give one example of each and state the treatment of allergy.(3)
OR
Describe the lymphoid organs of the human immune system and their functions.
18. What is AIDS? Write the mode of transmission and preventive measures.(3)
OR
Explain how HIV replicates in the human body and leads to AIDS.
19. Describe the causes, detection and treatment of cancer.(3)
OR
Describe the types of carcinogens and the role of oncogenes in cancer.
20. Describe the sources and effects of opioids, cannabinoids and cocaine.(3)
OR
Describe the harmful effects of tobacco and alcohol. What is ‘doping’?
SECTION – D (Case-Based Questions · 4 Marks each)
21. Read the passage and answer the questions that follow.(4)
A patient comes to a clinic with chills and high fever that recur every 3–4 days. A blood smear shows a parasite inside red blood cells. The doctor says that the infection was transmitted by the bite of a female mosquito.
(i) Name the parasite that causes the most serious form of this disease, and its vector.(1)
(ii) Name the toxin responsible for the recurring fever and its source.(1)
(iii) Name the stage that enters the human body with the mosquito bite and the organ where it first multiplies. Suggest two measures to control the disease.(2)
22. Read the passage and answer the questions that follow.(4)
A newborn baby is breast-fed and gets antibodies from the mother’s first milk. At 6 weeks the baby is given the DPT vaccine. Later a child bitten by a snake is given antivenom injection.
(i) Name the type of immunity provided by the mother’s first milk and the antibody class involved.(1)
(ii) Which type of immunity is provided by the DPT vaccine? Why does it protect for a long time?(1)
(iii) Why is the antivenom said to give passive immunity? Differentiate it from active immunity in terms of time of action and memory.(2)
SECTION – E (Long Answer · 5 Marks each)
23. Describe the common infectious diseases typhoid, pneumonia, common cold and malaria – cause, symptoms and mode of transmission.(5)
OR
Describe amoebiasis, ascariasis, filariasis, ringworm and dengue/chikungunya – cause, symptoms, transmission and preventive measures.
24. Explain the innate and acquired immune responses, including the roles of B- and T-lymphocytes (humoral and cell-mediated immunity).(5)
OR
Describe AIDS (cause, replication of HIV, transmission, diagnosis, prevention) and cancer (types of tumour, causes, treatment).
25. Describe drug and alcohol abuse in adolescents: the commonly abused drugs, effects, addiction and dependence, and the measures for prevention and control.(5)
OR
Describe the lymphoid organs of the human immune system, and write short notes on allergy, autoimmunity and tissue/organ transplantation.
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CBSE · NCERT
BIOLOGY – CHAPTER 7 : COMPLETE SOLUTIONS
Human Health and Disease · Answer Key with Step-by-Step Explanations
Q.1 Quick Answer Key (MCQ)20 × 1 = 20
| i | (a) | ii | (c) | iii | (d) | iv | (b) | v | (a) |
| vi | (c) | vii | (d) | viii | (b) | ix | (a) | x | (c) |
| xi | (d) | xii | (b) | xiii | (a) | xiv | (c) | xv | (d) |
| xvi | (b) | xvii | (a) | xviii | (c) | xix | (d) | xx | (b) |
Q.1 Solutions with Explanation
(i) Ans. (a) Typhoid
Widal test is a diagnostic test for typhoid fever caused by Salmonella typhi (a bacterium).
(ii) Ans. (c) Plasmodium falciparum
P. vivax and P. malariae cause milder forms; P. falciparum causes malignant malaria, which can be fatal.
(iii) Ans. (d) Sporozoite
Sporozoites are injected with the saliva of the mosquito; they multiply in the liver cells and then attack RBCs as merozoites.
(iv) Ans. (b) Haemozoin
When infected RBCs rupture, a toxic substance called haemozoin is released, causing chill and high fever recurring every 3–4 days.
(v) Ans. (a) Streptococcus pneumoniae and Haemophilus influenzae
These bacteria infect the alveoli of the lungs, which get filled with fluid; lips and fingernails may turn greyish to bluish in severe cases.
(vi) Ans. (c) The nose and respiratory passage but not the lungs
Common cold affects the nose and respiratory passage but not the lungs; it lasts 3–7 days.
(vii) Ans. (d) Female Culex
Filarial worms infect the lymphatic vessels (causing elephantiasis) and are transmitted by Culex mosquitoes.
(viii) Ans. (b) Large intestine
It causes amoebiasis (amoebic dysentery) in the large intestine; houseflies act as mechanical carriers.
(ix) Ans. (a) Fungi (Microsporum, Trichophyton, Epidermophyton)
Dry, scaly lesions on skin, nails and scalp with intense itching; transmitted by soil or by using towels, clothes and combs of infected persons.
(x) Ans. (c) Acid in the stomach
Physiological barriers: gastric acid, saliva in the mouth, tears from the eyes. Skin is a physical barrier; neutrophils are cellular; interferons are cytokine barriers.
(xi) Ans. (d) Cytokine barrier
Virus-infected cells secrete interferons, which protect non-infected cells from further viral infection (cytokine barrier).
(xii) Ans. (b) B-lymphocytes
B-lymphocytes produce an army of proteins (antibodies) in the blood; T-cells are responsible for cell-mediated immunity (CMI).
(xiii) Ans. (a) Two heavy and two light chains (H2L2)
Each antibody has two light and two heavy polypeptide chains (H2L2); types: IgA, IgM, IgE, IgG.
(xiv) Ans. (c) IgA
Colostrum contains abundant IgA antibodies – passive immunity. IgG crosses the placenta to the foetus.
(xv) Ans. (d) Spleen
Bone marrow and thymus are primary lymphoid organs (lymphocytes mature); spleen, lymph nodes, tonsils, Peyer’s patches, appendix and MALT are secondary.
(xvi) Ans. (b) A retrovirus with an RNA genome
HIV is a retrovirus: it uses reverse transcriptase to make viral DNA from its RNA, which integrates into the host DNA.
(xvii) Ans. (a) Helper T-lymphocytes (TH)
HIV infects macrophages and helper T-cells; their number declines, so the patient becomes immunodeficient and susceptible to opportunistic infections.
(xviii) Ans. (c) ELISA
ELISA (enzyme-linked immuno-sorbent assay) is used for HIV diagnosis.
(xix) Ans. (d) Contact inhibition
Normal cells show contact inhibition (growth stops on contact with other cells); cancer cells lose it and divide uncontrollably, forming a tumour.
(xx) Ans. (b) Morphine
Morphine is extracted from the latex of the poppy plant Papaver somniferum; acetylation gives heroin, a depressant.
Q.2 Fill in the blanks5 × 1 = 5
(i) Filariasis (elephantiasis)
(ii) Vector
(iii) B-lymphocytes (plasma cells)
(iv) Diacetylmorphine
(v) Metastasis
Q.3 True / False5 × 1 = 5
(i) True.
Streptococcus pneumoniae and Haemophilus influenzae infect the alveoli, which fill with fluid.
(ii) False.
Active immunity is slow (takes time) but long-lasting with memory; passive immunity is quick but short-lived.
(iii) False.
HIV spreads only by sexual contact, contaminated blood/needles and from an infected mother to her child; not by touch or sharing normal contact.
(iv) True.
T-lymphocytes mature in the thymus; B-cells and T-cells originate in bone marrow.
(v) False.
Benign tumours remain confined to their site of origin; malignant tumours show metastasis.
Q.4 Matching5 × 1 = 5
(i) – (c) · (ii) – (e) · (iii) – (a) · (iv) – (d) · (v) – (b)
Plasmodium – malaria; Entamoeba histolytica – amoebiasis; Wuchereria – elephantiasis; Trichophyton – ringworm; Haemophilus influenzae – pneumonia.
Q.5 Assertion – Reason5 × 1 = 5
(i) Ans. (a)
Both true; the antibodies in colostrum give the infant resistance.
(ii) Ans. (b)
Both true but R does not explain A.
(iii) Ans. (c)
A is true. R is false: interferons protect the neighbouring non-infected cells from viral infection.
(iv) Ans. (d)
A is false: benign tumours remain localised. R is true.
(v) Ans. (a)
Both true; the memory cells give a quick and strong secondary response on actual infection.
SECTION – B (2 Marks each)
6. Ans.
| Active immunity | Passive immunity |
|---|---|
| Host’s own cells produce antibodies on exposure to antigens (infection/vaccine) | Ready-made antibodies are given to the host (colostrum, injection of antivenom) |
| Slow, takes time; long-lasting with memory | Quick, short-lived; no memory |
7. Ans.
Typhoid: Salmonella typhi. Pneumonia: Streptococcus pneumoniae and Haemophilus influenzae. [1] Typhoid is confirmed by the Widal test. [1]
8. Ans.
Plasmodium completes its asexual stages (in liver cells and RBCs) in the human and the sexual stages (gametocytes → fertilisation → sporozoites) in the female Anopheles mosquito. [1] The mosquito is the vector (and definitive host), humans are the intermediate host. [1]
9. Ans.
Allergy is an exaggerated response of the immune system to certain antigens (allergens) present in the environment; antibodies produced are of the IgE type. [1] Allergens: dust mites, pollen, animal dander. Mast cells release histamine and serotonin. [1]
10. Ans.
The primary lymphoid organs are the bone marrow and thymus, where immature lymphocytes differentiate into antigen-sensitive lymphocytes. [1] The thymus is where T-lymphocytes mature; it is large at birth and reduces in size with age. [1]
11. Ans.
(i) Sexual contact with an infected person; (ii) transfusion of contaminated blood/blood products; (iii) sharing of infected needles; (iv) from an infected mother to the child through the placenta. (Any two, ½ each) [1] HIV first enters macrophages and then infects helper T-lymphocytes. [1]
12. Ans.
| Benign tumour | Malignant tumour |
|---|---|
| Confined to the place of origin | Spreads to other sites by metastasis |
| Normally causes little damage | Neoplastic cells grow rapidly, invade and damage tissues |
13. Ans.
Addiction is a psychological attachment to the effects of a drug/alcohol (the euphoria and a temporary feeling of well-being) with a craving to repeat its use and tolerance to it. [1] Withdrawal syndrome: the characteristic, often severe symptoms (anxiety, shakiness, nausea, sweating) that appear when the regular dose of the drug or alcohol is abruptly stopped. [1]
SECTION – C (3 Marks each)
14. Ans.
In humans: the female Anopheles injects sporozoites into the blood; they multiply in liver cells and then attack RBCs as merozoites, which multiply and cause rupture of RBCs, releasing haemozoin – chill and high fever recurring every 3–4 days. [1½] Some parasites develop into gametocytes in RBCs. [½] In mosquito: a mosquito biting an infected person takes up the gametocytes; they fertilise and develop in the gut, forming sporozoites that migrate to the salivary glands, from where they are injected into another human. [1]
OR
Amoebiasis: Entamoeba histolytica in the large intestine; constipation, abdominal pain, cramps, stools with mucus and blood clots; transmitted by contaminated food and water (houseflies are mechanical carriers). [1] Ascariasis: roundworm Ascaris; internal bleeding, muscular pain, fever, anaemia and blockage of the intestine; eggs excreted with the faeces contaminate soil, water and plants. [1] Filariasis: Wuchereria bancrofti / W. malayi in the lymphatic vessels of the lower limbs; chronic inflammation, elephantiasis, genital deformities; transmitted by the female Culex mosquito. [1]
15. Ans.
Innate immunity is non-specific and present at birth. 1. Physical barriers: skin, mucus coating of the respiratory, gastrointestinal and urogenital tracts which traps microbes. 2. Physiological barriers: gastric acid, saliva, tears. 3. Cellular barriers: neutrophils (PMNL), monocytes, natural killer lymphocytes and macrophages that phagocytose microbes. 4. Cytokine barriers: interferons secreted by virus-infected cells protect non-infected cells. [¾ × 4]
OR
An antibody is a Y-shaped protein with four peptide chains – two small light chains and two longer heavy chains (H2L2); the antigen-binding sites are at the tips. [2] Types: IgA, IgM, IgE, IgG (IgG crosses the placenta; IgA is found in colostrum; IgE is involved in allergy). [1]
16. Ans.
| Primary response | Secondary (anamnestic) response |
|---|---|
| First encounter with the pathogen | Subsequent encounter with the same pathogen |
| Low intensity, slow | Highly intensified, quick |
| Memory cells are formed | Due to memory B- and T-cells |
OR
Vaccination: introducing inactivated/weakened pathogens (or their proteins) as antigens into the body, which produce antibodies and memory B- and T-cells, so that on actual infection a quick, strong response occurs. [1½] Principle: memory of the immune system (Edward Jenner’s smallpox vaccine; polio, DPT, tetanus toxoid). [½] Recombinant DNA technology: a vaccine antigen (e.g. hepatitis-B vaccine) is produced in bacteria or yeast. [1]
17. Ans.
Allergy: exaggerated response to allergens such as pollen and dust mites; IgE antibodies and release of histamine and serotonin from mast cells cause sneezing, watery eyes, difficulty in breathing. [1] Treatment: antihistamines, adrenaline and steroids. [½] Autoimmunity: the memory-based immune system can distinguish self from non-self; sometimes it attacks self-cells, e.g. rheumatoid arthritis. [1½]
OR
Primary: bone marrow (all blood cells including lymphocytes are produced; B-cells mature here) and thymus (T-cells mature). [1] Secondary: spleen (large bean-shaped, filters blood and stores lymphocytes), lymph nodes (trap antigens), tonsils, Peyer’s patches of the small intestine, appendix, and MALT (mucosa-associated lymphoid tissue, about 50 % of the lymphoid tissue). [2]
18. Ans.
AIDS (Acquired Immuno Deficiency Syndrome) is a deficiency of the immune system caused by the HIV (a retrovirus). [½] Transmission: sexual contact, contaminated blood and blood products, shared needles, and from infected mother to child; not by touch or casual contact. [1] Prevention: use of disposable needles, safe (screened) blood, free distribution of condoms, avoiding unprotected sex, education and counselling (NACO, WHO programmes). [1½]
OR
After entry into the body, the virus enters macrophages, where the RNA genome is replicated to form viral DNA by reverse transcriptase; the viral DNA gets incorporated into the host DNA and directs the infected cells to produce virus particles. [1½] The macrophages continue to produce viruses and act as an HIV factory. The virus also enters helper T-lymphocytes, replicates and produces progeny that attack other helper T-cells. [1] The number of TH cells decreases, immunity is lost, and the patient suffers from fever, diarrhoea and weight loss and from infections (TB, fungi, Toxoplasma) – AIDS. [½]
19. Ans.
Cancer is uncontrolled cell division due to loss of contact inhibition; the cells form a tumour (benign or malignant – metastasis). [½] Causes: carcinogens (physical, chemical, biological), oncogenic viruses, tobacco smoke. [½] Detection: biopsy and histopathological study, blood and bone-marrow tests (leukaemia), radiography, CT scan, MRI, antibodies against cancer-specific antigens, molecular techniques. [1] Treatment: surgery, radiation therapy, chemotherapy, and immunotherapy with biological response modifiers such as α-interferon. [1]
OR
Physical carcinogens: ionising radiations such as X-rays, γ-rays and non-ionising UV rays. Chemical carcinogens: tobacco smoke (lung cancer) and other chemicals. Biological: oncogenic viruses with viral oncogenes. [1½] Oncogenes: cellular oncogenes (c-onc) or proto-oncogenes are normal genes which, when activated under certain conditions, lead to oncogenic transformation of the cells. [1½]
20. Ans.
Opioids (heroin/smack): from morphine (latex of Papaver somniferum); bind to opioid receptors in the CNS and gastrointestinal tract; depressant that slows body functions. [1] Cannabinoids: from Cannabis sativa (marijuana, hashish, charas, ganja); bind to cannabinoid receptors in the brain and affect the cardiovascular system. [1] Cocaine: a coca alkaloid from Erythroxylum coca; interferes with the transport of the neurotransmitter dopamine; strong stimulatory action on the CNS, producing euphoria and, in excess, hallucinations. [1]
OR
Tobacco: nicotine stimulates the adrenal gland to release adrenaline and noradrenaline, raising blood pressure and heart rate; smoking causes cancers of the lung, urinary bladder and throat, bronchitis, emphysema, coronary heart disease and gastric ulcer; chewing causes oral cancer. [1½] Alcohol: damages the nervous system and the liver (cirrhosis), harms the foetus, causes reckless behaviour. [1] Doping: use of drugs (e.g. anabolic steroids) by sportspersons to enhance performance. [½]
SECTION – D (Case-Based · 4 Marks each)
21. Ans.
(i) Plasmodium falciparum (malignant malaria); vector: female Anopheles mosquito. [1]
(ii) Haemozoin, released when the parasite-infected RBCs rupture. [1]
(iii) Sporozoites; they multiply first in the liver cells. [1] Control: eliminate stagnant water/breeding sites, use mosquito nets and repellents, introduce larvivorous fish (Gambusia), spray insecticides. [1] [2]
22. Ans.
(i) Passive immunity; IgA antibodies in colostrum. [1]
(ii) Active (acquired) immunity. The vaccine produces memory B- and T-cells, which give a quick and strong secondary response. [1]
(iii) Antivenom contains readymade antibodies (not produced by the person’s own cells), so it is passive. [1] Passive immunity acts quickly but is short-lived with no memory; active immunity is slow but long-lasting with memory. [1] [2]
SECTION – E (Long Answer · 5 Marks each)
23. Ans.
Typhoid: Salmonella typhi; sustained high fever (39–40 °C), weakness, stomach pain, constipation, headache and loss of appetite; intestinal perforation and death in severe cases; transmitted through contaminated food and water; confirmed by the Widal test. [1]
Pneumonia: Streptococcus pneumoniae and Haemophilus influenzae infect the alveoli, which fill with fluid; fever, chills, cough, headache; lips and nails may turn bluish; spread by droplets/aerosols and sharing of glasses and utensils. [1]
Common cold: rhinoviruses; infect the nose and respiratory passage (not the lungs); nasal congestion and discharge, sore throat, hoarseness, cough, headache, tiredness; lasts 3–7 days; droplets and contaminated objects. [1]
Malaria: Plasmodium (P. vivax, P. malariae, P. falciparum – the most serious); bite of a female Anopheles; sporozoites → liver → RBCs → haemozoin release causing recurring chill and high fever every 3–4 days. [2]
Pneumonia: Streptococcus pneumoniae and Haemophilus influenzae infect the alveoli, which fill with fluid; fever, chills, cough, headache; lips and nails may turn bluish; spread by droplets/aerosols and sharing of glasses and utensils. [1]
Common cold: rhinoviruses; infect the nose and respiratory passage (not the lungs); nasal congestion and discharge, sore throat, hoarseness, cough, headache, tiredness; lasts 3–7 days; droplets and contaminated objects. [1]
Malaria: Plasmodium (P. vivax, P. malariae, P. falciparum – the most serious); bite of a female Anopheles; sporozoites → liver → RBCs → haemozoin release causing recurring chill and high fever every 3–4 days. [2]
OR
Amoebiasis: Entamoeba histolytica, large intestine; constipation, abdominal pain, cramps, stool with mucus and blood clots; contaminated food/water; houseflies as carriers. [1]
Ascariasis: Ascaris; internal bleeding, muscular pain, fever, anaemia, blockage of the intestine; eggs in the faeces of infected persons contaminate soil, water. [1]
Filariasis: Wuchereria; lymphatic vessels, elephantiasis; female Culex. [1]
Ringworm: fungi Microsporum, Trichophyton, Epidermophyton; dry scaly lesions with intense itching; soil, towels, clothes, combs. [1]
Dengue and chikungunya: viral diseases spread by Aedes mosquitoes. Prevention: personal and public hygiene, safe water and food, proper waste disposal, vector control (no stagnant water, Gambusia, nets, insecticides), vaccination. [1]
Ascariasis: Ascaris; internal bleeding, muscular pain, fever, anaemia, blockage of the intestine; eggs in the faeces of infected persons contaminate soil, water. [1]
Filariasis: Wuchereria; lymphatic vessels, elephantiasis; female Culex. [1]
Ringworm: fungi Microsporum, Trichophyton, Epidermophyton; dry scaly lesions with intense itching; soil, towels, clothes, combs. [1]
Dengue and chikungunya: viral diseases spread by Aedes mosquitoes. Prevention: personal and public hygiene, safe water and food, proper waste disposal, vector control (no stagnant water, Gambusia, nets, insecticides), vaccination. [1]
24. Ans.
Innate immunity (non-specific, present at birth): physical (skin, mucus), physiological (gastric acid, saliva, tears), cellular (neutrophils, monocytes, NK cells, macrophages) and cytokine (interferons) barriers. [1½]
Acquired immunity: pathogen-specific, with memory; the primary response is low, the secondary (anamnestic) response is quick and intense. [1]
Humoral (antibody-mediated) immunity: B-lymphocytes produce antibodies (H2L2: IgA, IgM, IgE, IgG) in the blood. [1]
Cell-mediated immunity (CMI): T-lymphocytes; they help B-cells to produce antibodies and are responsible for graft rejection, so organ transplant needs matching and immunosuppressants. [1]
Active immunity – own antibodies (infection/vaccine); passive – readymade antibodies (colostrum, antivenom). [½]
Acquired immunity: pathogen-specific, with memory; the primary response is low, the secondary (anamnestic) response is quick and intense. [1]
Humoral (antibody-mediated) immunity: B-lymphocytes produce antibodies (H2L2: IgA, IgM, IgE, IgG) in the blood. [1]
Cell-mediated immunity (CMI): T-lymphocytes; they help B-cells to produce antibodies and are responsible for graft rejection, so organ transplant needs matching and immunosuppressants. [1]
Active immunity – own antibodies (infection/vaccine); passive – readymade antibodies (colostrum, antivenom). [½]
OR
AIDS: caused by HIV (retrovirus, RNA genome). The virus enters macrophages, reverse transcriptase makes viral DNA which integrates into host DNA; it then enters helper T-cells and replicates, so TH cells decline and immunity fails. [1½] Transmission: sexual contact, contaminated blood, shared needles, mother to child. Diagnosis: ELISA. Prevention: safe blood, disposable needles, condoms, education (NACO). [1]
Cancer: uncontrolled cell division (loss of contact inhibition); benign tumours stay at the site of origin, malignant tumours show metastasis. [1] Causes: physical (X-rays, γ-rays, UV), chemical (tobacco smoke) and biological (oncogenic viruses; proto-oncogenes). Treatment: surgery, radiation, chemotherapy, immunotherapy with α-interferon. [1½]
Cancer: uncontrolled cell division (loss of contact inhibition); benign tumours stay at the site of origin, malignant tumours show metastasis. [1] Causes: physical (X-rays, γ-rays, UV), chemical (tobacco smoke) and biological (oncogenic viruses; proto-oncogenes). Treatment: surgery, radiation, chemotherapy, immunotherapy with α-interferon. [1½]
25. Ans.
Adolescence (12–18 years) is a bridge between childhood and adulthood, a period of curiosity and experimentation – so risk of drug and alcohol abuse. [½]
Drugs: opioids (heroin – depressant), cannabinoids (marijuana, hashish), cocaine (stimulant, dopamine), hallucinogens (Atropa belladonna, Datura), tobacco (nicotine), alcohol. [1]
Addiction and dependence: psychological attachment, craving, tolerance; withdrawal syndrome when the dose is stopped. [1]
Effects: reckless behaviour and vandalism, damage to the nervous system, liver (cirrhosis), heart; infections like AIDS and hepatitis-B through shared needles; harm to the family and society; anabolic steroid misuse (doping). [1]
Prevention: avoid undue peer pressure; education and counselling; seeking help from parents and peers; looking for danger signs; professional help from psychologists, psychiatrists and de-addiction programmes. [1½]
Drugs: opioids (heroin – depressant), cannabinoids (marijuana, hashish), cocaine (stimulant, dopamine), hallucinogens (Atropa belladonna, Datura), tobacco (nicotine), alcohol. [1]
Addiction and dependence: psychological attachment, craving, tolerance; withdrawal syndrome when the dose is stopped. [1]
Effects: reckless behaviour and vandalism, damage to the nervous system, liver (cirrhosis), heart; infections like AIDS and hepatitis-B through shared needles; harm to the family and society; anabolic steroid misuse (doping). [1]
Prevention: avoid undue peer pressure; education and counselling; seeking help from parents and peers; looking for danger signs; professional help from psychologists, psychiatrists and de-addiction programmes. [1½]
OR
Primary lymphoid organs: bone marrow and thymus – lymphocytes differentiate into antigen-sensitive cells (B-cells in bone marrow; T-cells in thymus). [1] Secondary lymphoid organs: spleen, lymph nodes, tonsils, Peyer’s patches, appendix and MALT – the sites where lymphocytes interact with antigens and proliferate. [1]
Allergy: exaggerated response to allergens (IgE, histamine release from mast cells); treated by antihistamines, adrenaline and steroids. [1]
Autoimmunity: the immune system attacks self-cells, e.g. rheumatoid arthritis. [1]
Transplantation: graft rejection occurs as the body recognises non-self tissue; tissue matching and immunosuppressant drugs are used. [1]
Allergy: exaggerated response to allergens (IgE, histamine release from mast cells); treated by antihistamines, adrenaline and steroids. [1]
Autoimmunity: the immune system attacks self-cells, e.g. rheumatoid arthritis. [1]
Transplantation: graft rejection occurs as the body recognises non-self tissue; tissue matching and immunosuppressant drugs are used. [1]
QUICK REVISION · HIGH-YIELD POINTS (NEET / CBSE)
- Typhoid – Salmonella typhi (Widal test). Pneumonia – Streptococcus pneumoniae + Haemophilus influenzae (alveoli). Common cold – rhinoviruses (not lungs). Ringworm – fungi (Microsporum, Trichophyton, Epidermophyton).
- Malaria: Plasmodium (P. falciparum – most serious); female Anopheles = vector; sporozoites → liver → RBC; haemozoin → chill and fever every 3–4 days; gametocytes → mosquito gut → sporozoites in salivary gland.
- Amoebiasis – Entamoeba histolytica (large intestine, housefly); Ascariasis – Ascaris (roundworm); Filariasis – Wuchereria (Culex, lymphatic vessels); Dengue and chikungunya – Aedes.
- Innate immunity barriers: physical, physiological, cellular, cytokine (interferons). Acquired: specific, memory; primary response low, secondary quick and intense.
- B-cells → antibodies (H2L2; IgA, IgM, IgE, IgG) – humoral; T-cells → CMI. Active immunity: slow, memory; passive: quick, no memory (colostrum IgA, IgG via placenta, antivenom).
- Lymphoid organs: primary – bone marrow, thymus; secondary – spleen, lymph nodes, tonsils, Peyer’s patches, appendix, MALT. Allergy: IgE, histamine; autoimmunity: rheumatoid arthritis.
- AIDS: HIV (retrovirus, RNA) → macrophages → reverse transcriptase → helper T-cells decline; ELISA; spread by sexual contact, blood, needles, mother to child; not by touch.
- Cancer: loss of contact inhibition; benign (no metastasis) vs malignant (metastasis); carcinogens physical, chemical, biological; proto-oncogenes; biopsy, CT, MRI; treatment: surgery, radiation, chemotherapy, α-interferon.
- Drugs: heroin (diacetylmorphine from morphine, Papaver somniferum), cannabinoids (Cannabis sativa), cocaine (Erythroxylum coca; dopamine), nicotine (tobacco), alcohol (liver cirrhosis).
- Adolescence 12–18 years; addiction, tolerance, withdrawal syndrome; prevention – counselling, avoiding peer pressure, medical help; doping with anabolic steroids.
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