Human Health and DiseaseNEET Zoology · Class 12 · NCERT Chapter 4

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Adrenaline, also known as epinephrine, is produced under stress conditions and stimulates glycogenolysis in the liver, increasing blood glucose levels. NCERT XII chapter Human Health and Disease describes adrenaline's role in the fight-or-flight response, so option (c) is correct.

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Rennin, a proteolytic enzyme present in gastric juice, curdles milk by converting casein to paracasein, which is the initial step in milk digestion. NCERT XII chapter Human Health and Disease describes this process, so option (c) is correct.

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Fructose is absorbed into the blood through the mucosa cells of the intestine by facilitated transport, which involves specific carrier proteins. NCERT XII chapter Human Health and Disease describes this process for fructose absorption, so option (b) is correct.

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A person with blood group AB has both A and B antigens on the RBCs but lacks both anti-A and anti-B antibodies in the plasma. This makes AB the universal recipient, as they can receive blood from any ABO blood group, so option (a) is correct.

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Retinal is a derivative of Vitamin A, not Vitamin C. NCERT XII chapter Human Health and Disease states that retinal is a light-absorbing chromophore derived from Vitamin A, making option (c) incorrect.

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Symptoms of AIDS typically appear when HIV has damaged a large number of helper T-lymphocytes, leading to a compromised immune system. NCERT XII chapter Human Health and Disease explains that the progression to AIDS is marked by a significant decline in CD4+ T-cell count, so option (c) is correct.

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Cell mediated immunity (CMI) is responsible for graft rejection.

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Babesiosis is a disease caused by a protozoan, Babesia bigemina. The vector is tick, so disease is also called tick fever in cattle.

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Antibodies are present in serum. They are glycoproteins and also called gammaglobulins synthesized in lymph nodes.

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IgA is present in external body secretion including colostrum and milk. They provide naturally acquired passive immunity to child.

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Emphysema is a chronic respiratory disorder caused due chronic cigarette smoking in which the alveolar walls are damaged due to which the respiratory surface is decreased.

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Rhodopsin which is a photosensitive pigment present in the human eye is made of opsin and retinal.

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Asthma is an allergic reaction characterized by spasm of bronchi muscles because of effect of histamine released by mast cells.

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If self and non – self recognition power is lost then immune cells can attack our own body cells and cause an auto immune disease.

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OPV is of 2 types: (i) OPV sabin – Live attenuated vaccine www.vedantu.com 61 (ii) OPV salk – Killed vaccine

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Gastric acid i.e. HCl is secreted by parietal or oxyntic cells.

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The opening of hepatopancreatic duct into the duodenum is guarded by sphincter of Oddi

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In hepatic portal system, hepatic portal vein carries maximum amount of nutrients from intestine to liver.

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Gonorrhoea – Neisseria (Bacteria) Syphilis – Treponema (Bacteria) Genital Warts – Human papilloma virus (Virus) AIDS – HIV (Virus)

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Non-acceptance or rejection of graft or transplanted tissues/organs is due to cell mediated immune response.

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Epiphyseal plate is responsible for the growth of bone which close after adolescence so hypersecretion of growth hormone in adults does not cause further increase in height.

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Thalassemia differs from sickle-cell anaemia in that the former is a quantitative problem of synthesising too few globin molecules while the latter is a qualitative problem of synthesising an incorrectly functioning globin.

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Parietal cells secrete hydrochloric acid and intrinsic factor, the latter of which is essential for the absorption of vitamin B12, a critical component for erythropoiesis. NCERT XII chapter Human Health and Disease highlights the role of intrinsic factor in vitamin B12 absorption, so option (d) is correct.

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Silicosis is an occupational respiratory disorder caused by the inhalation of silica dust, leading to lung inflammation and scarring. NCERT XII chapter Human Health and Disease lists silicosis as a common occupational disease among miners and stone cutters, so option (b) is correct.

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Elephantiasis, caused by the mosquito-transmitted filarial worm $\text{Wuchereria}$ bancrofti, leads to chronic inflammation of lymphatic vessels. NCERT XII chapter Human Health and Disease describes this condition as a result of lymphatic system obstruction, so option (c) is correct.

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Alzheimer’s disease is not an autoimmune disease; it is a neurodegenerative disorder. Rheumatoid arthritis, psoriasis, and vitiligo are all examples of autoimmune diseases, where the immune system attacks the body's own tissues. NCERT XII chapter Human Health and Disease classifies these conditions accordingly, so option (a) is correct.

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The conversion of milk to curd by lactic acid bacteria increases the amount of Vitamin B${}_{12}$. This is because these bacteria synthesize Vitamin B${}_{12}$ during fermentation, enhancing the nutritional value of the curd. Option (a) is correct.

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Factual NCERT ❑❑❑ 26 CODE: R3 – Answer Key: 1. (3) 2. (1) 3. (1) 4. (2) 5. (4) 6. (1) 7. (1) 8. (3) 9. (4) 10 (3) 11. (4) 12. (4) 13. (4) 14. (4) 15. (3) 16. (3) 17. (4) 18. (2) 19. (1) 20. (3) 21. (2) 22. (1) 23. (2) 24. (2) 25. (3) 26. (4) 27. (4) 28. (4) 29. (3) 30. (4) 31. (3) 32. (1) 33. (3) 34. (2) 35. (3) 36. (4) 37. (1) 38. (1) 39. (4) 40. (1) 41. (3) 42. (4) 43. (3) 44. (4) 45. (2) 46. (2) 47. (1) 48. (2) 49. (2) 50. (4) 51. (3) 52. (4) 53. (4) 54. (4) 55. (4) 56. (4) 57. (3) 58. (3) 59. (4) 60. (4) 61. (2) 62. (2) 63. (2) 64. (1) 65. (2) 66. (2) 67. (2) 68. (3) 69. (1) 70. (3) 71. (3) 72. (1) 73. (3) 74. (2) 75. (2,3) 76. (3) 77. (3) 78. (3) 79. (1) 80. (1) 81. (1) 82. (1) 83. (4) 84. (2) 85. (3) 86. (4) 87. (4) 88. (2) 89. (4) 90. (4) 91. (3) 92. (4) 93. (3) 94. (2) 95. (1) 96. (2) 97. (1) 98. (2) 99. (3) 100. (2) 101. (3) 102. (3) 103. (2) 104. (2) 105. (1) 106. (2) 107. (1) 108. (2) 109. (4) 110. (3) 111. (3) 112. (3) 113. (3) 114. (1) 115. (1) 116. (3) 117. (3) 118. (1) 119. (4) 120. (3) 121. (1) 122. (3) 123. (4) 124. (1) 125. (3) 126. (2) 127. (3) 128. (2) 129. (1) 130. (4) 131. (4) 132. (4) 133. (1) 134. (3) 135. (1) 136. (3) 137. (4) 138. (2) 139. (3) 140. (1) 141. (1) 142. (1) 143. (2) 144. (4) 145. (3) 146. (4) 147. (3) 148. (4) 149. (3) 150. (1) 151. (4) 152. (4) 153. (4) 154. (3) 155. (4) 156. (3) 157. (4) 158. (1) 159. (1) 160. (4) 161. (1) 162. (4) 163. (4) 164. (2) 165. (1) 166. (2) 167. (3) 168. (4) 169. (3) 170. (4) 171. (3) 172. (3) 173. (1) 174. (1) 175. (4) 176. (2) 177. (4) 178. (1) 179. (1) 180. (1) 27

Solution

Ref. XII NCERT Chapter- 10, Page No. 187

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Ref. XI NCERT Chapter- 06, Page No. 96

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Ref. XII NCERT Chapter- 14, Page No. 249 23 SPACE FOR ROUGH WORK

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Ref. XI NCERT Chapter- 03, Page No. 38

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Factual NCERT

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Nitrogenous waste removed by dialysis. 163 Which of the following pairs of organelles does not contain DNA? (1) Nuclear envelope and Mitochondria (2) Mitochondria and Lysosomes (3) Chloroplast and Vacuoles (4) Lysosomes and Vacuoles Solution: (4) Factual NCERT

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Ref. XII NCERT Chapter- 10, Page No. 187

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Ref. XII NCERT Chapter- 16, Page No. 279

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- Eosinophils release granules containing histamine and are involved in allergic reactions and parasitic infections.
- Basophils release histaminase and other destructive enzymes.
- Neutrophils perform phagocytosis to engulf and destroy pathogens.
- Lymphocytes are involved in the immune response, including producing antibodies and cell-mediated immunity.

Solution

- Typhoid is caused by $\text{Salmonella}$ typhi (bacterium).
- Pneumonia is caused by $\text{Haemophilus}$ influenzae (bacterium).
- Filariasis is caused by $\text{Wuchereria}$ bancrofti (filarial worm).
- Malaria is caused by $\text{Plasmodium}$ species (protozoan).

Thus, the correct matching is (b) (iii) (iv) (i) (ii).

Solution

Gonorrhoea, Syphilis, and Genital herpes are all sexually transmitted diseases (STDs). Malaria, Filaria, and Cancer are not STDs. NCERT XII chapter Human Health and Disease lists these as common STDs, so option (a) is correct.

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Goblet cells are modified columnar epithelial cells that secrete mucus to lubricate and protect the lining of the alimentary canal. NCERT XII chapter Human Health and Disease describes goblet cells as part of the mucous membrane, so option (b) is correct.

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The ileum is a highly coiled part of the small intestine, responsible for the absorption of nutrients. NCERT XI chapter Human Health and Disease describes the ileum as the final section of the small intestine, so option (c) is correct.

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Snow-blindness in the Antarctic region is caused by inflammation of the cornea due to high doses of UV-B radiation, which can be reflected off snow surfaces. NCERT XII chapter Human Health and Disease explains that UV-B radiation can cause photokeratitis, commonly known as snow-blindness, so option (b) is correct.

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The infectious stage of $\text{Plasmodium}$ that enters the human body is the sporozoite stage. Sporozoites are transmitted through the saliva of an infected female Anopheles mosquito, so option (b) is correct.

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Glycosuria and ketonuria are indicative of Diabetes Mellitus. Glycosuria results from high blood glucose levels, while ketonuria occurs due to increased ketone body production when the body uses fat for energy instead of glucose. Option (c) is correct.

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- $\text{Clostridium butylicum}$ produces butyric acid.
- $\text{Trichoderma polysporum}$ produces cyclosporin-A.
- $\text{Monascus purpureus}$ produces a blood cholesterol-lowering agent.
- $\text{Aspergillus niger}$ produces citric acid.

Thus, the correct option is (b).

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The QRS complex in a standard ECG represents the depolarisation of the ventricles, which initiates ventricular contraction. NCERT XII chapter Human Health and Disease describes the QRS complex as the electrical activity associated with ventricular depolarisation, so option (c) is correct.

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Collagen is the most abundant protein in animals, forming the structural framework of bones, skin, and connective tissues. NCERT XII chapter Human Health and Disease highlights collagen's prevalence and structural role, so option (b) is correct.

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Enterokinase converts trypsinogen into trypsin, an active protease in the small intestine. NCERT XII chapter Human Health and Disease describes this activation process, so option (b) is correct.

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Active immunity involves the production of antibodies by the host's immune system, which takes time to develop a full response, not immediately. Therefore, option (c) is incorrect. NCERT XII chapter Human Health and Disease explains that active immunity is long-lasting but not immediate.

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Aldosterone promotes the reabsorption of ${\text{Na}}^{+}$ and water from the renal tubules, reducing urine volume and preventing diuresis. NCERT XII chapter Human Health and Disease explains that aldosterone helps in water retention, so option (b) is correct.

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Vitamin B${}_{12}$ deficiency leads to pernicious anemia, characterized by RBC deficiency. NCERT XII chapter Human Health and Disease explains that Vitamin B${}_{12}$ is essential for DNA synthesis and RBC production, so option (a) is correct.

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Myasthenia gravis is a chronic autoimmune disorder that affects the neuromuscular junction, causing fatigue, weakening, and paralysis of skeletal muscles. NCERT XII chapter Human Health and Disease describes this condition, so option (c) is correct.

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Favourable conditions for the formation of oxyhaemoglobin at the alveoli include high partial pressure of oxygen (${\text{pO}}_2$), low partial pressure of carbon dioxide (${\text{pCO}}_2$), fewer hydrogen ions (${\text{H}}^{+}$), and lower temperature. These conditions promote the binding of oxygen to haemoglobin, as described in NCERT XII Human Health and Disease, so option (a) is correct.

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The sphincter of Oddi is located at the junction of the hepato-pancreatic duct and the duodenum, controlling the flow of bile and pancreatic juice into the duodenum. NCERT XII chapter Human Health and Disease describes this anatomical feature, so option (b) is correct.

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The partial pressures of gases in the alveoli are $p{\text{O}}_2=95\text{mm Hg}$ and $p{\text{CO}}_2=40\text{mm Hg}$. These values facilitate the diffusion of oxygen into the blood and carbon dioxide out of the blood, as described in NCERT XII Human Health and Disease, so option (c) is correct.

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Succus entericus is the term used for intestinal juice, which is secreted by the intestinal glands to aid in digestion. NCERT XII chapter Human Health and Disease defines succus entericus as the collective secretion of the intestinal glands, so option (b) is correct.

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Veneral diseases, or sexually transmitted infections, can spread through transfusion of blood from an infected person and from an infected mother to the foetus. Kissing and using sterile needles do not typically transmit these infections, so option (c) is correct.

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Persons with the AB blood group are called universal recipients because their plasma lacks antibodies anti-A and anti-B. This absence allows them to receive blood from any ABO blood group without causing an immune reaction, so option (d) is correct.

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Thrombin is the enzyme that converts fibrinogen to fibrin during blood clotting. This process is part of the coagulation cascade described in NCERT XII Human Health and Disease, so option (a) is correct.

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Both the assertion and the reason are true, but the reason does not fully explain the assertion. Altitude sickness involves more than just low atmospheric pressure; it includes reduced partial pressure of oxygen, leading to hypoxia and the mentioned symptoms. NCERT XII chapter Human Health and Disease covers the physiological responses to high altitude, so option (b) is correct.

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Adenosine deaminase deficiency leads to severe combined immunodeficiency (SCID), a dysfunction of the immune system. NCERT XII chapter Human Health and Disease explains that this enzyme is crucial for the proper functioning of the immune system, so option (a) is correct.

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- Filariasis is caused by $\text{Wuchereria bancrofti}$ (iii).
- Amoebiasis is caused by $\text{Entamoeba histolytica}$ (iv).
- Pneumonia is caused by $\text{Haemophilus influenzae}$ (i).
- Ringworm is caused by $\text{Trichophyton}$ (ii).

Solution

Option ( 3) is the correct answer as autoimmune disorder is a condition where body defense mechanism recognises its own cells as foreign bodies. Sometimes, due to geneti c and other unknown reasons, the body attacks self- cells. Rheumatoid arthritis is an example where body attacks self cells (synovial membrane). So Statement I is correct but Statement II is incorrect.

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Option (1) is the correct answer because Arthritis is inflammation of joints. Option ( 3) is incorrect because myasthenia gravis is an immune disorder affecting neuro- muscular junction leading to fatigue, weakening and paralysis of skeletal muscle. Option ( 4) is incorrect because muscular dystrophy is progressive degeneration of skeletal muscle mostly due to genetic disorder. Option (2) is incorrect because tetany is rapid spasms in muscle due to low Ca++ in body fluid.

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Option (4) is the correct answer as genetically engineered ymphocyctesl are not immortal cells and die after some time. Option ( 3) is not the correct answer as the lymphocytes from patient ’s blood are grown in culture, outside the body but it is not the correct reason. In option (2), if the gene isolated from bone marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.

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Option (4) is the correct answer as acquired immunity is a specific type of defence which is not present at the time of birth. Option (3), (1) and (2) are true statements and hence cannot be the answer. Anamnestic response or secondary immune response is a highly intensified response due to memory of first encounter. When our body encounters a pathogen for the first time then the body elicit s the primary immune response. When there is a subsequent encounter with the same pathogen, secondary or anamnestic immune response is elicited.

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Algal blooms caused by excess organic matter in water do not improve water quality or promote fisheries. Instead, they deplete oxygen levels, leading to the death of aquatic organisms. NCERT XII chapter Human Health and Disease explains that algal blooms are harmful to aquatic ecosystems, so option (c) is incorrect.

Solution

- Oxidative decarboxylation is catalyzed by $\text{Pyruvate dehydrogenase}$.
- Glycolysis is the $\text{EMP pathway}$.
- Oxidative phosphorylation involves the $\text{Electron transport system}$.
- The Tricarboxylic acid cycle includes the action of $\text{Citrate synthase}$.

Solution

Melonate inhibits the growth of pathogenic bacteria by inhibiting the activity of succinic dehydrogenase, an enzyme in the citric acid cycle. NCERT XII chapter Human Health and Disease discusses this mechanism of action for melonate, so option (b) is correct.

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- A. Ringworm is caused by $\text{Trichophyton}$ (fungus).
- B. Filariasis is caused by $\text{Wuchereria bancrofti}$ (filarial worm).
- C. Malaria is caused by $\text{Plasmodium vivax}$ (protozoan).
- D. Pneumonia is caused by $\text{Haemophilus influenzae}$ (bacterium).

Solution

- Iron (Fe) is an activator of catalase, an enzyme that decomposes hydrogen peroxide.
- Zinc (Zn) is essential for the synthesis of auxin, a plant hormone.
- Boron (B) is involved in cell elongation and differentiation.
- Molybdenum (Mo) is a component of nitrate reductase, an enzyme involved in nitrogen metabolism.

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Biomagnification refers to the increase in concentration of toxicants at successive trophic levels. This is a key concept in NCERT XII Human Health and Disease, making option (c) correct.

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In human pedigree analysis, the symbol for mating between relatives is represented by a horizontal line connecting two individuals, with a vertical line descending from the midpoint to a child, as shown in option (c). This indicates a consanguineous marriage, so option (c) is correct.

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Gonorrhoea, caused by the bacterium $\text{Neisseria gonorrhoeae}$, is completely curable with appropriate antibiotic treatment when detected early. NCERT XII chapter Human Health and Disease states that bacterial infections like gonorrhoea can be effectively treated with antibiotics, so option (c) is correct.

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- Heroin slows down body functions by acting as a depressant on the central nervous system.
- Marijuana can affect the cardiovascular system, increasing heart rate and blood pressure.
- Cocaine interferes with the transport of dopamine, leading to increased levels in the brain.
- Morphine acts as a powerful painkiller by binding to opioid receptors.

Solution

Statement I is true as low temperatures preserve enzymes by slowing down molecular motion, while high temperatures denature proteins, disrupting enzyme structure and function. Statement II is also true, as competitive inhibitors mimic the substrate and compete for the active site of the enzyme, as described in NCERT XI chapter Biomolecules. Therefore, option (b) is correct.

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Serum and urine analysis are used for monitoring disease progression and general health, not for early diagnosis. Techniques like ELISA, PCR, and recombinant DNA technology are specifically used for early detection of pathogens or disease markers, so option (c) is correct.

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- Gene ‘a’ codes for transacetylase, which modifies the inducer.
- Gene ‘y’ codes for $\beta$-galactosidase, which breaks down lactose.
- Gene ‘i’ codes for the repressor protein, which inhibits transcription.
- Gene ‘z’ codes for permease, which transports lactose into the cell.

Solution

Statement I is correct as electrostatic precipitators are widely used in thermal power plants to remove particulate matter from exhaust gases. Statement II is incorrect because electrostatic precipitators do not remove ionising radiations; they primarily remove particulate matter. Therefore, option (d) is correct.

Solution

The correct answer is option (2) as Typhoid – Caused by Salmonella typhimurium (Bacteria) Leishmaniasis – Caused by protozoan i.e., Leishmania donovani Ringworm – Caused by fungi belonging to the genera Microsporum, Trichophyton and Epidermophyton Filariasis – Caused by Wuchereria bancrofti and Wuchereria malayi (Nematode)

Solution

The correct answer is option (2) as Myasthenia gravis, Rheumatoid arthritis and Systemic Lupus Erythematosus (SLE) are autoimmune disorders. Muscular dystrophy is a genetic disorder which progressively affects the skeletal muscles. Gout is the inflammation of joints due to deposition of uric acid crystals. Option (1), (3) and (4) are not the correct answer because all of them are not autoimmune disorders.

Solution

The correct option is (4) as A. Cocaine – Obtained from plant Erythroxylum coca, stimulating action on CNS. B. Heroin – Formed by the acetylation of morphine which is obtained from plant Papaver somniferum. C. Morphine – Obtained from Papaver somniferum, is an effective sedative in surgery. D. Marijuana – Obtained from Cannabis sativa , produces hallucinogenic effect and affects cardiovascular system of the body. SECTION-B

Solution

The correct answer is option no. (1) as both statements I and II are correct. In humans, the bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced. Both bone-marrow and thymus provide micro -environments for the development and maturation of T - lymphocytes. Options (2), (3) and (4) are incorrect.

Solution

- Computed tomography and magnetic resonance imaging (A) are used to detect cancers of internal organs.
- Chemotherapeutic drugs (B) target cancerous cells, not non-cancerous cells.
- α-interferon (C) activates the immune system and helps in destroying tumours.
- Chemotherapeutic drugs (D) are biological response modifiers.
- In leukaemia, blood cell counts (E) are often increased, not decreased.

Options (B) and (E) are incorrect, so the correct answer is (b) A, C, D.

Solution

The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes. After maturation, the lymphocytes migrate into secondary lymphoid organs like spleen, lymph nodes, Peyer’s patches of small intestine and appendix. These secondary lymphoid organ provide the sites for interaction of lymphocytes with the antigen.

Solution

Neoplastic characteristics of cells include uncontrolled proliferation (A), rapid growth (B), and the ability to invade and damage surrounding tissues (C). These features define cancerous cells, as described in NCERT XII Human Health and Disease, so option (b) is correct.

Solution

The antigen binding site is located at the N-terminal region of the antibody molecules, not the C-terminal region. The C-terminal region contains the constant domains of the heavy and light chains, so option (c) is incorrect.

Solution

The primary lymphoid organs are bone marrow and thymus where immature lymphocytes differentiate into antigen-sensitive lymphocytes.

After maturation, the lymphocytes migrate into secondary lymphoid organs like spleen, lymph nodes, Peyer's patches of small intestine and appendix.

These secondary lymphoid organ provide the sites for interaction of lymphocytes with the antigen.

Solution

Innate immunity is non-specific type of defence, that is present at the time of birth. This is accomplished by providing different types of barriers to the entry of the foreign agents into our body. Acquired immunity is pathogen specific, characterised by memory cells.

Immune response mediated by B-lymphocytes is humoral immunity and other immune response mediated by T-lymphocytes is called cell-mediated immunity.

Solution

Emphysema - Damaged alveolar walls and decreased respiratory surface

Angina pectoris - Acute chest pain when not enough oxygen is reaching to heart muscle

Glomerulonephritis - Inflammation of glomeruli of kidney

Tetany - Rapid spasms in muscle due to low Ca²⁺ in body fluid