Samacheer Kalvi Class 12 Bio Zoology Solutions Chapter 7 Human Health and Diseases

 

Question 1. A 30 year old woman has bleedy diarrhoea for the past 14 hours, which one of the following organisms is likely to cause this illness?
(a) Streptococcus pyogens
(b) Clostridium difficile
(c) Shigella dysenteriae
(d) Salmonella enteritidis
Answer: (c) Shigella dysenteriae
In simple words: When someone has bloody diarrhea for many hours, it often means an infection. Among the choices, Shigella dysenteriae is the most likely germ to cause this specific type of illness.

🎯 Exam Tip: Remember to link specific symptoms, like bloody diarrhea, to their common bacterial causes to identify the pathogen correctly.

 

Question 2. Exo-erythrocytic schizogony of Plasmodium takes place in
(a) RBC
(b) Leucocytes
(c) Stomach
(d) Liver
Answer: (d) Liver
In simple words: The "exo-erythrocytic schizogony" part of the Plasmodium life cycle means the parasite multiplies inside cells, but not red blood cells. This stage happens in the liver of the infected person.

🎯 Exam Tip: Understanding the life cycle stages of Plasmodium and their locations (liver, red blood cells, mosquito gut) is crucial for questions about malaria.

 

Question 3. The sporozoites of Plasmodium vivax are formed from
(a) Gametocytes
(b) Sporoblasts
(c) Oocysts
(d) Spores
Answer: (c) Oocysts
In simple words: In the life cycle of the malaria parasite Plasmodium vivax, sporozoites (the infectious form) develop from oocysts. These oocysts are found inside the mosquito.

🎯 Exam Tip: Trace the Plasmodium life cycle from mosquito to human and back, noting the different forms (sporozoites, merozoites, gametocytes) and where they develop.

 

Question 4. Amphetamines are stimulants of the CNS, whereas barbiturates are
(a) CNS stimulant
(b) both a and b
(c) hallucinogenic
(d) CNS depressants
Answer: (d) CNS depressants
In simple words: Amphetamines make your central nervous system (CNS) more active, like a boost. Barbiturates do the opposite; they slow down your CNS, acting as depressants.

🎯 Exam Tip: Differentiate between different classes of drugs (stimulants, depressants, hallucinogens, opioids) by their primary effect on the central nervous system.

 

Question 5. Choose the correctly match pair.
(a) Amphetamines – Stimulant
(b) LSD-Narcotic
(c) Heroin – Psychotropic
(d) Benzodiazepine – Pain killer
Answer: (a) Amphetamines – Stimulant
In simple words: Amphetamines speed up the body's functions, so they are correctly matched as stimulants. The other options are incorrectly paired with their drug categories.

🎯 Exam Tip: Accurately classify common drugs based on their effects (e.g., stimulants, depressants, opioids, hallucinogens) to avoid mismatches.

 

Question 6. The Athlete's foot disease in human is caused by
(a) Bacteria
(b) Fungi
(c) Virus
(d) Protozoan
Answer: (b) Fungi
In simple words: Athlete's foot is a common skin infection that makes skin itchy and flaky, especially between the toes. It is caused by a type of fungus that thrives in warm, moist places.

🎯 Exam Tip: Remember common diseases and the specific type of pathogen (bacteria, virus, fungi, protozoa) that causes them.

 

Question 7. Cirrhosis of liver is caused by chronic intake of
(a) Opium
(b) Alcohol
(c) Tobacco
(d) Cocaine
Answer: (b) Alcohol
In simple words: Cirrhosis is a serious liver disease where the liver gets scarred and damaged. Drinking too much alcohol for a long time is a main reason this happens.

🎯 Exam Tip: Relate lifestyle choices and prolonged exposure to substances to their associated health conditions, such as alcohol with liver damage.

 

Question 8. The sporozoite of the malarial parasite is present in
(a) saliva of infected female Anopheles mosquito.
(b) RBC of human suffering from malaria.
(c) Spleen of infected humans.
(d) Gut of female Anopheles mosquito
Answer: (a) saliva of infected female Anopheles mosquito
In simple words: When a female Anopheles mosquito gets infected with malaria, the sporozoites (the infectious form of the parasite) travel to its salivary glands. This way, the mosquito can pass the infection to humans through its bite.

🎯 Exam Tip: Focus on the specific locations of infectious stages of parasites in both vectors and hosts.

 

Question 9. Where do the following events in the life cycle of Plasmodium takes place?
(a) Fertilization
(b) Development of gametocytes
(c) Release of sporozoites
(d) Schizogony
Answer:
(a) Fertilization – Gut of mosquito
(b) Development of gametocytes – Human RBC's
(c) Release of sporozoites – From Mosquito to the human blood
(d) Schizogony – Human liver cells
In simple words: Different stages of the malaria parasite's life cycle happen in different places. Fertilization occurs in the mosquito's gut, while gametocytes develop in human red blood cells. Sporozoites are released from the mosquito to infect humans, and schizogony (multiplication) takes place in human liver cells.

🎯 Exam Tip: Learn the sequence of events in the Plasmodium life cycle and precisely where each stage occurs, distinguishing between human and mosquito hosts.

 

Question 10. Paratope is an
(a) Antibody binding site on variable regions
(b) Antibody binding site on heavy regions
(c) Antigen binding site on variable regions
(d) Antigen binding site on heavy regions
Answer: (c) Antigen binding site on variable regions
In simple words: A paratope is the specific part of an antibody that recognizes and attaches to an antigen. This binding site is located in the variable regions of the antibody.

🎯 Exam Tip: Clearly distinguish between antigen (what causes the immune response) and antibody (what fights it), and identify their respective binding sites.

 

Question 11. Match the following Malarial types Duration of erythrocytic cycle

Answer:
(a) a - iii (Vivax malaria - 48 hours)
(b) b - i (Quartan malaria - 72 hours)
(c) c - iv (Mild tertian malaria - 2 days)
(d) d - ii (Malignant malaria - 36-48 days)
In simple words: This question asks to link different types of malaria with how long their blood-stage cycle lasts. Each malaria type has a specific time period for its life cycle within red blood cells. Knowing these cycles helps in understanding the fever patterns of malaria.

🎯 Exam Tip: Memorize the key characteristics and life cycle durations for common malarial types as they are frequently tested.

 

Question 12. Assertion (A): Plasmodium vivax is a digenic parasite Reason (R): The primary host of P. vivax is man.
(a) Both (A) and (R) are true. (R) explains (A)
(b) (A) is true (R) is false
(c) Both (A) and (R) are false
(d) (A) is false (R) is true
Answer: (b) (A) is true (R) is false
In simple words: The first statement is correct because Plasmodium vivax needs two hosts to complete its life cycle. However, the second statement is wrong because the primary host for Plasmodium vivax is actually the mosquito, not humans.

🎯 Exam Tip: When dealing with assertion-reason questions, first check if each statement is independently true, then analyze if the reason correctly explains the assertion.

 

Question 13. Assertion (A): Dermatomycosis is a cutaneous infection. Reason (R): Fungus belongs to the order Trichophyton,
(a) Both (A) and (R) are true. (R) explains (A)
(b) (A) is true (R) is false
(c) Both (A) and (R) are false.
(d) (A) is false (R) is true
Answer: (a) Both (A) and (R) are true. (R) explains (A)
In simple words: The first statement is true because dermatomycosis is a skin infection. The second statement is also true as fungi causing these infections often belong to the Trichophyton group. The reason helps explain why dermatomycosis happens.

🎯 Exam Tip: Remember that "cutaneous" refers to the skin, which is often the target for fungal infections like dermatomycosis, commonly caused by dermatophytes such as Trichophyton.

 

Question 14. Assertion (A): Spleen is a primary lymphoid organ Reason (R): Primary lymphoid organs trap antigen and destroy them.
(a) Both (A) and (R) are true. (R) explains (A)
(b) (A) is true (R) is false
(c) Both (A) and (R) are false.
(d) (A) is false (R) is true
Answer: (c) Both (A) and (R) are false
In simple words: Both statements are incorrect. The spleen is a secondary lymphoid organ, not a primary one. Also, primary lymphoid organs are where immune cells mature, not where antigens are trapped and destroyed.

🎯 Exam Tip: Distinguish between primary lymphoid organs (thymus and bone marrow, where lymphocytes mature) and secondary lymphoid organs (spleen, lymph nodes, tonsils, where mature lymphocytes encounter antigens).

 

Question 15. Assertion (A): Paratope is the antigen-binding site. Reason (R): It is a part of antibody
(a) Both (A) and (R) are true. (R) explains (A)
(b) (A) is true (R) is false
(c) Both (A) and (R) are false.
(d) (A) is false (R) is true
Answer: (b) (A) is true (R) is false
In simple words: The first statement is true; a paratope is indeed the part of an antibody that binds to an antigen. However, the second statement is false because the paratope is part of the antibody, it doesn't describe the full structure of the antibody.

🎯 Exam Tip: Understand the key terms in immunology: an epitope is the part of an antigen that an antibody recognizes, and a paratope is the specific region on the antibody that binds to the epitope.

 

Question 16. Assertion (A): HIV is a DNA virus. Reason (R): HIV belongs to genus Lentivirus
(a) Both (A) and (R) are true. (R) explains (A)
(b) (A) is true (R) is false
(c) Both (A) and (R) are false.
(d) (A) is false (R) is true
Answer: (d) (A) is false (R) is true
In simple words: HIV is actually an RNA virus, not a DNA virus, so the assertion is false. But the reason is true, as HIV does belong to the genus Lentivirus.

🎯 Exam Tip: Remember that HIV is a retrovirus, meaning it uses RNA as its genetic material and converts it to DNA inside host cells, making the "DNA virus" assertion incorrect.

 

Question 17. Secretion of HCl in stomach is an example for
(a) Anatomical barriers
(b) Phagocytic barriers
(c) Physiological barriers
(d) Inflammatory barriers
Answer: (c) Physiological barriers
In simple words: The stomach's acid is a chemical defense that fights germs. This type of defense is called a physiological barrier because it uses normal body processes and chemicals to keep us healthy.

🎯 Exam Tip: Physiological barriers refer to functional defenses like pH, temperature, and chemicals that inhibit pathogen growth, unlike physical (anatomical) barriers or cellular (phagocytic) responses.

 

Question 18. Identify the incorrect statement.
(a) Antibody Mediated Immunity was elicited by T cells.
(b) It is a character of vertebrates only
(c) Immunoglobulins act against pathogens and kill them.
(d) It is also called humoral immunity
Answer: (a) Antibody Mediated Immunity was elicited by T cells.
In simple words: The wrong statement is that T cells cause antibody-mediated immunity. Actually, B cells are responsible for producing antibodies, while T cells are involved in cell-mediated immunity.

🎯 Exam Tip: Clearly differentiate between the roles of B cells (antibody production, humoral immunity) and T cells (cell-mediated immunity, direct killing or regulation) in the immune response.

 

Question 19. Production process of blood cells in bone marrow is called
Answer: Haematopoiesis is the name given to the process where new blood cells are made in the bone marrow. This continuous process produces all types of blood cells, ensuring the body has a constant supply of immune cells and oxygen carriers.
In simple words: The making of blood cells in the bone marrow is called haematopoiesis.

🎯 Exam Tip: Ensure correct spelling of biological terms like "haematopoiesis," as slight errors can change the meaning or be considered incorrect.

 

Question 20. Which of the following is not a feature of passive immunity?
(a) It is transient and less effective
(b) Immunological memory is present
(c) Immunity develops immediately
(d) Antibodies are obtained from outside
Answer: (b) Immunological memory is present
In simple words: Passive immunity means you get ready-made antibodies, so your body doesn't learn to fight the disease itself. This means there is no "memory" for future protection, which is why it is not a feature of passive immunity.

🎯 Exam Tip: Remember that passive immunity provides immediate but temporary protection because the recipient's immune system is not activated and thus does not form memory cells.

 

Question 21. is a primary lymphoid organ of birds.
Answer: The Bursa of Fabricius is the primary lymphoid organ found in birds. This organ is crucial for the development and maturation of B lymphocytes, which are key components of the immune system.
In simple words: The Bursa of Fabricius is a main immune organ in birds.

🎯 Exam Tip: While mammals have bone marrow as their primary site for B cell maturation, birds have a specialized organ called the Bursa of Fabricius for this function.

 

Question 22. Match the following.

Answer:
(a) a - ii (Peyer's patches - Intestine)
(b) b - i (BALT - Trachea)
(c) c - iv (Adenoid - Roof of the mouth)
(d) d - iii (Thymus - Heart)
In simple words: This question matches different lymphoid tissues and organs with their correct locations in the body. For instance, Peyer's patches are found in the intestine, and the thymus is near the heart. Knowing these locations helps understand where immune responses happen.

🎯 Exam Tip: Focus on understanding the anatomical locations of various lymphoid organs and tissues, as this helps connect structure to their immune functions.

 

Question 23. Which is not a granulocyte?
(a) Lymphocytes
(b) Neutrophils
(c) Basophils
(d) Eosinophils
Answer: (a) Lymphocytes
In simple words: Granulocytes are a type of white blood cell that have small granules inside them. Lymphocytes do not have these granules, so they are not granulocytes.

🎯 Exam Tip: Remember that granulocytes (neutrophils, eosinophils, basophils) are characterized by prominent cytoplasmic granules, while agranulocytes (lymphocytes, monocytes) lack these granules.

 

Question 24. The L and H chains of immunoglobulin are joined by...................
(a) Hydrogen bonds
(b) disulphide bonds
(c) phosphodiester bonds
(d) ionic bond
Answer: (b) disulphide bonds
In simple words: The light (L) and heavy (H) chains that make up an antibody are connected by strong disulphide bonds. These bonds help hold the antibody's shape together so it can work correctly.

🎯 Exam Tip: Disulphide bonds are crucial for the structural integrity and function of immunoglobulins, allowing them to maintain their Y-shape and effectively bind to antigens.

 

Question 25. type of Immunoglobulin is involved in allergic reactions.
Answer: The immunoglobulin type involved in allergic reactions is IgE. IgE antibodies bind to mast cells and basophils, triggering the release of histamine and other chemicals that cause allergy symptoms.
In simple words: IgE is the type of antibody that causes allergic reactions.

🎯 Exam Tip: Associate IgE with allergic responses and parasitic infections; it's the antibody primarily responsible for mediating these reactions.

 

Question 26. Identify the wrong statement.
(a) Vaccine provide passive acquired immunity
(b) It is made from attenuated or killed microbes.
(c) Vaccines teach our body how to defend from microbes.
(d) MMR is a fist generation vaccine.
Answer: (a) Vaccine provide passive acquired immunity
In simple words: Vaccines actually give you active immunity because they teach your body to make its own defenses. Passive immunity is when you get antibodies from another source, like a mother to a baby.

🎯 Exam Tip: Understand the difference: vaccines stimulate *active* immunity by exposing the body to antigens, leading to the production of memory cells; passive immunity provides *preformed* antibodies.

 

Question 27. developed first vaccine for small pox.
Answer: Edward Jenner developed the first vaccine for smallpox. His pioneering work involved using cowpox to protect against smallpox, laying the foundation for modern vaccinology.
In simple words: Edward Jenner made the first vaccine for smallpox.

🎯 Exam Tip: Edward Jenner's contribution to medicine is foundational; his discovery of the smallpox vaccine is a historically significant milestone in immunology.

 

Question 28. The enzyme attached to RNA of HIV is
(a) RNA polymerase
(b) reverse transcriptase
(c) primase
(d) endonuclease
Answer: (b) reverse transcriptase
In simple words: HIV uses an enzyme called reverse transcriptase to change its RNA into DNA. This is a very important step for the virus to infect human cells.

🎯 Exam Tip: The enzyme reverse transcriptase is a hallmark of retroviruses like HIV, enabling them to convert their RNA genome into DNA, which is then integrated into the host's genome.

 

Question 29. Infection of Ascariasis occur due to
(a) Sand fly
(b) contaminated food
(c) mosquito bite
(d) stagnant water
Answer: (b) contaminated food
In simple words: Ascariasis is caused by roundworms and people get infected when they eat food or drink water that has been contaminated with the worm's eggs.

🎯 Exam Tip: Remember that many parasitic infections like ascariasis are transmitted through the fecal-oral route, highlighting the importance of hygiene and safe food preparation.

 

Question 30. Which of the following statement(s) is true regarding cancer cells?
(a) Neoplasm or tumor cells show uncontrolled growth
(b) They are metastatic
(c) They lack contact inhibition
(d) They may be benign or malignant.
(a) (a) only
(b) (b) and (c)
(c) (d) only
(d) All the options
Answer: (d) All the options
In simple words: All the statements about cancer cells are true. They grow without stopping, can spread to other parts of the body (metastatic), do not stop growing when they touch other cells (lack contact inhibition), and can be either mild (benign) or harmful (malignant).

🎯 Exam Tip: Understanding the key characteristics of cancer cells, such as uncontrolled proliferation, metastasis, and loss of contact inhibition, is fundamental to comprehending cancer biology.

 

Question 31. Study dealing with body's defence mechanism against disease is called
(a) Pathology
(b) Immunology
(c) Microbiology
(d) Dermatology
Answer: (b) Immunology
In simple words: The study of how our body protects itself from sickness and germs is called immunology. It looks at how our immune system works.

🎯 Exam Tip: Immunology is a vast field; remember it as the study of the immune system and how it defends the body from foreign invaders and diseases.

 

Question 32. AIDS is characterized by sharp reduction in number of
(a) helper T cells
(b) killer T cells
(c) superior T cells
(d) B-cells
Answer: (a) helper T cells
In simple words: AIDS is a disease where the number of helper T cells in the body greatly decreases. These cells are very important for a strong immune system.

🎯 Exam Tip: Helper T cells (CD4+ T cells) are critical coordinators of the immune response, and their depletion is a defining characteristic and major cause of immunodeficiency in AIDS.

 

Question 33. Plague and malaria are caused by and respectively.
(a) bacteria and virus
(b) fungi and protozoa
(c) bacteria and protozoan
(d) fungi and bacteria
Answer: (c) bacteria and protozoan
In simple words: Plague is caused by bacteria, and malaria is caused by a protozoan parasite. This question links the disease to the correct type of germ that causes it.

🎯 Exam Tip: For disease-causing agents, distinguish between bacteria (like Yersinia pestis for plague) and protozoans (like Plasmodium for malaria).

 

Question 34. A pair of fungal disease.
(a) Amoebiasis, Kala-azar
(b) Candidiasis, Athlete's foot
(c) Ascariasis, Filariasis
(d) Poliomyelitis, Amoebiasis
Answer: (b) Candidiasis, Athlete's foot
In simple words: Candidiasis and Athlete's foot are both infections caused by fungi. Other options include diseases caused by parasites or viruses.

🎯 Exam Tip: Be able to identify common fungal diseases by name, such as candidiasis (yeast infection) and Athlete's foot (tinea pedis).

 

Question 35. Plant source of Heroin is
(a) Poppy plants
(b) Cannabis plants
(c) Datura species
(d) Atropa species
Answer: (a) Poppy plants
In simple words: Heroin comes from the poppy plant. Opium, which is used to make heroin, is also taken from these plants.

🎯 Exam Tip: Connect heroin to its plant origin, the poppy (Papaver somniferum), as this is a fundamental fact in understanding drug sources.

 

Question 36. The test that confirms HIV positive is
(a) Western blot
(b) Northern blot
(c) Southern blot
(d) All the options
Answer: (a) Western blot
In simple words: The Western blot test is used to confirm if someone is HIV positive. It works by finding specific antibodies that the body makes when it fights the HIV virus.

🎯 Exam Tip: While ELISA is often used as an initial screening test for HIV, the Western blot is the confirmatory test due to its higher specificity in detecting HIV antibodies.

 

Question 37. Bacillary dysentery is caused due to.
(a) Salmonella
(b) Shigella
(c) Clostridium
(d) Yersinia
Answer: (b) Shigella
In simple words: Bacillary dysentery is an infection that causes severe diarrhea and is caused by bacteria from the Shigella group.

🎯 Exam Tip: Link "bacillary dysentery" directly with the bacterium "Shigella," as this is the primary causative agent for this specific type of diarrheal illness.

 

Question 38. Cocaine is a potent.
(a) Sedative
(b) Hallucinogen
(c) pain reliever
(d) neurotransmitter
Answer: (b) Hallucinogen
In simple words: Cocaine is a strong substance that acts as a stimulant and can also cause people to see or hear things that are not there, meaning it acts as a hallucinogen.

🎯 Exam Tip: Classify drugs based on their primary effects; cocaine is known for its stimulating properties but can also induce hallucinogenic effects at higher doses.

 

Question 39. Alkaloid found in tobacco is.
(a) Atropine
(b) cocaine
(c) heroin
(d) nicotine
Answer: (d) nicotine
In simple words: Nicotine is the main chemical in tobacco. It is an alkaloid, which is a type of natural compound that has strong effects on the body.

🎯 Exam Tip: Identify nicotine as the highly addictive alkaloid responsible for many of tobacco's effects on the human body.

 

Question 40. is a chronic memory disorder due to alcohol misuse.
(a) Cushing's syndrome
(b) Turners' syndrome
(c) Klinefelters' syndrome
(d) Korsakoff syndrome
Answer: (d) Korsakoff syndrome
In simple words: Korsakoff syndrome is a serious memory problem that happens when people drink too much alcohol for a long time. It affects their ability to remember new things.

🎯 Exam Tip: Recognize Korsakoff syndrome as a specific neurological disorder linked to chronic alcohol abuse, primarily affecting memory due to thiamine deficiency.

12th Bio Zoology Guide Human Health And Diseases Two Marks Questions And Answers

 

Question 1. What steps should be taken to maintain good health?
Answer: To stay healthy, it's very important to follow good personal hygiene, exercise regularly, and eat a balanced diet. These habits work together to strengthen your body and protect against diseases.
In simple words: Good hygiene, regular exercise, and a balanced diet are key for good health.

🎯 Exam Tip: When listing ways to maintain good health, focus on a holistic approach that includes physical activity, nutrition, and cleanliness.

 

Question 2. Define disease.
Answer: A disease can be described as a problem or poor functioning of the mind or body. It involves changes in the body's structure, how it works, and how a person feels emotionally. These issues can be caused by things in the environment, germs, inherited problems, or lifestyle choices.
In simple words: A disease is when the mind or body doesn't work right, causing physical, mental, or emotional problems.

🎯 Exam Tip: A comprehensive definition of disease should cover its impact on physical, physiological, and psychological well-being, as well as its varied etiologies.

 

Question 3. According to the WHO, what is health?
Answer: The World Health Organization (WHO) defines health as a state where a person is completely well physically, mentally, and socially, not just free from sickness or weakness. This definition highlights that health is more than just the absence of illness.
In simple words: WHO says health is a complete state of physical, mental, and social well-being, not just not being sick.

🎯 Exam Tip: Quote the WHO definition of health accurately, emphasizing its holistic nature beyond merely the absence of disease.

 

Question 4. Differentiate between infectious and non-infections disease.
Answer:
Infectious disease: These are illnesses that can spread from one person to another. For example, the common cold.
Non-infectious disease: These illnesses do not spread from one person to another. For example, anemia.
In simple words, infectious diseases are contagious, while non-infectious diseases are not.
In simple words: Infectious diseases can spread between people, like a cold. Non-infectious diseases cannot spread, like anemia.

🎯 Exam Tip: When differentiating, always provide a clear definition for each term and give a relevant example for both infectious and non-infectious diseases.

 

Question 5. Name any two fungal disease and helminthic disease.
Answer: Two fungal diseases are Candidiasis and Athlete's foot. Two helminthic diseases are Ascariasis and Filariasis. These are common examples of infections caused by fungi and parasitic worms, respectively.
In simple words: Fungal diseases include Candidiasis and Athlete's foot. Helminthic diseases are Ascariasis and Filariasis.

🎯 Exam Tip: Be ready to name specific examples of diseases caused by different types of pathogens (fungi, bacteria, viruses, helminths, protozoa).

 

Question 6. Mention the causative organism of the following.
(a) Tetanus
(b) Bubonic plague
(c) Pneumonia
(d) Cholera
Answer:
(a) Tetanus: The causative organism is Clostridium tetani.
(b) Bubonic plague: The causative organism is Yersinia pestis.
(c) Pneumonia: The causative organism is Streptococcus pneumoniae.
(d) Cholera: The causative organism is Vibrio cholerae.
Understanding the specific pathogen for each disease helps in targeted treatment.
In simple words: Tetanus is from Clostridium tetani. Plague is from Yersinia pestis. Pneumonia is from Streptococcus pneumoniae. Cholera is from Vibrio cholerae.

🎯 Exam Tip: When naming causative organisms, ensure you use the correct scientific names and understand the type of pathogen (bacteria, virus, fungus, protozoan).

 

Question 7. Classify viral disease based on the organ of infection.
Answer: Viral diseases can be classified based on the organs they infect:
(a) Pneumotropic diseases: These affect the lungs and respiratory system.
(b) Dermotropic diseases: These affect the skin.
(c) Viscerotropic diseases: These affect internal organs.
(d) Neurotropic diseases: These affect the nervous system.
This classification helps to understand the primary target of different viruses in the body.
In simple words: Viral diseases are grouped by what part of the body they attack: lungs (pneumotropic), skin (dermotropic), internal organs (viscerotropic), or brain/nerves (neurotropic).

🎯 Exam Tip: Learn the prefixes (pneumo-, dermo-, viscero-, neuro-) to quickly associate viral classifications with their respective target organs.

 

Question 8. Write the symptoms of viral hepatitis.
Answer: The symptoms of viral hepatitis include damage to the liver, yellowing of the skin and eyes (jaundice), feeling sick (nausea), fever, and pain in the stomach area. These symptoms collectively indicate inflammation and damage to the liver.
In simple words: Symptoms of viral hepatitis are liver damage, jaundice (yellow skin/eyes), nausea, fever, and stomach pain.

🎯 Exam Tip: When describing symptoms, list common and noticeable signs, particularly those characteristic of the affected organ, like jaundice for liver issues.

 

Question 9. Name the different species of malarial parasites and also mention which is the fatal one?
Answer: The different species of malarial parasites are Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium falciparum. Among these, Plasmodium falciparum is the most dangerous and causes the fatal form of malaria. This species is responsible for most malaria-related deaths.
In simple words: The malarial parasites are Plasmodium vivax, ovale, malariae, and falciparum. Plasmodium falciparum is the one that causes deadly malaria.

🎯 Exam Tip: It is crucial to remember Plasmodium falciparum as the species responsible for the most severe and fatal forms of malaria, which can lead to cerebral malaria.

 

Question 10. Name the causative agent and confirmatory test for Typhoid.
Answer: Typhoid is caused by the bacterium Salmonella typhi. The confirmatory test used to diagnose typhoid is the Widal test. This test detects specific antibodies in the blood, indicating a current or past infection.
In simple words: Typhoid is caused by Salmonella typhi bacteria. The Widal test is used to confirm if someone has typhoid.

🎯 Exam Tip: Accurately linking "Typhoid" with "Salmonella typhi" and the "Widal test" is essential for a complete answer on its diagnosis.

 

Question 11. Mention the three phases in the life of plasmodium parasite with their respective host.
Answer: The three main phases in the life cycle of the Plasmodium parasite and their hosts are:
(a) Schizogony: This phase occurs in humans.
(b) Gamogony: This phase also occurs in humans.
(c) Sporogony: This phase takes place in the gut of a mosquito.
Each phase is crucial for the parasite's survival and transmission between hosts.
In simple words: Plasmodium has three life phases: Schizogony and Gamogony happen in humans, and Sporogony happens in the mosquito's gut.

🎯 Exam Tip: Understand which stages of the Plasmodium life cycle occur in the human host (asexual reproduction and gamete formation) and which occur in the mosquito vector (sexual reproduction and spore formation).

 

Question 12. What causes shivering in malarial patient?
Answer: Shivering in a malarial patient happens when red blood cells (RBCs) infected with the sporozoite parasite burst open. When these cells rupture, they release a toxic substance called haemozoin. This release causes sudden shivering, chills, and a high fever, followed by sweating, marking the paroxysm of malaria.
In simple words: Shivering in malaria patients is caused by a toxic substance called haemozoin. This is released when red blood cells infected with the parasite burst.

🎯 Exam Tip: Key terms to include are "haemozoin" and the "rupturing of infected red blood cells" to fully explain the malarial paroxysms.

 

Question 13. Malaria Eradication programme launched by WHO is a failure. Why?
Answer: The Malaria Eradication programme started by the World Health Organization (WHO) in the 1950s was not successful. This failure was mainly due to two reasons: the Plasmodium parasite developed resistance to the anti-malarial drugs used to treat it, and mosquitoes also became resistant to DDT and other insecticides. These resistances made it very hard to control the disease effectively.
In simple words: The WHO's malaria program failed because the parasite became resistant to medicines and mosquitoes became resistant to insecticides like DDT.

🎯 Exam Tip: Highlight the two main factors for the program's failure: drug resistance by the parasite and insecticide resistance by the mosquito vector.

 

Question 14. Filarial worm and Plasmodium both are digenic parasites. Man is a common host for both parasites. Name the other host.
Answer: Both the filarial worm (causing filariasis) and Plasmodium (causing malaria) are digenic parasites, meaning they need two different hosts to complete their life cycle. While humans are a common host for both, the other host for the filarial worm is the female Culex mosquito. For Plasmodium, the other host is the female Anopheles mosquito. These mosquitoes act as vectors, transferring the parasites between human hosts.
In simple words: Humans are one host for both filarial worms and Plasmodium. The other host for filarial worms is the female Culex mosquito, and for Plasmodium, it's the female Anopheles mosquito.

🎯 Exam Tip: Differentiating between the mosquito vectors for filariasis (Culex) and malaria (Anopheles) is a common point of confusion, so ensure accuracy.

 

Question 15. Name the causative organism of filariasis and mention the site of infection of parasite.
Answer: The causative organism of filariasis is Wuchereria bancrofti, commonly known as the filarial worm. The main site of infection for this parasite is the lymph vessels and lymph nodes in the human body. The adult worms live in these areas, causing blockages and inflammation.
In simple words: Filariasis is caused by the filarial worm, Wuchereria bancrofti. It mainly infects the lymph vessels and lymph nodes.

🎯 Exam Tip: Remember both the scientific name of the parasite (Wuchereria bancrofti) and its specific location within the host (lymphatic system) for a complete answer.

 

Question 16. What do you mean by the term personal hygiene?
Answer: Personal hygiene means keeping your body clean by doing things like bathing, washing your hands, trimming your fingernails, and wearing clean clothes. It also includes keeping your home and workplace, including bathrooms and toilets, clean and free from germs. Good personal hygiene helps prevent the spread of infections and promotes overall health.
In simple words: Personal hygiene means keeping yourself clean by bathing, washing hands, and wearing clean clothes, and also keeping your surroundings clean to avoid germs.

🎯 Exam Tip: Define personal hygiene broadly to include both self-care practices and maintaining a clean environment to prevent illness.

 

Question 17. Define Immunity and Susceptibility.
Answer: Immunity is the body's overall ability to fight against disease-causing germs (pathogens). It is also called disease resistance. Susceptibility, on the other hand, is the lack of this immunity, meaning the body is vulnerable and more likely to get sick when exposed to pathogens. One strengthens the body's defenses, while the other marks its weakness.
In simple words: Immunity is the body's power to fight off sickness. Susceptibility is when the body cannot fight off sickness and gets sick easily.

🎯 Exam Tip: Clearly define both terms and emphasize their contrasting meanings: immunity as protection, and susceptibility as vulnerability to disease.

 

Question 18. How skin and mucus membrane act as barriers for infections?
Answer: Our skin acts as the first line of defense, stopping harmful microbes from getting into the body. The skin's surface is slightly acidic (pH 3-5), which makes it a tough place for many microbes to grow. This natural acidity helps keep infections away. Also, mucus membranes, found in many parts of the body like the nose and throat, trap foreign microorganisms and prevent them from attaching to body cells. This dual protection helps our bodies stay healthy.
In simple words: Skin stops germs with its acidic surface, and mucus traps them, both preventing infections.

🎯 Exam Tip: When discussing barriers, remember to mention both the physical (like skin layers) and chemical (like pH or mucus) aspects for a complete answer.

 

Question 19. What is diapedesis?
Answer: Diapedesis is a process where white blood cells, especially phagocytic cells, move out of blood vessels and into the surrounding tissues at sites of infection or inflammation. When tissues are damaged or infected, chemical signals like serotonin, histamine, and prostaglandins are released. These signals cause the nearby blood vessels to become more permeable, allowing the phagocytic cells to squeeze through the vessel walls and gather in the affected area to fight the infection. This movement is crucial for the immune response.
In simple words: Diapedesis is when special immune cells leave blood vessels to reach infected areas, guided by chemical signals.

🎯 Exam Tip: Focus on the movement of white blood cells from blood vessels to tissue during inflammation, and mention key chemical signals involved.

 

Question 20. Write any two differences between CMI and AMI.
Answer:
**Cell-Mediated Immunity (CMI):**
• In CMI, pathogens are destroyed directly by cells without producing antibodies.
• This type of immunity is mainly carried out by T cells, macrophages, and natural killer (NK) cells.
**Antibody-Mediated Immunity (AMI):**
• In AMI, pathogens are destroyed by special proteins called antibodies, which are produced by immune cells.
• This immunity is mainly carried out by B cells, T helper cells, and Antigen-Presenting Cells (APCs).
CMI is more effective against intracellular pathogens and cancer cells, while AMI targets extracellular pathogens and toxins.
In simple words: CMI fights germs directly using cells, without making antibodies. AMI uses special proteins called antibodies to fight germs.

🎯 Exam Tip: Clearly state whether antibodies are involved or not, and name the main cell types responsible for each type of immunity.

 

Question 21. Define haematopoiesis.
Answer: Haematopoiesis is the biological process by which all types of blood cells, including red blood cells, white blood cells, and platelets, are produced. This complex process primarily occurs in the bone marrow in adults, starting from hematopoietic stem cells that differentiate into various specialized blood cells. This continuous production is vital for replacing old cells and maintaining a healthy blood supply.
In simple words: Haematopoiesis is how our body makes all kinds of blood cells, mainly in the bone marrow.

🎯 Exam Tip: Remember to mention that it's the production of ALL blood cells and primarily happens in the bone marrow for adults.

 

Question 22. Which is the primary lymphoid organs of birds? Mention its location and role.
Answer: The primary lymphoid organ of birds is the Bursa of Fabricius. It is located on the dorsal side of the cloaca, a common opening for digestive, urinary, and reproductive tracts in birds. This organ is where B lymphocytes (B cells) mature and develop their ability to produce antibodies, which are crucial for humoral immunity.
In simple words: For birds, the main immune organ is the Bursa of Fabricius, located near the cloaca. It helps B cells learn to make antibodies.

🎯 Exam Tip: Specify "Bursa of Fabricius" as the organ and clearly state its role in B cell maturation for humoral immunity in birds.

 

Question 23. What are the primary lymphoid organs of mammals?
Answer: The primary lymphoid organs in mammals are the bone marrow and the thymus gland. These organs are where lymphocytes (B cells and T cells) are formed and mature into immunocompetent cells, meaning they learn to recognize specific antigens without causing harm to the body's own cells. Both bone marrow and thymus play distinct but essential roles in building a strong immune system.
In simple words: In mammals, the main immune organs are the bone marrow and the thymus gland, where immune cells are made and grow strong.

🎯 Exam Tip: List both bone marrow and thymus and briefly state their function in lymphocyte formation and maturation.

 

Question 24. What are Peyer's patches?
Answer: Peyer's patches are small, oval-shaped areas of lymphoid tissue that are found in the lining of the small intestine, specifically in the ileum. They are an important part of the body's immune system, especially in the gut. These patches contain various immune cells like macrophages, dendritic cells, T cells, and B cells, which help to monitor and respond to harmful substances and pathogens that enter the digestive system, acting as a crucial defense against foodborne invaders.
In simple words: Peyer's patches are immune tissue in the small intestine that check for germs in food.

🎯 Exam Tip: Locate Peyer's patches in the small intestine (ileum) and describe their role in gut immunity.

 

Question 25. Point out any four peripheral lymphoid organs.
Answer: Four important peripheral lymphoid organs are:
1. Lymph nodes
2. Spleen
3. Tonsils
4. MALT (Mucosa-Associated Lymphoid Tissue)
These organs are where mature lymphocytes encounter antigens and become activated to launch an immune response. They act as "meeting points" for immune cells and foreign invaders.
In simple words: Lymph nodes, spleen, tonsils, and MALT are places where immune cells meet germs and start fighting them.

🎯 Exam Tip: Simply listing the four organs clearly is usually sufficient for this type of question. Adding a brief function shows deeper understanding.

 

Question 26. Write a brief note on GALT.
Answer: GALT stands for Gut-Associated Lymphoid Tissue. It is a vital part of the immune system found in the lining of the digestive tract. GALT helps protect the body from harmful substances and pathogens that enter through food or drink. It works by having many immune cells ready to detect and respond to invaders, forming a strong defense system right where many foreign agents first encounter the body.
In simple words: GALT is immune tissue in the gut that protects us from germs we eat or drink.

🎯 Exam Tip: Define GALT by its full form, mention its location in the gut lining, and state its protective role against ingested pathogens.

 

Question 27. Why secondary immune response is more effective than primary immune response?
Answer: The secondary immune response is much more effective than the primary response because of immunological memory. After the first exposure to an antigen, the immune system "remembers" it by producing memory cells. When the body encounters the same antigen a second time, these memory cells quickly activate, leading to a faster, stronger, and more sustained production of antibodies. This rapid and powerful response helps to eliminate the pathogen more efficiently, often preventing illness.
In simple words: The body remembers germs after the first time. So, the next time it sees the same germ, it fights much faster and stronger.

🎯 Exam Tip: The key phrases here are "immunological memory" and the resulting "faster, stronger, and more sustained antibody production."

 

Question 28. Name the Agranulocytes involved in immune response.
Answer: The agranulocytes involved in the immune response are:
(a) Lymphocyte
(b) Monocytes
These white blood cells have non-granular cytoplasm and play crucial roles in specific immunity and phagocytosis, respectively. They are essential for fighting infections and removing debris.
In simple words: Lymphocytes and monocytes are types of white blood cells without granules that help fight infections.

🎯 Exam Tip: Clearly list both lymphocytes and monocytes as the agranulocytes, as the question asks for the name.

 

Question 29. Why dendritic cells are called so?
Answer: Dendritic cells are named for their distinctive shape, which includes long, thin membrane extensions. These extensions resemble the dendrites of nerve cells, giving the cells a branching, tree-like appearance. These cells are antigen-presenting cells (APCs) that capture antigens and present them to T-helper cells, playing a crucial role in initiating specific immune responses. Their unique shape helps them to effectively interact with other immune cells and antigens.
In simple words: Dendritic cells are named "dendritic" because they have long, branch-like arms, much like nerve cell dendrites.

🎯 Exam Tip: Relate the name "dendritic" to their characteristic branching, tree-like extensions and briefly mention their role in presenting antigens.

 

Question 30. How many dendritic cells are identified? Name them.
Answer: Four main types of dendritic cells have been identified:
1. Langerhans cells (found in the skin)
2. Interstitial cells (found in most organs)
3. Myeloid cells
4. Lymphoid cells
Each type plays a specialized role in different tissues, contributing to the body's overall immune surveillance. These cells are crucial for triggering adaptive immune responses by presenting antigens.
In simple words: There are four kinds of dendritic cells: Langerhans, interstitial, myeloid, and lymphoid cells.

🎯 Exam Tip: List the four types of dendritic cells, and if possible, include a key location like Langerhans cells in the skin.

 

Question 31. What are Haptens?
Answer: Haptens are small molecules that, by themselves, cannot trigger an immune response (they are non-immunogenic). However, if a hapten attaches to a larger carrier protein, the combined complex can then induce an immune response. Once the immune system is sensitized to the hapten, it can react with the hapten even when it is not attached to a carrier. Many common allergens and drugs can act as haptens.
In simple words: Haptens are small things that can't start an immune reaction alone but can when attached to a bigger protein.

🎯 Exam Tip: Key points are that haptens are small, non-immunogenic alone, but become immunogenic when bound to a carrier protein.

 

Question 32. Distinguish between Epitope and Paratope.
Answer:
**Epitope:** An epitope is the specific part of an antigen molecule that is recognized by the immune system and where an antibody or T cell receptor binds. It's like a unique flag on the antigen that the immune system looks for. Each antigen can have multiple epitopes.
**Paratope:** A paratope is the specific antigen-binding site found on an antibody molecule or a T cell receptor. It is the part that actually recognizes and binds to an epitope on an antigen. The paratope's shape is complementary to the epitope, allowing for a precise fit.
Simply put, the epitope is on the pathogen, and the paratope is on the immune cell/antibody that recognizes it.
In simple words: An epitope is the part of a germ that immune cells see. A paratope is the part of an immune cell that grabs onto the germ's epitope.

🎯 Exam Tip: Clearly define each term and state where it is located (epitope on antigen, paratope on antibody/receptor) and its function in binding.

 

Question 33. Draw a simplified diagram of immunoglobulin.
Answer:
The diagram below shows the basic Y-shaped structure of an immunoglobulin (antibody) molecule with its key components.

In simple words: An immunoglobulin looks like a 'Y' shape with different parts for holding antigens, made of heavy and light chains connected by bonds.

🎯 Exam Tip: For diagrams, ensure clear labels for all important parts (heavy/light chains, variable/constant regions, antigen-binding site, disulfide bonds) and maintain a neat, proportionate drawing.

 

Question 34. On which basis, the antibodies are classified? Name them.
Answer: Antibodies are classified into five major categories based on their physiological and biochemical properties, meaning how they work and what they are made of. These categories are also called isotypes. The five classes of antibodies are:
1. IgG (gamma)
2. IgM (mu)
3. IgA (alpha)
4. IgD (delta)
5. IgE (epsilon)
Each class plays a specific role in the immune system, defending the body in different ways and in different locations.
In simple words: Antibodies are grouped into five main types based on their features: IgG, IgM, IgA, IgD, and IgE.

🎯 Exam Tip: Remember to name all five classes of antibodies and state that their classification is based on their unique properties and functions.

 

Question 35. Name any four functions of antibodies.
Answer: Antibodies perform several important functions in the immune system to fight off pathogens. Four key functions are:
1. **Agglutination:** Clumping together antigens or pathogens, making them easier for other immune cells to clear.
2. **Precipitation:** Making soluble antigens insoluble, causing them to fall out of solution and become easier to remove.
3. **Opsonization:** Coating pathogens, which marks them for destruction by phagocytic cells (like macrophages) that "eat" invaders.
4. **Neutralization:** Blocking the harmful effects of toxins or preventing viruses and bacteria from binding to host cells, thus stopping them from causing infection.
These diverse mechanisms ensure effective defense against various threats.
In simple words: Antibodies can clump germs, make them settle, mark them for eating, or stop them from harming cells.

🎯 Exam Tip: List the functions clearly and briefly explain what each action does to help eliminate pathogens.

 

Question 36. Which type of bonds are developed between an antigen and antibody? Name them.
Answer: The bonds that form between an antigen and an antibody at their combining site are all non-covalent. This means they are not strong, permanent chemical bonds but rather weaker, reversible interactions that allow for specific recognition. These non-covalent bonds include:
1. Hydrogen bonds
2. Electrostatic bonds (ionic interactions)
3. Van der Waals forces
4. Hydrophobic bonds (interactions between non-polar regions)
The combined effect of these many weak interactions results in a strong and specific binding affinity.
In simple words: Antigens and antibodies connect using weak, temporary bonds like hydrogen bonds, electrostatic bonds, Van der Waals forces, and hydrophobic bonds.

🎯 Exam Tip: Remember that these are "non-covalent" bonds and list the specific types, as the question asks to name them.

 

Question 37. What is antibody affinity?
Answer: Antibody affinity refers to the strength of the binding interaction between a single antigen-binding site on an antibody and a single epitope (the part of the antigen it recognizes). It measures how tightly and stably an antibody binds to its target. A high affinity means a stronger and more effective binding, which is important for the immune system to efficiently neutralize pathogens or toxins.
In simple words: Antibody affinity is how strongly and tightly one part of an antibody sticks to one specific part of a germ.

🎯 Exam Tip: Define affinity as the "strength of reaction/binding" between a single antibody binding site and a single antigenic determinant.

 

Question 38. What do you mean by third generation vaccine?
Answer: Third-generation vaccines are advanced types of vaccines that are designed using modern biotechnology, often involving genetic engineering. Unlike older vaccines that use weakened or killed pathogens, these vaccines focus on specific parts of the pathogen, like DNA or recombinant proteins, to trigger an immune response. They are known for being very pure and potent, aiming to provide strong immunity with minimal side effects. The latest innovation in this category includes DNA vaccines and recombinant vaccines.
In simple words: Third-generation vaccines are new, pure vaccines made using genetic methods, like DNA vaccines, to teach the body to fight specific germs.

🎯 Exam Tip: Emphasize that these are "genetically engineered" or "recombinant" vaccines and mention their high purity/potency, with DNA vaccines as a key example.

 

Question 39. Define vaccination.
Answer: Vaccination is the process of introducing a vaccine into the body to produce immunity against a specific infectious disease. A vaccine contains weakened or inactive forms of a pathogen, or parts of it, which train the immune system to recognize and fight the real pathogen without causing illness. This controlled exposure allows the body to develop protective memory cells and antibodies, preparing it for future encounters with the disease.
In simple words: Vaccination is when we get a shot with a vaccine to teach our body how to fight a certain disease without getting sick.

🎯 Exam Tip: The definition must include administering a vaccine to "produce immunity" against a "specific disease."

 

Question 40. Define allergy and allergen.
Answer:
**Allergy:** Allergy is an exaggerated or over-reactive response of the immune system to certain harmless substances present in the environment. Instead of ignoring these substances, the immune system mistakenly identifies them as threats, leading to symptoms like sneezing, itching, or skin rashes.
**Allergen:** An allergen is any substance that triggers an allergic reaction in a susceptible person. Common allergens include pollen, dust mites, pet dander, certain foods, or insect stings. These substances are usually harmless to most people but cause an immune response in those with allergies.
Understanding both terms is crucial for managing allergic conditions.
In simple words: Allergy is when the body overreacts to something harmless. An allergen is the harmless thing that causes this overreaction.

🎯 Exam Tip: Clearly state that allergy is an "exaggerated immune response" and an allergen is the "substance" that causes it.

 

Question 41. What is Anaphylaxis?
Answer: Anaphylaxis is a severe, life-threatening allergic reaction that happens very quickly. It is an immediate hypersensitivity reaction that can affect multiple body systems simultaneously, leading to symptoms like difficulty breathing, a sudden drop in blood pressure, swelling, and hives. This severe reaction is caused by the rapid release of chemicals from immune cells, often triggered by things like insect stings, certain foods, or medications. It requires immediate medical attention.
In simple words: Anaphylaxis is a very serious, fast-acting allergic reaction that can be dangerous and needs urgent medical help.

🎯 Exam Tip: Highlight that anaphylaxis is a "sudden, severe, and systemic (affecting the whole body)" hypersensitivity reaction that is life-threatening.

 

Question 42. Expand (a) MALT (b) NACO
Answer:
(a) MALT stands for **Mucosal-Associated Lymphoid Tissue**. This tissue is a part of the immune system found in mucous membranes throughout the body, like in the digestive, respiratory, and urogenital tracts, protecting them from pathogens.
(b) NACO stands for **National AIDS Control Organisation**. This is an organization in India that works to control and prevent the spread of HIV/AIDS through various programs and initiatives.
Both organizations play crucial roles in health and disease prevention.
In simple words: MALT is immune tissue found in body linings like the gut. NACO is an organization that fights against AIDS.

🎯 Exam Tip: Ensure correct spelling and full expansion for both acronyms. Briefly state the purpose of each.

 

Question 43. How will you define Autoimmunity?
Answer: Autoimmunity is a condition where the body's immune system mistakenly attacks its own healthy cells and tissues, rather than foreign invaders. Normally, the immune system can tell the difference between "self" (the body's own cells) and "non-self" (pathogens). In autoimmunity, this ability to distinguish self from non-self fails, leading the immune system to launch an abnormal response against its own body. This can cause various autoimmune diseases, affecting different organs and systems.
In simple words: Autoimmunity is when our immune system wrongly attacks our own healthy body parts instead of germs.

🎯 Exam Tip: The core of autoimmunity is the immune system "failing to distinguish self from non-self" and "attacking its own body."

 

Question 44. What do you mean by drug abuse?
Answer: Drug abuse refers to the use of certain drugs for purposes other than their intended medical use, or in amounts and frequencies that harm a person's physical, mental, or social well-being. It involves a pattern of harmful use of any substance for mood-altering purposes. This behavior can lead to serious health problems, addiction, and negatively impact daily life and relationships.
In simple words: Drug abuse is using drugs in a way that harms your body, mind, or life, rather than for proper medical reasons.

🎯 Exam Tip: Define drug abuse as using drugs for "non-medical purposes" and highlight the "impairment of physical, physiological, and psychological functions."

 

Question 45. Name any 4 natural cannabinoids.
Answer: Four natural cannabinoids are:
1. Marijuana
2. Ganja
3. Hashish
4. Charas
These substances are derived from the cannabis plant and contain psychoactive compounds that interact with the body's cannabinoid receptors, leading to various effects on the mind and body. They have been used for different purposes, but their abuse can lead to health issues.
In simple words: Marijuana, Ganja, Hashish, and Charas are four types of natural cannabinoids that come from the cannabis plant.

🎯 Exam Tip: Simply list four distinct names of natural cannabinoids found in the cannabis plant.

 

Question 46. Mention any two drugs to treat insomnia patient.
Answer: Two drugs commonly used to treat insomnia patients are:
1. Methamphetamine (though primarily a stimulant, it can be prescribed in specific, rare cases for severe conditions, but often has abuse potential)
2. Lysergic acid diethylamide (LSD) (This is incorrect. LSD is a hallucinogen and not used to treat insomnia. Common drugs for insomnia are benzodiazepines like temazepam or non-benzodiazepine hypnotics like zolpidem.)
*Correction Note: The source provided incorrect examples for insomnia treatment. Typical drugs for insomnia are hypnotics, not stimulants or hallucinogens. The most common types are benzodiazepines and Z-drugs.*
**Corrected Answer based on typical medical practice:**
Two drugs commonly used to treat insomnia patients are:
1. Benzodiazepines (e.g., Temazepam)
2. Non-benzodiazepine hypnotics (e.g., Zolpidem, Zopiclone)
These medications help induce sleep or maintain sleep by affecting neurotransmitters in the brain, providing temporary relief for individuals struggling with sleep disorders.
In simple words: Drugs like benzodiazepines and non-benzodiazepine hypnotics are used to help people with insomnia sleep better.

🎯 Exam Tip: Mention two classes of drugs or specific examples (e.g., benzodiazepines or Z-drugs) that are actually prescribed for insomnia, as accurate medical information is crucial.

 

Question 47. Name the antibody responsible for allergic reaction. Also mention two chemicals released during allergic response.
Answer: The antibody responsible for allergic reactions is **IgE (epsilon)**. When a person is exposed to an allergen, IgE antibodies bind to mast cells, triggering the release of certain chemicals. The two primary chemicals released during an allergic response are:
1. **Histamine**
2. **Serotonin**
These chemicals cause the common symptoms of allergies, such as itching, swelling, and redness, by increasing blood flow and fluid leakage from capillaries.
In simple words: IgE antibody causes allergies, and during an allergic reaction, chemicals like histamine and serotonin are released.

🎯 Exam Tip: Clearly state IgE as the antibody and histamine and serotonin as the two key chemicals. This covers all parts of the question.

 

Question 48. Name an opioid drug and its source plant. How it is useful in medical field?
Answer: An opioid drug is Morphine, and its source plant is the opium poppy plant (*Papaver somniferum*). Morphine is widely used in the medical field as a strong painkiller. It works by binding to opioid receptors in the brain and spinal cord, reducing the perception of pain. Doctors often use it to manage severe pain, such as after surgery, during cancer treatment, or following serious injuries, providing much-needed relief to patients.
In simple words: Morphine is an opioid drug from the poppy plant. It is used as a very strong painkiller in hospitals.

🎯 Exam Tip: Name Morphine, its source (poppy plant), and its primary medical use as a strong analgesic (painkiller).

 

Question 49. What is withdrawal symptom? Name any two symptoms.
Answer: Withdrawal symptoms are the physical and mental effects that occur when a person who has been regularly taking a drug or alcohol suddenly stops or significantly reduces their intake. The body, having adapted to the substance, reacts negatively to its absence. This process can be very uncomfortable and distressing. Two common withdrawal symptoms are:
1. **Nervousness**
2. **Insomnia** (difficulty sleeping)
Other symptoms can include tremors, anxiety, sweating, and even seizures, depending on the substance and the level of dependence.
In simple words: Withdrawal symptoms are bad feelings when someone stops taking a drug or alcohol they used regularly. Two symptoms are nervousness and trouble sleeping.

🎯 Exam Tip: Define withdrawal as the body's reaction to stopping a substance and provide two clear, distinct examples of symptoms.

 

Question 50. Name the plant source of Cocaine and Heroin.
Answer: The plant sources for Cocaine and Heroin are:
1. Cocaine is obtained from the leaves of the **Erythroxylum coca** plant, commonly known as the coca plant.
2. Heroin is obtained from the **poppy plant** (*Papaver somniferum*), specifically by processing morphine, which is extracted from the poppy's sap.
Both plants contain potent psychoactive compounds that have been historically used but are also widely abused due to their addictive properties.
In simple words: Cocaine comes from the coca plant, and Heroin comes from the poppy plant.

🎯 Exam Tip: Clearly state the plant source for each drug. Specific botanical names are a plus.

 

Question 51. What is Liver cirrhosis?
Answer: Liver cirrhosis is a severe and irreversible scarring of the liver, often caused by long-term damage from conditions like chronic alcohol abuse, hepatitis, or fatty liver disease. In this condition, healthy liver cells are gradually replaced by scar tissue, which prevents the liver from functioning properly. This scarring interferes with the liver's ability to process nutrients, filter blood, and produce important proteins. As the scarring worsens, liver function declines, leading to serious health complications.
In simple words: Liver cirrhosis is when the liver gets badly scarred and stops working well, often because of too much alcohol or other long-term damage.

🎯 Exam Tip: Define cirrhosis as "scarring of the liver" and mention its impact on liver function, often linking it to alcohol or chronic liver damage.

 

Question 52. Define Korsakoff syndrome.
Answer: Korsakoff syndrome is a severe chronic memory disorder that is most commonly caused by long-term, heavy alcohol misuse, especially when combined with a deficiency of thiamine (vitamin B1). People with this syndrome struggle to form new memories (anterograde amnesia) and may fill in memory gaps with fabricated stories (confabulation). It results from damage to specific areas of the brain that are essential for memory formation.
In simple words: Korsakoff syndrome is a serious memory problem, usually from heavy alcohol use and lack of vitamin B1, where people can't make new memories.

🎯 Exam Tip: Highlight that it's a "chronic memory disorder" primarily caused by "alcohol misuse" linked to "thiamine deficiency."

 

Question 53. What are the benefits of exercising our body?
Answer: Participating in a regular exercise program offers numerous benefits for both physical and mental well-being:
• It helps to increase self-esteem and body image.
• It can boost self-confidence and a sense of accomplishment.
• Exercise helps create a sense of empowerment by improving physical capabilities.
• It can enhance social connections and relationships, especially in group activities.
Beyond these, exercise also improves cardiovascular health, strengthens muscles, helps manage weight, and reduces stress, contributing to an overall healthier and happier life.
In simple words: Exercising makes you feel better about yourself, gives you confidence, makes you feel stronger, and helps you connect with others.

🎯 Exam Tip: List a few distinct benefits, covering both mental/emotional aspects (self-esteem, confidence) and social aspects, to show a broad understanding.

12th Bio Zoology Guide Human Health and Diseases Three Marks Questions and Answers

 

Question 54. Write the name of causative agent, infection site, mode of transmission and any two symptoms of Chikungunya.
Answer:
**Causative Agent:** Chikungunya virus (an Alpha virus)
**Infection Site:** Primarily affects the nervous system, joints, and muscles.
**Mode of Transmission:** Transmitted to humans through the bite of infected *Aedes aegypti* mosquitoes.
**Two Symptoms:**
1. Fever
2. Severe joint pain and swelling (often in the hands and feet)
Other symptoms can include headache, muscle pain, and rash, with the joint pain often being debilitating and long-lasting.
In simple words: Chikungunya is caused by an Alpha virus, affects the nervous system, and is spread by Aedes mosquitoes. Symptoms include fever and severe joint pain.

🎯 Exam Tip: Be precise with the causative agent (virus type), vector (mosquito species), and clearly list at least two common symptoms as requested.

 

Question 55. Draw and label the parts of Entamoeba histolytica.
Answer:
Below is a simplified diagram illustrating the key parts of *Entamoeba histolytica*, the parasite responsible for amoebiasis.

In simple words: This diagram shows the key internal parts of the Entamoeba histolytica cell, like its nucleus, food vacuoles, and different cytoplasm layers.

🎯 Exam Tip: Ensure clear and accurate labeling of the nucleus, cytoplasm regions (ectoplasm/endoplasm), food vacuoles, and the outer membrane (plasmalemma).

 

Question 56. Give a brief account of Kala-azar.
Answer: Kala-azar, also known as visceral leishmaniasis, is a serious parasitic disease caused by the parasite *Leishmania donovani*. It is spread to humans through the bite of an infected sandfly (*Phlebotomus*). Once in the body, the parasites infect and multiply in immune cells called macrophages, mainly in the endothelial cells, bone marrow, liver, and spleen. Symptoms include weight loss, anemia, prolonged fever, and enlargement of the spleen and liver. If not treated, Kala-azar is often fatal, making early diagnosis and treatment crucial.
In simple words: Kala-azar is a severe disease caused by a parasite called *Leishmania donovani*, spread by sandflies. It causes fever, weight loss, and swelling of the spleen and liver.

🎯 Exam Tip: Key points include the causative parasite (*Leishmania donovani*), the vector (sandfly), major organs affected (spleen, liver, bone marrow), and characteristic symptoms (fever, weight loss, organ enlargement).

 

Question 57. Comment on Malaria vaccine.
Answer: Developing an effective malaria vaccine has been a significant challenge due to the complex life cycle of the malaria parasite. As of 2015, the only approved vaccine is RTS,S (Mosquirix). This vaccine requires four injections and has relatively low efficacy, ranging from 26-50%. Due to its limited effectiveness, the World Health Organization (WHO) does not recommend its widespread use for infants between 6 to 12 weeks of age. However, it is being used in some areas to protect children. Research continues to improve malaria vaccines, which could be a major tool in controlling this widespread disease.
In simple words: The only approved malaria vaccine, RTS,S, needs four shots and isn't very effective, so it's not widely recommended by WHO for very young babies.

🎯 Exam Tip: Mention the name of the approved vaccine (RTS,S), its relatively low efficacy, the number of doses, and the WHO's cautious recommendation.

 

Question 58. What is innate immunity?
Answer: Innate immunity is the body's natural, first-line defense system against pathogens. It is present from birth and acts immediately to protect the body without needing prior exposure to an antigen. This type of immunity is non-specific, meaning it provides general protection against a wide range of infectious agents rather than targeting specific ones. It involves various physical barriers (like skin), chemical defenses (like stomach acid), and immune cells (like phagocytes) that work together to prevent infection.
In simple words: Innate immunity is our body's natural defense that we are born with. It acts fast and generally against all germs, not specific ones.

🎯 Exam Tip: Key aspects are "natural phenomenon," "present from birth," "non-specific," and acting as the "first line of defense."

 

Question 59. Explain (a) Cell Mediated Immunity (b) Antibody Mediated Immunity
Answer:
(a) **Cell-Mediated Immunity (CMI):** This type of immunity involves specialized immune cells directly attacking infected cells or pathogens, without using antibodies. It is primarily carried out by T cells (like cytotoxic T cells) and other cells such as macrophages and natural killer (NK) cells. CMI is crucial for fighting intracellular pathogens like viruses and certain bacteria, as well as cancer cells and transplanted tissues.
(b) **Antibody-Mediated Immunity (AMI):** Also known as humoral immunity, this defense mechanism involves the production of antibodies by B cells. These antibodies circulate in the blood and lymph, where they bind to specific pathogens or toxins outside the cells (extracellular pathogens). This binding neutralizes the threats, marks them for destruction, or clumps them together for easier clearance. AMI is effective against bacteria, viruses before they enter cells, and toxins.
Both CMI and AMI are essential for a complete and effective immune response.
In simple words: Cell-mediated immunity uses cells to fight germs directly. Antibody-mediated immunity uses special proteins called antibodies to fight germs in the blood.

🎯 Exam Tip: For each, clearly state whether antibodies are involved, name the primary cells responsible (T cells for CMI, B cells/antibodies for AMI), and mention the type of pathogens they target.

 

Question 60. Secondary response is a booster response – Explain.
Answer: The secondary immune response is often called a "booster response" because it is a much faster, stronger, and longer-lasting reaction than the primary response. This happens when the immune system encounters an antigen for the second (or subsequent) time. During the primary exposure, the body creates memory cells, which can quickly recognize the antigen. Upon re-exposure, these memory cells rapidly multiply and produce a large amount of antibodies and effector T cells, leading to a quick and effective elimination of the pathogen, often preventing the development of disease symptoms. This rapid memory response is why booster shots work.
In simple words: The secondary immune response is a strong "booster" because the body remembers germs and fights them much faster and better the second time, thanks to memory cells.

🎯 Exam Tip: Explain that the "booster" effect is due to immunological memory, resulting in a faster, stronger, and more prolonged production of antibodies upon re-exposure to an antigen.

 

Question 61. What are lymphoid organs? Mention its types.
Answer: Lymphoid organs are specialized parts of the body that are essential for the production, maturation, and activation of lymphocytes, which are the main cells of the immune system. These organs provide the environment needed for immune cells to develop and function properly.
Based on their function, lymphoid organs are classified into two main types:
1. **Primary (or Central) Lymphoid Organs:** These are where lymphocytes are formed and mature. Examples include the bone marrow (where B cells mature and all lymphocytes originate) and the thymus (where T cells mature).
2. **Secondary (or Peripheral) Lymphoid Organs:** These are the sites where mature lymphocytes encounter antigens and become activated to launch an immune response. Examples include lymph nodes, spleen, tonsils, and MALT.
Both types work together to ensure a robust and responsive immune system.
In simple words: Lymphoid organs are places where immune cells are made, grow up, and learn to fight germs. They are either primary (making cells) or secondary (fighting germs).

🎯 Exam Tip: Define lymphoid organs by their role in lymphocyte development/function and clearly list and describe the two main types with examples for each.

 

Question 62. Classify antigens based on origin.
Answer: Based on their origin, antigens are classified into two main types:
1. **Exogenous Antigens:** These are antigens that enter the host body from the outside environment. They can be in the form of microorganisms (like bacteria, viruses), pollens, dust, drugs, or pollutants. The immune system detects these foreign substances and mounts a response to eliminate them.
2. **Endogenous Antigens:** These are antigens that are produced within the cells of an individual's own body. Examples include proteins from viruses infecting the cell, or abnormal proteins produced by cancer cells, or even normal self-proteins that become targets in autoimmune diseases. Blood group antigens are also a classic example of self-antigens.
This classification helps understand how the immune system responds to different threats.
In simple words: Antigens are grouped by where they come from: "exogenous" means from outside the body (like germs), and "endogenous" means from inside the body (like virus-infected cells or abnormal proteins).

🎯 Exam Tip: Clearly define and provide examples for both exogenous (from outside) and endogenous (from inside) antigens.

 

Question 63. Point out the factors that determine the binding force between antigen - antibody reactions.
Answer: The binding force between an antigen and an antibody is determined by several non-covalent interactions and factors, which collectively contribute to the strength and specificity of their bond. The three main factors are:
1. **Closeness between Antigen and Antibody (Complementarity):** The tighter the fit between the antigen's epitope and the antibody's paratope, the stronger the binding. This shape-matching is crucial for specific recognition.
2. **Non-covalent Bonds:** The actual forces holding them together are multiple weak interactions, including hydrogen bonds, electrostatic bonds (ionic interactions), and Van der Waals forces. The more of these bonds formed, the stronger the overall attachment.
3. **Affinity of Antibody:** This refers to the intrinsic strength of the interaction between a single binding site on an antibody and a single epitope on an antigen. High affinity means a more stable and effective bond.
These factors ensure that the immune response is both precise and powerful.
In simple words: The strength of antigen-antibody binding depends on how well they fit together, the number of weak bonds between them, and how strongly the antibody wants to bind.

🎯 Exam Tip: List the three factors clearly: complementarity, multiple non-covalent bonds, and antibody affinity. Mentioning these terms shows a good understanding.

 

Question 64. Why it is important to study antigen - antibody interaction?
Answer: Studying antigen-antibody interactions is very important for several reasons, as it forms the basis for many diagnostic tools and therapies. The chief applications include:
1. **Blood Grouping for Transfusion:** Ensuring compatible blood transfusions to prevent dangerous immune reactions.
2. **Detecting Infectious Agents:** Identifying exposure to infectious diseases by looking for specific antibodies or antigens (e.g., ELISA tests for HIV).
3. **Developing Immunoassays:** Creating tests to measure various substances in the body, like hormones or drugs.
4. **Diagnosing Immunodeficiency Diseases:** Understanding specific immune problems by analyzing how antibodies react.
This knowledge also guides vaccine development and the creation of targeted treatments.
In simple words: Studying how antigens and antibodies interact helps us with blood transfusions, finding diseases, making tests for body substances, and understanding immune problems.

🎯 Exam Tip: Focus on the practical applications, such as diagnostics (blood grouping, disease detection) and therapy development, to highlight the importance of this study.

 

Question 65. Explain opsonisation property of antibodies.
Answer: Opsonization is a crucial process in the immune system where antibodies (and other molecules called opsonins) coat the surface of a pathogen, effectively marking it for destruction. When an antibody binds to a pathogen's cell membrane, it acts like a signal flag. Phagocytic cells, such as macrophages and neutrophils, have receptors that recognize these antibody-coated pathogens. This recognition triggers the phagocytes to engulf and digest the marked pathogen much more efficiently than they would otherwise. It's like putting a "eat me" sign on the pathogen, making it easier for immune cells to "clean up" the infection.
In simple words: Opsonization is when antibodies cover a germ, making it easier for immune cells to find and "eat" it, like putting a tag on it for removal.

🎯 Exam Tip: Define opsonization as "coating pathogens" and clearly explain that this "marks them for destruction" by phagocytes, increasing efficiency.

 

Question 66. Give an example for (a) First generation vaccine (b) Second generation vaccine (c) Third generation vaccine
Answer:
(a) **First generation vaccine:** An example of a first-generation vaccine is the **MMR vaccine** (Measles, Mumps, Rubella), which uses live, attenuated (weakened) viruses.
(b) **Second generation vaccine:** An example of a second-generation vaccine is the **Hepatitis-B vaccine**, which uses recombinant proteins (specifically, the Hepatitis B surface antigen) produced in yeast.
(c) **Third generation vaccine:** An example of a third-generation vaccine is a **DNA Vaccine** (e.g., some experimental HIV or influenza vaccines), which uses genetic material (DNA) from the pathogen to induce an immune response.
Each generation represents advancements in vaccine technology, aiming for better safety and efficacy.
In simple words: MMR is a first-gen vaccine. Hepatitis-B vaccine is second-gen. A DNA vaccine is an example of a third-gen vaccine.

🎯 Exam Tip: Provide one clear and distinct example for each generation, highlighting the technology used (e.g., live attenuated for first, recombinant protein for second, DNA for third).

 

Question 67. Name the diseases for which vaccines were developed by Louis Pasteur.
Answer: Louis Pasteur, a pioneering microbiologist, developed some of the earliest vaccines. The diseases for which he famously developed vaccines include:
1. **Cholera** (specifically fowl cholera)
2. **Anthrax**
3. **Rabies**
His work laid the foundation for modern vaccinology, saving countless lives by demonstrating that diseases could be prevented through inoculation with weakened forms of pathogens.
In simple words: Louis Pasteur made vaccines for diseases like cholera, anthrax, and rabies.

🎯 Exam Tip: Simply listing the three diseases (Cholera, Anthrax, Rabies) associated with Louis Pasteur's vaccine development is sufficient.

 

Question 68. How AIDS patient fail to develop immunity?
Answer: Patients with AIDS (Acquired Immunodeficiency Syndrome) fail to develop effective immunity because the Human Immunodeficiency Virus (HIV), which causes AIDS, selectively infects and destroys helper T cells (also known as CD4+ T cells). Helper T cells are crucial "commanders" of the immune system; they signal other immune cells, including B cells, to produce antibodies and killer T cells to attack infected cells. Without enough helper T cells, the immune system becomes severely weakened, losing its ability to coordinate a proper defense against even common infections, leading to immunodeficiency.
In simple words: AIDS patients can't develop immunity because the HIV virus attacks and destroys important helper T cells, which are needed to activate other immune cells.

🎯 Exam Tip: The core reason is the "selective infection and destruction of helper T cells (CD4+ T cells)" by HIV, which impairs the entire immune response.

 

Question 69. Suggest few methods to prevent AIDS.
Answer: Preventing AIDS is the best approach. Key methods include practicing safe sex and getting regular check-ups. It's also important to ensure safe blood for transfusions and use disposable needles. Using condoms during sexual contact and preventing drug abuse are also crucial. Awareness programs about AIDS, especially those run by organizations like NACO and WHO, are vital to stop its spread. Understanding transmission routes helps in adopting preventive measures effectively.
In simple words: To prevent AIDS, practice safe sex, use clean needles, and get tested regularly. Also, be aware and avoid drug abuse.

🎯 Exam Tip: When listing prevention methods for diseases like AIDS, focus on both behavioral changes and public health initiatives.

 

Question 70. State immunological surveillance theory.
Answer: The immunological surveillance theory suggests that the immune system's main job is to find and destroy abnormal, potentially cancerous cells that appear in the body due to genetic changes. If this surveillance system becomes less effective, either due to aging or immune deficiencies, the chances of developing cancer increase. So, a strong immune system actively protects us from cancer by eliminating problematic cells early. A breakdown in this protective mechanism can lead to tumor growth.
In simple words: This theory says our immune system constantly watches for and destroys cancer cells. If it stops working well, cancer can grow.

🎯 Exam Tip: Immunological surveillance highlights the immune system's role beyond fighting infections, extending to self-protection against malignancy.

 

Question 71. What is contact inhibition? How it is related to tumours growth?
Answer: Normal cells show a property called contact inhibition. This means they stop dividing when they touch other cells, preventing uncontrolled growth. Cancer cells, however, do not have this property. They continue to divide even when they are in contact with other cells. This unchecked division leads to a mass of tissues known as tumors. The loss of contact inhibition is a key characteristic of cancer cells that allows them to multiply excessively and form abnormal growths.
In simple words: Contact inhibition stops normal cells from growing too much when they touch. Cancer cells lack this, so they keep dividing and form tumors.

🎯 Exam Tip: Remember that contact inhibition is a crucial regulatory mechanism for cell growth, and its absence is a hallmark feature of cancerous transformation.

 

Question 72. Differentiate between normal cells and cancer cells.
Answer:**Normal Cells:** 1. Have small, uniformly shaped nuclei and a relatively large cytoplasm. 2. Are organized into distinct tissues with regular cell size and shape. 3. Usually have differentiated cell structures and normal cell surface markers. 4. Show lower levels of cell division and form clearly demarcated tissues. **Cancer Cells:** 1. Have large, variably shaped nuclei and a relatively small cytoplasm. 2. Exhibit variation in cell size and shape, leading to disorganized arrangements. 3. Often lose their normal specialized features and show elevated expression of certain cell markers. 4. Have a high number of dividing cells and form poorly defined tumor boundaries. The uncontrolled growth of cancer cells is a significant health concern.
In simple words: Normal cells grow in an organized way, stop when they touch, and have a regular shape. Cancer cells grow uncontrollably, have odd shapes, and keep dividing even when crowded.

🎯 Exam Tip: When differentiating, focus on the fundamental properties like growth control, nuclear morphology, and tissue organization for both cell types.

 

Question 73. Write a note on Heroin.
Answer: Heroin, also known as smack, is a strong opioid drug. Chemically, it is diacetylmorphine, appearing as a white, odorless, bitter crystalline compound. It is made by acetylating morphine, which is naturally extracted from the flowers of the poppy plant (Papaver somniferum). Heroin is highly addictive and has severe negative impacts on health. It is commonly abused for its euphoric effects.
In simple words: Heroin is a strong, bitter drug made from the poppy plant. It is very addictive and harmful.

🎯 Exam Tip: When discussing drugs, clearly state its chemical name, source, and primary effects or uses to demonstrate full understanding.

 

Question 74. "Smoking and Tobacco chewing is injurious to health” – Comment on the statement.
Answer: The statement "Smoking and Tobacco chewing is injurious to health" is absolutely true and highly important. Tobacco is used in various forms like smoking, chewing, and snuff. When smoked or chewed, it releases carbon monoxide into the blood, which reduces the amount of oxygen that can be carried by hemoglobin, causing oxygen deficiency in the body. Tobacco also contains nicotine, an addictive alkaloid, and tars, both of which severely harm the heart, lungs, and nervous system. Nicotine stimulates the adrenal glands to release adrenaline and noradrenaline, increasing blood pressure and heart rate. These effects contribute to serious health problems like cancer, heart disease, and respiratory issues.
In simple words: This statement is true because tobacco, whether smoked or chewed, has harmful chemicals like nicotine and carbon monoxide. These substances damage the heart, lungs, and nerves, leading to many diseases.

🎯 Exam Tip: When commenting on such statements, always provide specific examples of harmful substances and their physiological effects on the body.

 

Question 75. Point out the symptoms of mental depression.
Answer: Mental depression is a serious mood disorder characterized by several symptoms that affect how a person feels, thinks, and behaves. Common signs and symptoms of mental depression include:

• Loss of self-confidence and self-esteem.
• Constant feelings of anxiety or nervousness.
• An inability to enjoy things that were once pleasurable or interesting.

Other symptoms can include persistent sadness, changes in appetite or sleep patterns, fatigue, and difficulty concentrating. Early recognition of these symptoms is crucial for effective treatment.
In simple words: Symptoms of depression include losing confidence, feeling anxious often, and not enjoying things you used to like.

🎯 Exam Tip: When listing symptoms for mental health conditions, try to include a mix of emotional, cognitive, and behavioral indicators.

12th Bio Zoology Guide Human Health and Diseases Five Marks Questions

 

Question 76. Name any five viral diseases, their causative agents, infection site, mode of transmission and their symptoms.
Answer:

These viral diseases highlight the diverse ways viruses can affect the body and spread among individuals.
In simple words: This table lists five viral diseases, showing what causes them, where they affect the body, how they spread, and their symptoms.

🎯 Exam Tip: When asked to list multiple diseases and their characteristics, organize your answer clearly, preferably in a table, to ensure all requested details are included.

 

Question 77. Describe the life cycle of plasmodium parasite.
Answer: Plasmodium vivax, the malarial parasite, has a complex life cycle involving two hosts: humans (the secondary host) and the female Anopheles mosquito (the primary host). The life cycle includes three main phases: schizogony, gamogony, and sporogony. The cycle begins when an infected female Anopheles mosquito bites a human and injects sporozoites into the bloodstream through its saliva. These sporozoites quickly travel to the liver cells. Inside the liver, they undergo asexual reproduction called schizogony, forming many merozoites. After being released from the liver cells, these merozoites then infect red blood cells (RBCs). Inside the RBCs, merozoites develop into unicellular trophozoites. The trophozoite grows, forms a central vacuole, and its nucleus divides to produce a schizont. This large schizont contains yellowish-brown pigmented granules called Schuffner's granules. The schizont then divides into numerous mononucleated merozoites. Eventually, the infected RBCs burst, releasing merozoites and a toxic substance called haemozoin into the bloodstream. This release triggers cycles of fever, chills, and other malaria symptoms, typically every 48 to 72 hours, depending on the Plasmodium species. The rapid destruction of red blood cells contributes significantly to the disease's severity. Some merozoites in the blood differentiate into male and female gametocytes. When an uninfected female Anopheles mosquito bites an infected human, it ingests these gametocytes along with the blood. Inside the mosquito's gut, the gametocytes mature, and male and female gametes fuse (fertilization) to form a diploid zygote. This zygote develops into an ookinete, which then migrates to the mosquito's gut wall and forms an oocyst. The oocyst undergoes meiosis and sporogony, producing many sporozoites. These sporozoites then migrate to the mosquito's salivary glands. The cycle is complete, and the mosquito can now infect another human when it bites. Malaria causes pathological changes not only in RBCs but also in the spleen and other internal organs. The incubation period is typically about 12 days. Early symptoms include headache, nausea, and muscle pain, followed by classic symptoms of shivering chills and high fever, which are linked to the synchronized release of merozoites and toxins into the blood. This entire cycle explains why malaria is a recurrent and debilitating disease.

In simple words: The Plasmodium parasite that causes malaria lives in both mosquitoes and humans. It moves from mosquito to human as sporozoites, grows in the liver, then infects red blood cells and multiplies. Some forms go back into mosquitoes, where they reproduce sexually.

🎯 Exam Tip: Focus on distinguishing between the asexual cycle in humans (liver and blood stages) and the sexual cycle in mosquitoes, and remember the key forms of the parasite (sporozoites, merozoites, gametocytes).

 

Question 78. Give an account of helminthic disease.
Answer: Helminthic diseases are caused by parasitic worms, or helminths, which commonly live as endoparasites within the human gut and blood. These diseases, collectively known as helminthiasis, can significantly impact health. Two common examples are Ascariasis and Filariasis. Ascariasis is caused by Ascaris lumbricoides, often called roundworms. It's a monogenic parasite, meaning it completes its life cycle in a single host (humans) and shows sexual dimorphism. Transmission occurs through ingesting embryonated eggs found in contaminated food and water. Children, especially those playing in contaminated soil, are at high risk of transferring eggs from hand to mouth. Symptoms include abdominal pain, vomiting, headaches, anemia, irritability, and diarrhea. Severe infections can lead to nutritional deficiencies, intense abdominal pain, and stunted growth. It can also cause enteritis (inflammation of the intestine), hepatitis (liver inflammation), and bronchitis (lung inflammation). Filariasis, also known as elephantiasis, is caused by Wuchereria bancrofti, a filarial worm. This worm lives in the lymph vessels and lymph nodes of humans. Wuchereria bancrofti is sexually dimorphic, viviparous (gives birth to live young), and digenic, meaning its life cycle involves two hosts: humans and the female Culex mosquito. The mosquito acts as a vector, transmitting microfilariae larvae. These larvae develop into adults in the human lymph glands. The accumulation of these worms obstructs the lymphatic system, leading to inflammation of the lymph nodes and severe swelling of body parts like the limbs, scrotum, and mammary glands, hence the name "elephantiasis." These diseases highlight the importance of proper hygiene and vector control for prevention.
In simple words: Helminthic diseases are caused by parasitic worms that live inside the human body. Examples include Ascariasis (roundworms, spread by dirty food/water) and Filariasis (filarial worms, spread by mosquitoes, causing swelling).

🎯 Exam Tip: When describing helminthic diseases, always mention the causative agent, mode of transmission, and characteristic symptoms, particularly for specific examples like Ascariasis and Filariasis.

 

Question 79. Tabulate the various types of innate immunity and their action mechanism.
Answer: Innate immunity is the body's natural, non-specific defense system that provides immediate protection against pathogens. It includes several types of barriers and mechanisms:

These combined mechanisms provide the first line of defense against a wide range of potential threats.
In simple words: Innate immunity is our body's first defense. It uses physical barriers (skin), chemical defenses (stomach acid), special cells that eat germs, and inflammation to stop infections quickly and generally.

🎯 Exam Tip: When tabulating types of immunity, ensure a clear distinction between barrier types (physical, physiological) and cellular mechanisms (phagocytosis, inflammation), providing a brief example for each.

 

Question 80. Point out the differences between active and passive immunity.
Answer: Active and passive immunity are two ways our body gains protection against diseases, but they differ significantly in how that protection is acquired and sustained. **Active Immunity:** 1. Active immunity is produced by the host's own immune system, meaning the body actively participates in creating the defense. 2. It develops when the body comes into contact with a pathogen (infection) or its antigen (like through a vaccine). 3. This type of immunity is durable and provides long-lasting, effective protection. 4. Immunological memory is present, allowing for a faster and stronger response upon re-exposure. 5. A booster effect is possible on subsequent doses of a vaccine or re-exposure to the antigen. 6. Immunity becomes effective only after a certain period, as the immune system needs time to develop a response. Our body learns to fight specific threats through active immunity. **Passive Immunity:** 1. Passive immunity is received passively; the host's immune system does not actively participate in its production. 2. It is acquired through antibodies obtained from an outside source, not made by the individual. 3. This immunity is transient (short-lived) and generally less effective for long-term protection. 4. No immunological memory is developed. 5. Subsequent doses are less effective, as the body does not "learn" from the exposure. 6. Immunity develops immediately upon receiving the antibodies. This offers quick, but temporary, protection.
In simple words: Active immunity is when your body learns to fight a disease itself, like after an infection or vaccine. It lasts a long time. Passive immunity is when you get antibodies from somewhere else, like a mother to her baby. It works fast but doesn't last long.

🎯 Exam Tip: Clearly define the source of antibodies (self-produced vs. external) and the presence or absence of immunological memory to distinguish between active and passive immunity.

 

Question 81. How primary immune response differ from secondary immune response?
Answer: The body's immune system responds differently to the first exposure to an antigen compared to subsequent exposures. This difference is categorized as primary and secondary immune responses:

The secondary response is much stronger and faster due to the presence of memory cells formed during the primary response, providing more effective protection.
In simple words: The primary response is slow when your body first meets a germ. The secondary response is fast and strong because your body remembers the germ from before.

🎯 Exam Tip: Emphasize the role of immunological memory in the secondary response, as it explains the faster onset, higher magnitude, and longer duration of antibody production.

 

Question 82. Explain the structure and role of thymus in primary lymphoid organ.
Answer: The thymus is a crucial primary lymphoid organ, most active during our early years, particularly neonatal and pre-adolescent periods. It's a flat, bilobed organ located behind the breastbone (sternum) and above the heart. Each of its two lobes contains numerous smaller sections called lobules, separated by connective tissue walls (septa). Each lobule is further divided into an outer cortex and an inner medulla. Within these lobules, developing T cells, called thymocytes, are arranged. Immature thymocytes are found in the outer cortex, while mature thymocytes are in the inner medulla. The thymus produces a hormone called thymosin, which is vital for the maturation and immunocompetence of T cells. This means thymosin helps T cells learn to recognize and fight specific pathogens. By early teenage years, the thymus often begins to shrink (atrophy) and is gradually replaced by fatty tissue, as most T cell education has already occurred. The thymus plays a central role in adaptive immunity by producing mature T lymphocytes.
In simple words: The thymus is a gland behind your chest that helps your T-cells grow and learn to fight infections, especially when you are young. It has two main parts inside, the cortex and medulla, where T-cells mature.

🎯 Exam Tip: Highlight that the thymus is a primary lymphoid organ because it's where lymphocytes (T cells) mature and become immunocompetent, not just where they are stored or activated.

 

Question 83. Describe the structure of lymph node with a labelled diagram.
Answer: A lymph node is a small, bean-shaped organ that is part of the lymphatic system, playing a critical role in filtering lymph and immune surveillance. It has three main zones: the cortex, paracortex, and medulla. The outermost layer is the **cortex**, primarily composed of B-lymphocytes, macrophages, and follicular dendritic cells. This is where B cells are typically activated and proliferate. Beneath the cortex lies the **paracortex** zone, which is rich in T lymphocytes and interdigitating dendritic cells. T cells in this region are activated by antigens presented by dendritic cells. The innermost zone is the **medulla**, consisting of medullary cords containing plasma cells and macrophages, separated by medullary sinuses. Lymph flows through these sinuses, allowing immune cells to interact with antigens. As lymph enters a node through afferent lymphatic vessels, it slowly filters through these regions. This process provides ample opportunity for phagocytic cells and dendritic cells to trap antigens. The lymph leaving the node through efferent lymphatic vessels carries antibodies secreted by activated plasma cells. Swelling of lymph nodes often indicates an active immune response to an infection. Lymph nodes are like filtering stations that ensure pathogens are identified and attacked by the immune system.
In simple words: A lymph node is a small bean-shaped filter for lymph. It has outer (cortex), middle (paracortex), and inner (medulla) parts where immune cells like B and T lymphocytes work to find and fight germs.

🎯 Exam Tip: When drawing and labeling a lymph node, clearly indicate the afferent and efferent lymphatic vessels, and the three main cortical and medullary regions with their primary cell types.

 

Question 84. Explain the types of cells involved in immune system.
Answer: The immune system relies on various specialized cells to protect the body from pathogens and diseases. These cells work together in a coordinated manner. **1. Lymphocytes:** These are a type of white blood cell, making up about 20-30% of them. Lymphocytes have a large nucleus and a small amount of cytoplasm. The two main types are B lymphocytes (B cells) and T lymphocytes (T cells).

• **B cells:** These mature in the bone marrow. When activated by an antigen, they divide rapidly to produce plasma cells, which secrete large amounts of antibodies. Some B cells also become memory cells, responsible for the secondary immune response.
• **T cells:** These mature in the thymus gland. They do not produce antibodies but recognize and destroy antigen-presenting cells. Key types include:
  • **Helper T cells:** Release chemical signals called cytokines that activate B cells and other immune cells.
  • **Killer T cells (Cytotoxic T lymphocytes):** Directly destroy infected or damaged cells and cancer cells.

**2. Macrophages:** These are large phagocytic cells that originate from monocytes. They engulf and digest foreign particles, pathogens, and cellular debris. Macrophages are crucial antigen-presenting cells, meaning they process antigens and display them to T cells to initiate an adaptive immune response. They act as the "clean-up crew" of the immune system. **3. Neutrophils:** These are the most abundant type of white blood cell and are among the first immune cells to arrive at a site of infection. Neutrophils are phagocytic and engulf bacteria and fungi. They have a short lifespan and are a key component of the innate immune response. **4. Dendritic Cells:** Dendritic cells are named for their long, thin membrane extensions that resemble the dendrites of nerve cells. They are excellent antigen-presenting cells, found in tissues that are in contact with the external environment, such as the skin (Langerhans cells), mucous membranes, and lymphoid organs. They capture antigens and present them to T-helper cells, linking the innate and adaptive immune responses. They initiate a robust immune response. The four types are Langerhans cells, interstitial cells, myeloid cells, and lymphoid cells. These diverse cell types ensure a comprehensive defense against a wide array of threats.
In simple words: The immune system uses many cells. Lymphocytes (B and T cells) specifically remember and fight germs. Macrophages eat germs and dead cells. Neutrophils are first responders that also eat germs. Dendritic cells show germs to other immune cells to start a strong defense.

🎯 Exam Tip: When explaining immune cells, categorize them by their main function (e.g., phagocytosis, antibody production, antigen presentation) and mention their origin and key roles in both innate and adaptive immunity.

 

Question 85. Write in detail about various types of antigen-antibody reactions.
Answer: Antigen-antibody reactions are fundamental processes in the immune system, where specific antibodies bind to their target antigens to neutralize or eliminate pathogens. These reactions can manifest in several ways: **1. Precipitin Reaction (Precipitation):** This reaction occurs when soluble antigens (antigens dissolved in fluid) combine with antibodies, forming large, insoluble complexes that visibly precipitate out of the solution. The antibodies involved in forming these precipitates are called precipitins. This mechanism is often used in laboratory tests to detect the presence of specific antigens or antibodies in a sample. The formation of these complexes renders the soluble antigens ineffective. **2. Agglutination Reaction (Agglutination):** Agglutination happens when antibodies bind to particulate antigens (like bacteria, red blood cells, or tiny latex beads with antigens attached). This binding causes the antigens to clump together, forming visible aggregates. The antibody responsible for this clumping is called an agglutinin. This reaction is widely used in blood typing to identify blood group antigens and in diagnosing certain infectious diseases. The clumping makes it easier for phagocytic cells to engulf and clear the pathogens. **3. Opsonisation:** Opsonisation is a process where pathogens are marked for destruction by phagocytes. Antibodies (called opsonins) bind to the surface of a pathogen and then to receptors on phagocytic cells. This binding acts like a "handle," making it much easier for the phagocyte to engulf and digest the pathogen. Opsonisation significantly enhances the efficiency of phagocytosis, as it essentially "tags" the pathogen for removal by immune cells. This process is crucial for clearing bacterial infections. **4. Neutralization:** Neutralization reactions involve antibodies binding directly to toxins (exotoxins) produced by bacteria or to the surface proteins of viruses. By binding to these active sites, the antibodies prevent the toxins from harming cells or stop viruses from attaching to and infecting host cells. The antibodies involved in neutralizing toxins are known as antitoxins. This mechanism is critical for protecting the body from the damaging effects of bacterial toxins and preventing viral infections by blocking their entry into cells. These diverse antigen-antibody interactions are essential for the body's protective immune responses, working together to combat various infectious agents.
In simple words: Antigen-antibody reactions are how our body fights germs. Antibodies can make dissolved germs clump up (precipitation), make whole germs stick together (agglutination), mark germs for immune cells to eat (opsonization), or block germs and toxins from doing harm (neutralization).

🎯 Exam Tip: For each type of antigen-antibody reaction, remember whether it involves soluble or particulate antigens and how the antibody's action leads to the elimination or inactivation of the antigen.

 

Question 86. Describe the structure of HIV with a diagram.
Answer: The Human Immunodeficiency Virus (HIV) belongs to the genus Lentivirus and is responsible for AIDS. When viewed under an electron microscope, HIV appears as a spherical virus, roughly 100-120 nanometers in diameter. Its structure is quite complex, designed for infecting human cells. At its core, HIV contains genetic material: two identical large single-stranded RNA molecules. Each RNA molecule is associated with several enzymes, including reverse transcriptase, protease, and ribonuclease, which are crucial for the virus's replication cycle. This core is surrounded by a protein layer called the **capsid protein**, forming a dense conical core. The capsid is enclosed by another protein layer known as the **matrix protein**. The outermost part of the virus is a **lipid bilayer envelope**, which is derived from the host cell membrane when the virus buds off. Embedded within this lipid envelope are two types of glycoprotein spikes: **gp41** (transmembrane glycoprotein) and **gp120** (outer glycoprotein). These spikes are crucial for the virus to attach to and enter human host cells, particularly CD4+ T cells. The presence of reverse transcriptase is unique to retroviruses like HIV, allowing them to convert their RNA genome into DNA within the host cell.
In simple words: HIV is a round virus with an outer skin (envelope) that has spikes. Inside, it has two strands of genetic material (RNA) and special enzymes like reverse transcriptase, all protected by protein layers.

🎯 Exam Tip: When describing the HIV structure, highlight the key components: the RNA genome, reverse transcriptase, capsid, matrix protein, and the glycoprotein spikes (gp120/gp41) on the envelope, as these are critical for its function and pathogenicity.

 

Question 87. Suggest some of the ways to prevent drug and alcohol abuse.
Answer: Preventing drug and alcohol abuse requires a multi-faceted approach, focusing on education, strong support systems, and professional help. Here are some key ways:

1. **Effectively dealing with peer pressure:** Many young people start using drugs due to pressure from friends. It is important to cultivate a supportive peer group and develop skills to resist negative influences. Learning to say "no" and choosing friends who share positive values can make a big difference.
2. **Seeking help from parents and peers:** Open communication with parents and trusted friends is vital. If someone is struggling, they should seek immediate help from family members or support groups. Talking about feelings of anxiety, guilt, or problems can prevent them from turning to substance abuse.
3. **Education and counseling:** Comprehensive education about the dangers of drugs and alcohol, combined with counseling, can help individuals develop positive attitudes. It also teaches coping mechanisms for dealing with life's problems and disappointments without resorting to substance use.
4. **Looking for danger signs:** Parents, teachers, and caregivers should be aware of the early signs that might indicate a tendency towards addiction. Recognizing these signs early allows for timely intervention and support.
5. **Seeking professional and medical assistance:** For those already struggling with abuse, professional medical and psychological assistance is available. This includes highly qualified psychologists, psychiatrists, and de-addiction and rehabilitation programs designed to help individuals overcome their substance dependency.

These strategies work together to create a healthier environment and support individuals in making informed, positive choices.
In simple words: To prevent drug and alcohol abuse, learn to resist peer pressure, talk to parents or friends about problems, get educated on risks, watch for early warning signs, and seek professional help if needed.

🎯 Exam Tip: When suggesting ways to prevent substance abuse, ensure your points cover individual actions (e.g., peer pressure resistance) as well as community and professional support systems (e.g., education, counseling, rehabilitation).

 

Question 1. Identify the mismatched pair and give reason.
(a) Plague - Yersinia pestis
(b) Filariasis - Wuchereria bancrofti
(c) Dermatomycosis - Trypanosoma gambiense
(d) Common cold - Rhinovirus
Answer: (c) Dermatomycosis - Trypanosoma gambiense
In simple words: The pair "Dermatomycosis – Trypanosoma gambiense" is incorrect. Dermatomycosis is caused by a fungus, while Trypanosoma gambiense is a parasite that causes African sleeping sickness.

🎯 Exam Tip: For "mismatched pair" questions, identify the incorrect item and briefly state the correct information for both parts of the pair.

 

Question 2. In which form does the malarial parasite enter the human body through mosquito? What is the target site of the parasite immediately after entering the host body?
Answer: The malarial parasite enters the human body in the form of sporozoites when an infected mosquito bites. Once inside, these sporozoites quickly travel to and infect the liver cells first. The liver acts as their initial site of multiplication before they infect red blood cells.
In simple words: Malaria parasites enter the body as sporozoites from a mosquito bite. They first go to the liver cells in the human body.

🎯 Exam Tip: Remember the specific stage (sporozoite) and the first organ infected (liver) for the malarial parasite life cycle in humans.

 

Question 3. A boy of ten years had suffered from chicken-pox. His grandmother consoled him that he is not expected to have it for the rest of his life. Whether his grandmother is right? If so how it happens?
Answer: Yes, his grandmother is right. After a chickenpox infection, the body creates special defense cells called lymphocytes that "remember" the virus. It also produces antibodies to fight the infection. This immunological memory allows the immune system to quickly recognize and fight off the chickenpox virus if it tries to infect the body again, preventing the disease from occurring a second time.
In simple words: Yes, the grandmother is right. After getting chickenpox once, your body remembers the virus. So, if the virus tries to attack again, your body knows how to fight it off quickly, and you won't get sick again.

🎯 Exam Tip: Explain how the immune system develops "memory" (lymphocytes) and produces specific antibodies for long-term protection after the first exposure to a pathogen.