All questions of Human Health & Diseases for NEET Exam

IgG immunoglobin me sabse jyada 80% paye jate h . ye sbse chote imuno globin hote h kyuki enme paratopes kevel 2 hote h upr se ye monovalant hote h. chote size ke karan ye placenta ko cross kr jate h

Thymus gland is the correct option as it is large at the time of birth but reduces to a very small size in adults.

Explanation:

Thymus gland is a specialized gland of the lymphatic system that plays an important role in the development of the immune system. It is located in the upper thorax, behind the sternum, and in front of the heart. The thymus gland is large at the time of birth and continues to grow until puberty. After puberty, the thymus gland begins to shrink and is replaced by fatty tissue. By the age of 20, the thymus gland has reduced to about one-third of its maximum size, and by the age of 50, it has reduced to only a few grams of fatty tissue.

Why is Thymus gland large at the time of birth?

The thymus gland is very active during fetal development and plays a crucial role in the development of the immune system. The thymus gland produces T-lymphocytes, which are immune cells that play a crucial role in fighting infections and diseases. The thymus gland is essential for the development of T-lymphocytes, which are responsible for recognizing and attacking foreign substances in the body. The thymus gland is particularly important during fetal development because the fetus does not have a fully developed immune system and relies on the mother's immune system for protection.

Why does Thymus gland reduce in size in adults?

The thymus gland begins to shrink after puberty because the production of T-lymphocytes decreases with age. As a result, the thymus gland is no longer required to produce large numbers of T-lymphocytes, and its function gradually declines. The thymus gland is gradually replaced by fatty tissue, which is an irreversible process. However, the T-lymphocytes that are produced by the thymus gland during fetal development and childhood continue to circulate in the body and play a crucial role in the immune system throughout life.

Explanation:
Proto-oncogenes are normal genes in cells that regulate cell growth and division. However, if these genes are mutated or activated, they can become oncogenes, which promote uncontrolled cell growth and division, leading to the development of cancer. Several proto-oncogenes have been identified in normal cells, and when activated, they can turn into oncogenes, potentially leading to the transformation of the cells into cancer cells.

The correct sequence of words to complete the paragraph is "proto-oncogenes, oncogenes." The other options presented include "oncogenes, proto-oncogenes," "cellular oncogenes, proto-oncogenes," and "cellular oncogenes, oncogenes," but none of these accurately reflect the relationship between proto-oncogenes and oncogenes.

In summary, proto-oncogenes are normal genes that can become oncogenes if they are mutated or activated. Several proto-oncogenes have been identified in normal cells, and when activated, they can turn into oncogenes, which can lead to the development of cancer.

Incorrect Immune System Component and Role Match

Explanation:
The immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful pathogens. The immune system components and their respective roles are as follows:

a) Interferons - Secreted by virus-infected cells and protect non-infected cells from further viral infection. They stimulate the production of antiviral proteins that prevent the virus from replicating in healthy cells.

b) B-lymphocytes - Produce antibodies in response to pathogens into blood to fight with them. B-lymphocytes are a type of white blood cell that recognizes and neutralizes specific pathogens by producing antibodies that bind to and destroy them.

c) Macrophages - Mucus-secreting cells that trap microbes entering in the body. This is an incorrect match as macrophages are actually white blood cells that engulf and digest foreign substances, such as bacteria and viruses, in a process called phagocytosis.

d) IgA - Present in colostrum in early days of lactation to protect infant from diseases. IgA is an antibody that is found in secretions such as tears, saliva, and breast milk. It helps to prevent pathogens from entering the body through the mucous membranes.

In conclusion, the correct match of immune system components and their respective roles is important to understand the functioning of the immune system and to develop effective strategies to combat diseases.

Yellow fever and dengue are the pair of diseases that are viral and transmitted by mosquitoes.

Yellow Fever:
- Yellow fever is a viral disease caused by the yellow fever virus.
- It is primarily transmitted by the bite of infected female mosquitoes, especially the Aedes aegypti species.
- The virus is endemic in tropical regions of Africa and Central and South America.
- Symptoms of yellow fever include fever, headache, muscle pain, jaundice, and bleeding.
- In severe cases, it can lead to organ failure and death.
- There is no specific treatment for yellow fever, but a vaccine is available for prevention.

Dengue:
- Dengue is a viral disease caused by the dengue virus.
- It is transmitted by the bite of infected female Aedes mosquitoes, primarily Aedes aegypti.
- Dengue is common in tropical and subtropical regions around the world.
- Symptoms of dengue include high fever, severe headache, joint and muscle pain, rash, and mild bleeding.
- In severe cases, it can lead to dengue hemorrhagic fever or dengue shock syndrome, which can be life-threatening.
- There is no specific treatment for dengue, but supportive care can help manage symptoms.

Viral Diseases Transmitted by Mosquitoes:
- Mosquitoes are known to transmit several viral diseases, including yellow fever, dengue fever, Zika virus, chikungunya, and West Nile virus.
- These viruses are primarily transmitted when a mosquito bites an infected person and then bites another person, transmitting the virus through its saliva.
- Mosquito-borne viral diseases are more common in tropical and subtropical regions where mosquito populations are abundant.
- The Aedes mosquitoes, particularly Aedes aegypti, are the main vectors for these viral diseases.

Conclusion:
- Among the given options, the pair of diseases that are both viral and transmitted by mosquitoes is yellow fever and dengue. Both diseases are caused by different viruses and are primarily transmitted by the bite of infected Aedes mosquitoes.

lgE is the most abundant antibody produced against allergens

Allergens are substances that can trigger an allergic response in individuals who are sensitive or allergic to them. When allergens enter the body, they can bind to specific antibodies called immunoglobulin E (IgE) antibodies. IgE antibodies are produced by a type of white blood cell called B cells in response to exposure to allergens. These antibodies are particularly involved in allergic reactions.

Explanation:
There are five major classes of antibodies, also known as immunoglobulins (Ig): IgA, IgD, IgE, IgG, and IgM. Each class of antibody has its own unique structure and function. Among these, IgE is the most abundant antibody produced against allergens.

Key Points:
- IgE is produced in response to allergen exposure.
- It plays a crucial role in allergic reactions by binding to allergens and triggering the release of chemicals such as histamine from mast cells and basophils.
- Histamine release leads to the typical symptoms of an allergic reaction, such as itching, swelling, redness, and increased mucus production.
- IgE antibodies are involved in allergic diseases such as allergic rhinitis (hay fever), asthma, and atopic dermatitis (eczema).
- The production of IgE antibodies is tightly regulated to prevent unnecessary allergic reactions.
- Individuals with allergies often have higher levels of IgE antibodies in their blood compared to non-allergic individuals.

Conclusion:
In summary, IgE is the most abundant antibody produced against allergens. It plays a key role in allergic reactions by binding to allergens and triggering the release of chemicals that cause allergy symptoms. Understanding the role of IgE antibodies in allergic reactions is important for the development of diagnostic tests and targeted treatments for allergies.

Infectious and Non-infectious Diseases

Infectious diseases are those that are caused by pathogenic microorganisms such as bacteria, viruses, fungi, and parasites. These diseases can be transmitted from one person to another through various modes of transmission such as direct contact, droplets, airborne, fecal-oral route, and vector-borne.

Non-infectious diseases are those that are not caused by pathogenic microorganisms. These diseases may have genetic, environmental, or lifestyle factors as their causes. Some examples of non-infectious diseases include cancer, diabetes, hypertension, and heart disease.

Answer Explanation

The pair that contains an infectious and a non-infectious disease respectively is option 'B', which is AIDS and cancer.

- AIDS is an infectious disease caused by the human immunodeficiency virus (HIV). It is primarily transmitted through sexual contact, blood transfusions, and vertical transmission from mother to child during pregnancy, childbirth, or breastfeeding.
- Cancer, on the other hand, is a non-infectious disease that is caused by uncontrolled growth and division of abnormal cells in the body. It can be caused by genetic mutations, exposure to environmental factors such as tobacco smoke and ultraviolet radiation, and lifestyle factors such as poor diet and lack of physical activity.

Therefore, option 'B' is the correct answer as it contains one infectious disease (AIDS) and one non-infectious disease (cancer).

World AIDS Day is celebrated on 1st December every year. It is an opportunity for people worldwide to unite in the fight against HIV, show support for people living with HIV, and remember those who have died from HIV/AIDS-related illnesses. The day also aims to raise awareness about HIV/AIDS, reduce stigma, and encourage people to get tested and seek treatment.

The History of World AIDS Day
- World AIDS Day was first observed in 1988, making 2021 the 33rd anniversary of the event.
- The day was established by the World Health Organization (WHO) to raise awareness about the global AIDS epidemic and to encourage progress in HIV/AIDS prevention, treatment, and care.
- Since its inception, World AIDS Day has been recognized by governments, non-governmental organizations, and individuals around the world.

Why is World AIDS Day Important?
- HIV/AIDS remains one of the most significant public health challenges globally.
- Approximately 38 million people worldwide are living with HIV, and 690,000 people died from AIDS-related illnesses in 2019.
- Despite significant progress in HIV prevention, treatment, and care, many people still face barriers to accessing these services.
- World AIDS Day provides an opportunity to raise awareness about HIV/AIDS, reduce stigma, and encourage people to get tested and seek treatment.

How is World AIDS Day Celebrated?
- World AIDS Day is marked by events and activities worldwide, including candlelight vigils, marches, conferences, and awareness-raising campaigns.
- The theme for World AIDS Day 2021 is "End inequalities, end AIDS."
- The theme highlights the need to address social and economic inequalities that contribute to the HIV epidemic, such as poverty, discrimination, and gender inequality.
- The day also provides an opportunity to showcase progress in the global response to HIV/AIDS and to renew commitments to ending the epidemic.

In conclusion, World AIDS Day is an important global event that aims to raise awareness about HIV/AIDS, reduce stigma, and encourage people to get tested and seek treatment. By working together, we can end the HIV epidemic and ensure that everyone living with HIV has access to the care and support they need.

Disease and Pathogen Pairing

Typhoid - Salmonella typhi

Explanation:

Typhoid is a bacterial infection that is caused by the bacterium Salmonella typhi. This bacterium is commonly found in contaminated food and water, especially in areas with poor sanitation. The symptoms of typhoid include fever, headache, abdominal pain, and diarrhea.

Pneumonia - Haemophilus pneumoniae

Explanation:

Pneumonia is a lung infection that can be caused by many different types of bacteria, viruses, and fungi. One of the common pathogens that cause pneumonia is Haemophilus pneumoniae. The symptoms of pneumonia include cough, fever, and difficulty breathing.

Malaria - Ascaris lumbricoides

Explanation:

Malaria is a parasitic disease that is transmitted by infected female Anopheles mosquitoes. The parasite responsible for malaria is Plasmodium falciparum, which infects red blood cells and causes fever, chills, and flu-like symptoms. Ascaris lumbricoides, on the other hand, is a type of roundworm that infects the intestines.

Ringworm - Entamoeba histolytica

Explanation:

Ringworm is a fungal infection of the skin that can affect different parts of the body, such as the scalp, feet, and groin. It is caused by a group of fungi called dermatophytes. Entamoeba histolytica, on the other hand, is a protozoan parasite that can cause amoebiasis, a disease that affects the intestines. It is not associated with ringworm.

Therefore, the correct pairing of a disease and its pathogen is Typhoid - Salmonella typhi.

Amoebic dysentery (amoebiasis) is caused by Entamoeba histolytica.

Amoebic dysentery, also known as amoebiasis, is a parasitic infection that affects the intestines. It is caused by the protozoan parasite Entamoeba histolytica. This parasite is commonly found in areas with poor sanitation and contaminated water. It can also be transmitted through the consumption of food or water contaminated with the cysts of the parasite.

Mode of Transmission:
The primary mode of transmission of Entamoeba histolytica is through the ingestion of contaminated food or water. The parasite exists in two forms: a cyst and a trophozoite. The cyst is the dormant stage of the parasite that can survive outside the body for a long time. When a person ingests the cyst, it passes through the stomach and reaches the intestines, where it transforms into the active trophozoite form. The trophozoites then multiply and invade the intestinal lining, causing inflammation and destruction.

Pathogenesis:
Once the trophozoites invade the intestinal lining, they can cause a range of symptoms ranging from mild diarrhea to severe dysentery. The trophozoites feed on the intestinal cells, causing ulceration and tissue destruction. They can also penetrate the intestinal wall and enter the bloodstream, leading to extra-intestinal manifestations such as liver abscesses.

Symptoms:
The symptoms of amoebic dysentery include:
- Diarrhea (often bloody)
- Abdominal pain and cramping
- Fatigue
- Weight loss
- Fever
- Nausea and vomiting

Diagnosis:
The diagnosis of amoebic dysentery involves the detection of the parasite in stool samples. Microscopic examination of the stool can reveal the presence of Entamoeba histolytica trophozoites or cysts. In some cases, a blood test may be performed to detect antibodies against the parasite.

Treatment and Prevention:
Amoebic dysentery can be treated with specific anti-parasitic medications that target Entamoeba histolytica. These medications can help eliminate the parasite from the intestines and alleviate the symptoms. It is also important to maintain good personal hygiene and avoid consuming food or water from unreliable sources to prevent the transmission of the infection.

In conclusion, amoebic dysentery is caused by the protozoan parasite Entamoeba histolytica. It is transmitted through the ingestion of contaminated food or water and can cause a range of gastrointestinal symptoms. Prompt diagnosis and treatment are essential to manage the infection effectively.

The correct answer is option 'B' - ganja and charas affect the cardiovascular system.

Ganja and charas, commonly known as marijuana or cannabis, are drugs derived from the Cannabis plant. These drugs have psychoactive properties and can cause various effects on the body, including those on the cardiovascular system.

Here is a detailed explanation of how ganja and charas affect the cardiovascular system:

1. Vasodilation:
- Both ganja and charas contain cannabinoids, primarily tetrahydrocannabinol (THC), which can cause vasodilation.
- Vasodilation refers to the widening of blood vessels, leading to an increase in their diameter.
- When blood vessels dilate, it reduces peripheral resistance and allows for increased blood flow.
- This effect can cause a decrease in blood pressure.

2. Tachycardia:
- Another effect of ganja and charas on the cardiovascular system is an increase in heart rate, known as tachycardia.
- THC activates the sympathetic nervous system, which increases the release of norepinephrine and epinephrine, leading to an increased heart rate.
- Tachycardia can put additional stress on the heart and may have adverse effects, especially in individuals with pre-existing cardiovascular conditions.

3. Increased risk of heart attack:
- The combination of vasodilation and tachycardia can increase the risk of a heart attack, particularly in susceptible individuals.
- When blood vessels dilate, it can lead to a decrease in coronary blood flow, which may be insufficient to meet the increased oxygen demand due to tachycardia.
- This can result in myocardial ischemia, where the heart muscle does not receive enough oxygen, potentially leading to a heart attack.

4. Blood clotting:
- Ganja and charas can also affect blood clotting.
- THC has been shown to inhibit platelet aggregation, which is the process of platelets clumping together to form a blood clot.
- This effect may increase the risk of bleeding in individuals taking anticoagulant medications or those with bleeding disorders.

In summary, ganja and charas affect the cardiovascular system primarily through vasodilation, tachycardia, increased risk of heart attack, and alterations in blood clotting. It is important to note that these effects may vary depending on the dosage, frequency of use, and individual susceptibility.

**Explanation:**

**Introduction:**
Antibiotics are medications that are used to treat bacterial infections. They work by killing or inhibiting the growth of bacteria. However, not all diseases are caused by bacteria, and therefore, not all diseases can be cured by antibiotics.

**Explanation:**
Out of the diseases listed in the options, amoebiasis is the one that cannot be cured by taking antibiotics. Here's why:

1. **Plague:** Plague is caused by the bacterium Yersinia pestis. It can be treated with antibiotics such as streptomycin, gentamicin, or doxycycline. With prompt treatment, most people recover from the plague.

2. **Amoebiasis:** Amoebiasis is caused by the parasite Entamoeba histolytica. Antibiotics are not effective against parasites. The treatment for amoebiasis typically involves antiparasitic medications like metronidazole or tinidazole, which specifically target the parasite.

3. **Leprosy:** Leprosy is caused by the bacterium Mycobacterium leprae. It is treated with a combination of antibiotics such as dapsone, rifampicin, and clofazimine. Leprosy treatment usually requires long-term antibiotic therapy to completely eliminate the bacteria.

4. **Whooping cough:** Whooping cough, or pertussis, is caused by the bacterium Bordetella pertussis. Antibiotics such as azithromycin or erythromycin can be used to treat whooping cough, especially in the early stages of the infection.

Therefore, the correct answer is **(b) Amoebiasis**, as it is caused by a parasite and requires antiparasitic medications rather than antibiotics for treatment.

Marijuana Extraction

Marijuana, also known as cannabis, is a psychoactive drug that is derived from the Cannabis plant. It is primarily extracted from the dried leaves and flowers of the herb. Let's explore this in more detail:

1. Cannabis Plant
- Cannabis is a flowering plant that belongs to the Cannabaceae family.
- It has three primary species: Cannabis sativa, Cannabis indica, and Cannabis ruderalis.

2. Marijuana Extraction Process
- Marijuana extraction involves separating the desired compounds, such as cannabinoids and terpenes, from the plant material.
- The most common method of extraction is through the use of solvents like ethanol, butane, or CO2.
- The dried leaves and flowers of the cannabis plant contain the highest concentration of these desired compounds.

3. Dried Leaves and Flowers
- The leaves and flowers of the cannabis plant are rich in cannabinoids, including tetrahydrocannabinol (THC) and cannabidiol (CBD).
- THC is the primary psychoactive compound responsible for the "high" experienced when consuming marijuana.
- CBD, on the other hand, is non-psychoactive and has various potential therapeutic benefits.

4. Other Plant Parts
- While the leaves and flowers are the main sources of marijuana, other parts of the cannabis plant can also contain cannabinoids, although in lower concentrations.
- For example, the stems and seeds may contain some cannabinoids, but they are less potent compared to the leaves and flowers.

Conclusion
In conclusion, marijuana is primarily extracted from the dried leaves and flowers of the cannabis plant. These plant parts contain the highest concentration of cannabinoids, including THC and CBD. The extraction process involves separating these desired compounds from the plant material using solvents. While other parts of the plant, such as stems and seeds, may also contain cannabinoids, they are not commonly used for marijuana extraction due to their lower potency.

The correct answer is option 'C' (i), (iii) and (iv) - infections, lifestyle, and genetic disorders all affect human health.

(i) Infections: Infections are caused by various microorganisms such as bacteria, viruses, fungi, and parasites. These microorganisms can enter the body through various routes and cause diseases. Infections can range from mild illnesses such as the common cold to more severe diseases like pneumonia, tuberculosis, or HIV/AIDS. Infections can significantly impact human health by causing symptoms, weakening the immune system, and potentially leading to complications or even death.

(iii) Lifestyle: Lifestyle choices play a crucial role in determining an individual's health. Unhealthy lifestyle habits such as a sedentary lifestyle, poor diet, smoking, excessive alcohol consumption, and drug abuse can have detrimental effects on human health. These habits can increase the risk of developing chronic diseases like obesity, cardiovascular diseases, diabetes, and certain types of cancers. On the other hand, adopting a healthy lifestyle that includes regular exercise, balanced nutrition, adequate sleep, and stress management can promote overall well-being and reduce the risk of various diseases.

(iv) Genetic disorders: Genetic disorders are caused by abnormalities or mutations in an individual's genes. These disorders can be inherited from one or both parents or can occur as a result of spontaneous genetic mutations. Genetic disorders can affect various aspects of human health, including physical and mental development, metabolism, immune system function, and susceptibility to certain diseases. Examples of genetic disorders include Down syndrome, cystic fibrosis, sickle cell anemia, and Huntington's disease. These disorders can have varying degrees of severity and can significantly impact an individual's quality of life and overall health.

In conclusion, infections, lifestyle choices, and genetic disorders are all factors that can affect human health. Understanding these factors and taking appropriate measures to prevent infections, adopt a healthy lifestyle, and manage genetic disorders can help promote better health outcomes.

Understanding Sertoli Cells
Sertoli cells, located in the seminiferous tubules of the testes, play essential roles in male reproductive physiology. They are often referred to as "nurse cells" because they provide support and nourishment to developing sperm cells.
Functions of Sertoli Cells
- Provide Nutrition to Spermatogonia: Sertoli cells supply nutrients and biochemical support to spermatogonia and developing spermatozoa, facilitating their growth and maturation.
- Support Developing Germ Cells: They create a protective environment for germ cells, ensuring proper development and differentiation into mature sperm.
- Secrete Androgen-Binding Protein (ABP): Sertoli cells produce ABP, which binds testosterone and keeps its levels high in the seminiferous tubules, promoting spermatogenesis.
Why Option B is Correct
- Secretion of Testosterone: Sertoli cells do not secrete testosterone. This function is primarily performed by Leydig cells, which are located in the interstitial space of the testes. Leydig cells respond to luteinizing hormone (LH) and are responsible for the production of testosterone, which is crucial for male secondary sexual characteristics and overall reproductive health.
Conclusion
In summary, while Sertoli cells have vital supportive and regulatory roles in spermatogenesis, they are not involved in the secretion of testosterone. This vital function is attributed to Leydig cells, making option B the correct choice in this context.

Innate immunity is the first line of defense of our body against pathogens. It consists of physiological and cellular barriers that prevent the entry and growth of microorganisms in our body. These barriers are present in different parts of our body and work together to protect us from infections.

Physiological barriers:

Physiological barriers are the physical and chemical barriers present in our body that prevent the entry and growth of microorganisms. The following statements regarding different physiological barriers of innate immunity are correct:

a) Acid present in the stomach, saliva in the mouth, tears from the eyes prevent the growth of microorganisms and constitute physiological barriers of our body.
- Acid in the stomach kills most of the microorganisms that enter our body through food or water.
- Saliva in the mouth contains enzymes and antibodies that prevent the growth of microorganisms in the oral cavity.
- Tears from the eyes contain lysozyme, an enzyme that can break down the cell wall of bacteria and prevent their growth.

b) Mucous membrane lining the respiratory, gastrointestinal and urinogenital tracts helps in trapping the microbes and constitute physiological barriers of our body.
- This statement is not correct as the mucous membrane is not just a physical barrier but also a site of active immune defense. The mucous membrane contains specialized cells called epithelial cells that secrete mucus, which traps microorganisms and prevents their entry into the body. The mucous membrane also contains immune cells such as macrophages, dendritic cells, and lymphocytes that can recognize and destroy the invading microorganisms.

Cellular barriers:

Cellular barriers are the immune cells present in our body that can recognize and destroy the invading microorganisms. The following statements regarding different cellular barriers of innate immunity are correct:

c) Certain types of leucocytes such as polymorphonuclear leucocytes (PMNL-neutrophils) and lymphocytes such as natural killer cells, constitute cellular barriers of our body.
- Polymorphonuclear leucocytes (PMNL-neutrophils) are the most abundant type of white blood cells in our body. They can recognize and engulf bacteria and other microorganisms.
- Natural killer cells are a type of lymphocyte that can recognize and kill virus-infected and cancerous cells.

d) Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection and constitute cytokine barriers of our body.
- This statement is correct. Interferons are proteins produced by virus-infected cells that activate the immune cells and protect non-infected cells from viral infection. Interferons can induce the expression of antiviral genes in the non-infected cells, which can prevent the replication of the virus.

In conclusion, statement b is not correct as the mucous membrane is not just a physical barrier but also a site of active immune defense.

Allergy and Mast Cells

Allergy is an exaggerated immune response to harmless substances called allergens. These allergens can be anything from pollen to certain foods, medications, or animal dander. During an allergic response, mast cells play an active role in the inflammatory process.

Mast Cells

Mast cells are a type of white blood cell that resides in connective tissues throughout the body, particularly in areas that are exposed to the external environment such as the skin, respiratory tract, and gastrointestinal tract. They are involved in both innate and adaptive immunity.

Role of Mast Cells in Allergy

When an allergen enters the body of an allergic individual, it triggers an immune response. In the case of allergies, the immune system reacts to the allergen as if it were harmful. Mast cells have specific receptors on their surface that recognize and bind to allergens.

Release of Mediators

Upon allergen binding, mast cells release a variety of chemical mediators, including histamine, leukotrienes, and prostaglandins. These mediators are responsible for the symptoms of allergies such as itching, redness, swelling, and increased mucus production.

Effects on Surrounding Tissues

Histamine, one of the primary mediators released by mast cells, causes blood vessels to dilate and become more permeable. This leads to increased blood flow to the affected area and the leakage of fluid and immune cells into the surrounding tissues. The resulting inflammation contributes to the characteristic symptoms of allergies.

Recruitment of Other Immune Cells

Mast cells also play a role in recruiting other immune cells to the site of the allergic reaction. They release chemotactic factors that attract eosinophils, basophils, and T-cells to the area. These immune cells further contribute to the inflammatory response.

Conclusion

In summary, mast cells actively participate during allergies by recognizing and binding to allergens, releasing chemical mediators that cause inflammation and allergic symptoms, and recruiting other immune cells to the site of the allergic reaction. Therefore, the correct answer to the question is option 'C' - Mast cells.

Cancer is a dreadful disease and is also called a malignant neoplasm or the disease of uncontrolled proliferation of certain cells without differentiation. The term neoplasm is also used as a synonym for tumour. The cells of tumour cells can pass to new sites for forming a secondary tumour, in a process called metastasis. The following are the properties of cancer cells :

1. They do not need external extracellular growth factors.
2. They do not have control over the cell cycle.
3. They divide rapidly and form a solid mass of cells.
4. They do not exhibit the property of contact inhibition.
5. The nuclei of these cells are irregular, and granular.
6. They do not differentiate and keep dividing continuously.
7. There is no definite life span for a cancer cell.

Hope it helps you.... :)

Typhoid fever in human being is caused by Salmonella typhi (bacteria).
Small intestine is infected.
Symptom--- high fever, weakness, stomach pain, constipation, headache, loss of appetite.
Confirmed by Widal Test.

Introduction:
Cocaine is a powerful stimulant drug that is derived from the coca plant. It has been used for centuries as a recreational drug due to its euphoric effects. Commonly referred to as "coke" or "crack," cocaine is known for its addictive nature and harmful health effects.

Common Names:
Cocaine is commonly called as:
- Smack: This term is incorrect as smack refers to heroin, which is a different drug altogether. Therefore, option 'a' is incorrect.
- Coke: This is a widely used term to refer to cocaine. It is derived from the drug's full name and is commonly used in informal conversations. Therefore, option 'b' is correct.
- Crack: Crack cocaine is a form of cocaine that has been processed into a solid crystal. It is typically smoked and produces an intense but short-lived high. Crack cocaine is commonly referred to as just "crack." Therefore, option 'c' is correct.

Correct Answer:
The correct answer is option 'D' - both (b) and (c). This is because cocaine is commonly called both "coke" and "crack."

Explanation:
- Cocaine is a drug that is known by different names depending on its form and method of use.
- The term "coke" is often used to refer to powdered cocaine, which is typically snorted.
- On the other hand, "crack" is the term used for cocaine that has been processed into a solid crystal and is smoked.
- Both "coke" and "crack" are widely recognized and used terms to refer to cocaine in different forms.
- It is important to note that these terms are used informally and may vary in different regions or social contexts.

Conclusion:
Cocaine is a highly addictive and dangerous drug that is known by various names. It is commonly referred to as "coke" when in powdered form and "crack" when processed into a solid crystal. These terms are used informally and may vary in different regions. It is crucial to understand the risks and harmful effects associated with cocaine use, regardless of the name it is called.

Plasmodium is a protozoan parasite that causes malaria in humans. The life cycle of Plasmodium involves both asexual and sexual reproduction. The asexual reproduction takes place in the human host, while the sexual reproduction takes place in the female Anopheles mosquito.

Explanation:
The life cycle of Plasmodium involves the following stages:

1. Sporozoites: The sporozoites are the infective form of Plasmodium, which are injected into the human host by the female Anopheles mosquito while taking a blood meal.

2. Liver stage: The sporozoites enter the liver cells and multiply asexually to form merozoites.

3. Blood stage: The merozoites are released into the bloodstream and infect the red blood cells, where they multiply asexually and cause the symptoms of malaria.

4. Gametocytes: Some of the merozoites differentiate into male and female gametocytes, which are the sexual forms of Plasmodium.

5. Mosquito stage: When a female Anopheles mosquito bites an infected human, it ingests the gametocytes along with the blood.

6. Fertilization: The male gametocytes fertilize the female gametocytes in the mosquito's gut, forming zygotes.

7. Ookinete: The zygotes develop into motile ookinetes, which penetrate the gut wall and form oocysts.

8. Sporozoites: The oocysts release sporozoites into the mosquito's hemocoel, which migrate to the salivary glands.

9. Transmission: When the infected mosquito bites a human, it injects the sporozoites into the bloodstream, and the cycle repeats.

Therefore, the sexual reproduction of Plasmodium takes place in the female Anopheles mosquito, while the asexual reproduction takes place in the human host. Hence, the correct answer is option B.

Where will you look for the sporozoites of malarial parasite?

To find the sporozoites of the malarial parasite, we need to understand the life cycle of the parasite and its transmission to humans. Malaria is caused by the Plasmodium parasite and is primarily transmitted through the bite of an infected female Anopheles mosquito. Let's examine the options given and explain why the correct answer is option 'A' - saliva of infected female Anopheles mosquito.

a) Saliva of infected female Anopheles mosquito
- When an infected female Anopheles mosquito bites a human, it injects saliva into the human's bloodstream to prevent blood clotting. Along with saliva, it also injects sporozoites, which are the infective form of the malarial parasite.
- These sporozoites travel through the bloodstream and eventually reach the liver, where they invade liver cells and undergo asexual replication.
- From the liver, they are released back into the bloodstream as merozoites, which invade and multiply within red blood cells, causing symptoms of malaria.

b) Salivary glands of freshly molted female Anopheles mosquito
- This option is incorrect because the sporozoites are not found in the salivary glands of freshly molted female Anopheles mosquitoes. It is only when the mosquito becomes infected by feeding on an infected human that the sporozoites develop and reach the salivary glands.

c) Spleen of infected humans
- The spleen plays a role in the immune response against malaria, but it is not the site where sporozoites are found. Sporozoites are injected into the bloodstream by infected mosquitoes and primarily invade liver cells, not the spleen.

d) Red blood corpuscles of humans suffering from malaria
- While red blood cells are indeed the target of the malarial parasite during the blood stage of infection, sporozoites are not found within red blood cells. Sporozoites are injected into the bloodstream by infected mosquitoes and initially invade liver cells, not red blood cells.

In conclusion, the correct answer is option 'A' - the sporozoites of the malarial parasite are found in the saliva of infected female Anopheles mosquitoes. When these infected mosquitoes bite humans, they inject sporozoites along with saliva into the bloodstream, initiating the infection process.

Pneumonia is a respiratory infection that can be caused by various pathogens, including bacteria, viruses, and fungi. It is primarily transmitted through respiratory droplets, which are released when an infected person coughs or sneezes. These droplets contain the infectious agents, and if a healthy person inhales them, they can become infected with pneumonia.

Pathogens causing pneumonia:
- Streptococcus pneumoniae: This bacterium is one of the most common causes of pneumonia. It can also cause other respiratory infections such as sinusitis and ear infections.
- Haemophilus influenzae: This bacterium is another common cause of pneumonia, especially in young children and individuals with weakened immune systems.

Transmission of pneumonia:
- Inhaling droplets: When an infected person coughs or sneezes, they release respiratory droplets into the air. If a healthy person inhales these droplets, they can become infected with pneumonia.
- Sharing utensils: It is possible to transmit pneumonia by sharing utensils with an infected person, as the pathogens can be present on the utensils and can be transferred to a healthy person.

Vaccine for pneumonia:
- Incorrect statement: The statement that there is no vaccine available to prevent pneumonia is incorrect. Vaccines are available for certain pathogens that cause pneumonia, including Streptococcus pneumoniae and Haemophilus influenzae. These vaccines can help prevent pneumonia caused by these specific pathogens.

Conclusion:
The incorrect statement is option C, which states that there is no vaccine available to prevent pneumonia. In reality, vaccines are available for some of the common pathogens that cause pneumonia, such as Streptococcus pneumoniae and Haemophilus influenzae. These vaccines play a crucial role in preventing pneumonia and reducing its burden on public health.

Incorrect Statements about Malignant Tumors and Sarcoma

Incorrect Statement 1: Malignant tumors normally remain confined to their original location, do not spread to other body parts and cause less damage.
Explanation: Malignant tumors are cancerous growths that can invade nearby tissues and spread to other parts of the body through the bloodstream or lymphatic system. They are harmful and can cause significant damage to the affected organs and tissues.

Incorrect Statement 2: Cancer arising from epithelial tissues of internal organs and glands is referred to as sarcoma e.g., breast cancer, cervical cancer, etc.
Explanation: Sarcoma is a type of cancer that arises from the connective tissue such as bone, cartilage, muscle, and fat. Cancer arising from epithelial tissues of internal organs and glands is referred to as carcinoma, not sarcoma. Examples of carcinoma include breast cancer, cervical cancer, lung cancer, etc.

Correct Answer: D) Both statements 1 and 2 are incorrect.

In summary, malignant tumors are cancerous and can spread to other parts of the body, causing significant damage. Sarcoma is a type of cancer that arises from connective tissue, while carcinoma is a type of cancer that arises from epithelial tissues of internal organs and glands.

Humoral immunity is associated with B-cells.

Introduction:
The immune system is responsible for defending the body against external pathogens such as bacteria, viruses, and fungi. The immune system has two major types of immunity, including humoral and cell-mediated immunity. Humoral immunity is a type of adaptive immunity that is mediated by the production of antibodies by B-cells.

B-cells:
B-cells are a type of white blood cell that is responsible for producing antibodies. Antibodies are proteins that are produced by B-cells in response to the presence of foreign antigens. B-cells have receptors on their surface that can recognize specific antigens. Once a B-cell recognizes an antigen, it undergoes a process of activation, proliferation, and differentiation into antibody-secreting cells called plasma cells.

Antibodies:
Antibodies are proteins that are produced by B-cells in response to the presence of foreign antigens. Antibodies have a Y-shaped structure that consists of two heavy chains and two light chains. The tips of the Y-shaped structure contain antigen-binding sites that can recognize specific antigens. Once an antibody binds to an antigen, it can neutralize the antigen or mark it for destruction by other cells of the immune system.

Humoral immunity:
Humoral immunity is a type of adaptive immunity that is mediated by the production of antibodies by B-cells. Humoral immunity is effective against extracellular pathogens such as bacteria and viruses that are circulating in the blood or lymphatic system. In humoral immunity, B-cells recognize foreign antigens and produce antibodies that can neutralize the antigens or mark them for destruction by other cells of the immune system.

Conclusion:
In conclusion, humoral immunity is associated with B-cells. B-cells are responsible for recognizing foreign antigens and producing antibodies in response to the antigens. Antibodies can neutralize or mark the antigens for destruction by other cells of the immune system. Humoral immunity is effective against extracellular pathogens such as bacteria and viruses.

Explanation:
Vaccination is a method of providing immunity against specific diseases. It involves the introduction of a pathogen or its components into the body to stimulate an immune response. The immune response leads to the production of antibodies and memory cells, which provide protection against future infections by the same pathogen.

The form of pathogen used in vaccination is typically inactivated and weakened (option B). Let's understand why this is the case:

Activated and strong pathogenic antigens:
- Using activated and strong pathogenic antigens in vaccines can be risky as they can cause severe illness or even death in individuals with compromised immune systems.
- This approach is more suitable for therapeutic purposes, such as cancer treatment, where a highly active immune response is needed to target specific cells.

Inactivated and weakened pathogenic antigens:
- Inactivated and weakened pathogenic antigens are safer to use in vaccines as they cannot cause the disease they are derived from.
- These antigens are obtained from the pathogen and treated in a way that reduces their virulence (ability to cause disease) while preserving their ability to induce an immune response.
- The treatment may involve heat, chemicals, or genetic modifications.
- The weakened pathogenic antigens are then introduced into the body through injection or oral administration.
- The immune system recognizes these antigens as foreign and mounts a response by producing antibodies and memory cells.
- The antibodies and memory cells provide protection against future infections by the same pathogen.
- Since the pathogen is weakened or inactivated, it does not cause the disease in vaccinated individuals.

Hyperactive and strong pathogen:
- The use of hyperactive and strong pathogens in vaccination is not recommended because it can overwhelm the immune system and lead to adverse reactions or complications.
- The goal of vaccination is to stimulate a controlled immune response, not to induce severe illness or harm.

Preformed antibodies:
- Preformed antibodies are not used as the form of pathogen in vaccination.
- Preformed antibodies are antibodies that have already been produced by another individual or animal.
- They can be administered in specific cases, such as passive immunization for immediate protection against certain diseases, but they do not provide long-term immunity like vaccines.

In conclusion, the most common form of pathogen used in vaccination is inactivated and weakened pathogenic antigens. This approach ensures safety while still eliciting a protective immune response against the targeted pathogen.

Anatomy of an Antibody

An antibody, also known as an immunoglobulin, is a Y-shaped protein produced by the immune system in response to the presence of antigens. Antibodies play a critical role in the immune response by recognizing and binding to specific antigens, marking them for destruction by other immune cells.

Structure of an Antibody

An antibody consists of two light peptide chains and two heavy peptide chains, making a total of four chains. These chains are held together by disulfide bonds, creating a stable and functional structure. The light chains are shorter in length compared to the heavy chains.

Light Peptide Chains

- An antibody has two identical light peptide chains, also referred to as the L chains.
- Each light chain is composed of approximately 220-230 amino acids.
- Light chains are further divided into two regions: the variable region (VL) and the constant region (CL).
- The variable region contains antigen-binding sites that interact with specific antigens.
- The constant region determines the antibody's class or isotype.

Heavy Peptide Chains

- An antibody has two identical heavy peptide chains, also referred to as the H chains.
- Each heavy chain is longer than the light chain and consists of approximately 440-450 amino acids.
- Similar to light chains, heavy chains are divided into two regions: the variable region (VH) and the constant region (CH).
- The variable region contains antigen-binding sites that complement those of the light chains.
- The constant region determines the antibody's class or isotype.

Role of the Chains

- The heavy and light chains together form the antigen-binding fragment (Fab) of the antibody.
- The Fab region is responsible for recognizing and binding to specific antigens.
- The constant regions of the heavy chains form the antibody's crystallizable fragment (Fc), which interacts with various immune cells and molecules to initiate immune responses.

Summary

An antibody is composed of two light peptide chains and two heavy peptide chains. The light chains are shorter and consist of variable and constant regions, while the heavy chains are longer and also have variable and constant regions. Together, these chains form the antigen-binding fragment (Fab) and the crystallizable fragment (Fc), allowing antibodies to recognize and neutralize specific antigens.

Statement: HIV replicates in host cell with the help of reverse transcriptase enzyme.

Explanation:
HIV, which stands for Human Immunodeficiency Virus, is the causative agent of AIDS (Acquired Immunodeficiency Syndrome). It is a retrovirus that infects and replicates within host cells. The replication of HIV involves the use of reverse transcriptase enzyme.

What is reverse transcriptase?
Reverse transcriptase is an enzyme that aids in the synthesis of DNA from an RNA template. It catalyzes the reverse transcription process, where RNA is converted into DNA. HIV contains an RNA genome, and in order to replicate, it needs to convert its RNA into DNA.

Replication of HIV:
1. Attachment: HIV attaches itself to the surface of host cells, specifically CD4+ T cells and macrophages.
2. Fusion: The viral envelope fuses with the host cell membrane, allowing the entry of the viral core into the host cell.
3. Reverse Transcription: Once inside the host cell, the RNA genome of HIV is reverse transcribed into DNA by the reverse transcriptase enzyme. This DNA is known as cDNA (complementary DNA).
4. Integration: The newly synthesized cDNA is transported into the host cell nucleus and integrated into the host cell DNA. This integrated viral DNA is called a provirus.
5. Transcription: The provirus is transcribed into viral RNA molecules, which serve as both genomic RNA for new virus particles and as mRNA for the synthesis of viral proteins.
6. Translation and Assembly: The viral RNA is translated into viral proteins, which are then assembled into new virus particles.
7. Budding and Release: The new virus particles bud off from the host cell, acquiring an envelope from the host cell membrane. These newly formed viruses can now infect other host cells and continue the cycle of replication.

Significance of reverse transcriptase:
Reverse transcriptase plays a critical role in the replication of HIV. It allows the virus to convert its RNA genome into DNA, which can then be integrated into the host cell DNA. This DNA integration makes HIV difficult to eradicate from the body and enables the virus to persist and cause long-term infection.

Therefore, option B is the correct statement as HIV replicates in host cells with the help of reverse transcriptase enzyme.

Ascaris is an intestinal parasite that infects humans, causing a condition called ascariasis. It is a roundworm that lives in the small intestine and can grow up to 30 cm long. The female Ascaris worm can lay up to 200,000 eggs per day, which are excreted along with the infected person's faeces.

Symptoms of Ascaris infection include abdominal pain, vomiting, diarrhoea, and malnutrition. In severe cases, the worms can cause blockage of the intestinal passage, leading to an emergency situation.

Ascaris is commonly found in areas with poor sanitation and hygiene, where people are more likely to come into contact with contaminated soil or food. The eggs of the worm can survive for many months in the environment, making it difficult to control the spread of the infection.

Treatment for ascariasis involves medication to kill the worms and alleviate symptoms. Prevention measures include improving sanitation and hygiene practices, such as washing hands before eating and after using the toilet, and avoiding contact with contaminated soil or food.

Malignant tumours exhibit metastasis

Metastasis is the spread of cancer cells from one part of the body to another. Malignant tumours are cancerous growths that have the ability to invade and destroy nearby tissues and organs. These tumours can also break away from their original location and spread to other parts of the body through the bloodstream or lymphatic system. This process is known as metastasis.

Explanation:

a) Benign tumours are not cancerous and do not have the ability to invade nearby tissues or spread to other parts of the body. Therefore, they do not exhibit metastasis.

b) Heroin is a highly addictive drug that can slow down body functions and cause respiratory depression. It does not accelerate body functions.

c) Malignant tumours are cancerous growths that have the ability to invade nearby tissues and organs, and spread to other parts of the body through the bloodstream or lymphatic system. This process is known as metastasis.

d) Cannabinoids are compounds found in the cannabis plant and are used to relieve pain, nausea, and other symptoms in patients who have undergone surgery. However, the use of cannabinoids is still controversial and not widely accepted in mainstream medicine.

Therefore, the correct statement is option C - Malignant tumours exhibit metastasis.

Hey frnd!

-> allergy ~ the I gene which causes allergy is IgE
-> Helper T cells helps in activation of bone marrow cells or B- cells
-> AIDS is a single stranded RNA
-> X- rays used to detect th carcinogens
-> Treatment of cancer is immunotherapy

**Answer:**

A metastatic cancerous tumor is termed sarcoma if the disorder is in fibroblasts. Sarcomas are a type of cancer that develop from connective tissues, which include fibrous tissues such as bone, cartilage, and fibroblasts. Fibroblasts are a type of connective tissue cell that produces the extracellular matrix and collagen, which provides structural support to tissues and organs.

**Explanation:**

Sarcomas are a broad group of cancers that arise from different types of connective tissues. They are categorized based on the specific type of tissue from which they originate. Fibroblasts are a type of connective tissue cell that plays a crucial role in the maintenance and repair of tissues. They are responsible for producing the extracellular matrix, which is a complex network of proteins and carbohydrates that provides structural support to tissues and organs.

When a cancerous tumor arises from fibroblasts or the connective tissue, it is termed sarcoma. These tumors can occur in various parts of the body, including bones, muscles, tendons, and other soft tissues. Sarcomas are relatively rare compared to other types of cancer, accounting for about 1% of all cancer cases.

Sarcomas can be further classified into different subtypes based on the specific type of tissue they arise from. Some common types of sarcoma include osteosarcoma (arising from bone tissue), chondrosarcoma (arising from cartilage), and fibrosarcoma (arising from fibrous tissue).

It is important to distinguish sarcomas from carcinomas, which are cancers that arise from epithelial cells. Epithelial cells are found in the linings of organs and tissues, such as the skin, digestive tract, and respiratory tract. Carcinomas are the most common type of cancer and account for the majority of cancer cases.

In summary, a metastatic cancerous tumor is termed sarcoma if the disorder is in fibroblasts or connective tissue. Sarcomas are a diverse group of cancers that arise from different types of connective tissues and can occur in various parts of the body.

Spleen is an important organ of the lymphatic system that helps in filtering the blood and fighting against infections. Let's discuss the given statements and understand which ones are correct.

(i) Spleen is a large bean-shaped organ which mainly contains lymphocytes and phagocytes.
This statement is correct. Spleen contains lymphocytes and phagocytes which help in fighting against infections and foreign particles.

(ii) Spleen is a large reservoir of erythrocytes.
This statement is incorrect. Although spleen does store some erythrocytes, it is not a primary reservoir of erythrocytes. Its main function is to filter the blood and remove old or damaged erythrocytes.

(iii) Spleen is a primary lymphoid organ.
This statement is incorrect. Spleen is not a primary lymphoid organ. Primary lymphoid organs are bone marrow and thymus, where lymphocytes are produced and matured.

(iv) Spleen acts as a filter of the blood by trapping blood-borne microorganisms.
This statement is correct. Spleen acts as a filter of the blood by trapping blood-borne microorganisms and removing them from the circulation.

Therefore, the correct option is (d) (i), (ii) and (iv).

The correct answer is option A: (ii), (iv), and (v).

Explanation:

(i) Innate immunity is a specific type of defence, that is present at the time of birth.
This statement is incorrect. Innate immunity is a non-specific type of defense mechanism that is present at birth. It provides the first line of defense against pathogens and is not specific to any particular pathogen. It includes physical barriers like the skin, mucous membranes, and chemical barriers like enzymes and antimicrobial peptides.

(ii) Malignant malaria is caused by Plasmodium falciparum.
This statement is true. Malignant malaria, also known as cerebral malaria, is a severe form of malaria caused by the Plasmodium falciparum parasite. It is characterized by the invasion of the brain by the parasite and can lead to coma and death if not treated promptly.

(iii) Malaria could be confirmed by Widal test.
This statement is incorrect. The Widal test is not used to confirm malaria. It is a serological test used to diagnose typhoid fever caused by the Salmonella bacteria. Malaria is diagnosed through microscopic examination of blood smears or through rapid diagnostic tests that detect specific malaria antigens.

(iv) Active immunity is slow and takes time to give its full effective response.
This statement is true. Active immunity is acquired when the immune system is exposed to a pathogen or a vaccine and produces its own immune response. This process takes time as the immune system needs to recognize the pathogen, activate immune cells, and produce antibodies. It usually takes several days to weeks for the immune response to reach its full effectiveness.

(v) Saliva in the mouth acts as a physiological barrier for pathogens.
This statement is true. Saliva contains various components that act as a physiological barrier for pathogens. It contains enzymes like lysozyme and lactoferrin that can kill or inhibit the growth of bacteria. It also contains antibodies and antimicrobial peptides that can neutralize or destroy pathogens. Additionally, saliva helps to wash away pathogens from the oral cavity, reducing the risk of infection.

The first line of defence in the immune system is provided by the skin and mucous membranes.

The immune system is a complex network of cells, tissues, and organs that work together to protect the body from harmful pathogens such as bacteria, viruses, and parasites. The immune system has two main lines of defence: the innate immune system and the adaptive immune system. The first line of defence is the innate immune system, which provides immediate, non-specific protection against pathogens.

The skin and mucous membranes are the first line of defence in the immune system because they act as physical barriers that prevent pathogens from entering the body.

Role of the skin:
The skin is the largest organ in the body and serves as a physical barrier between the internal organs and the external environment. It consists of multiple layers of cells that are tightly packed together, making it difficult for pathogens to penetrate. The outermost layer of the skin, called the epidermis, is composed of dead skin cells that provide an additional layer of protection. The skin also produces sweat and sebum, which contain antimicrobial substances that can kill or inhibit the growth of pathogens.

Role of mucous membranes:
Mucous membranes are found in various parts of the body, including the respiratory tract, gastrointestinal tract, and genitourinary tract. They are made up of a layer of epithelial cells that secrete mucus, a sticky substance that traps pathogens and prevents them from entering the body. Mucous membranes also contain specialized immune cells, such as macrophages and neutrophils, which can detect and eliminate pathogens.

The importance of the first line of defence:
The skin and mucous membranes play a crucial role in protecting the body from pathogens. By preventing pathogens from entering the body, they reduce the risk of infection and disease. However, if the first line of defence is breached and pathogens manage to enter the body, the second line of defence, which includes the inflammatory response and the complement system, is activated to eliminate the pathogens.

In conclusion, the skin and mucous membranes serve as the first line of defence in the immune system by acting as physical barriers and preventing pathogens from entering the body. They play a crucial role in protecting the body from infection and disease.