General Questions in English

(B) Diseases that are easily transmitted from one person to another are known as infectious or communicable diseases. These are caused by pathogens such as bacteria,viruses,fungi,or parasites. Examples include the common cold,influenza,and $AIDS$.

(D) Infectious diseases are diseases that are easily transmitted from one person to another. These are caused by various pathogens including:
$1$. Viruses (e.g.,Common cold,Influenza).
$2$. Bacteria (e.g.,Typhoid,Pneumonia).
$3$. Fungi (e.g.,Ringworm).
$4$. Protozoa and Helminths.
Since all the listed options are known to cause infectious diseases,the correct answer is $D$.

(B) Diseases are broadly classified into two categories: infectious and non-infectious.
Infectious diseases are those that are easily transmitted from one person to another (e.g.,$AIDS$,common cold).
Non-infectious diseases are those that are restricted to the individual and do not spread from one person to another (e.g.,cancer,diabetes).
Therefore,the correct answer is $B$.

(D) The body has several innate immunity barriers that prevent the entry or destroy microorganisms:
$1$. Lysozyme: Found in tears and saliva,it acts as an antibacterial agent by breaking down bacterial cell walls.
$2$. Dilute $HCl$: Present in the stomach,it creates an acidic environment ($pH$ $1.2-2.0$) that kills most ingested pathogens.
$3$. Intestinal enzymes: Various digestive enzymes and the acidic/alkaline conditions in the gut also contribute to the destruction of pathogens.
Therefore,all the listed options contribute to the destruction of microorganisms.

(C) The human body has several innate immunity barriers to prevent the entry of pathogens.
Physical barriers are the first line of defense.
$1$. The $Skin$ is the primary physical barrier that prevents the entry of microorganisms into the body.
$2$. Mucus coating of the epithelium lining the respiratory, gastrointestinal, and urogenital tracts also helps in trapping microbes entering our body.
Therefore, the $Skin$ is considered the most significant and primary physical barrier.

(B) Colostrum,the yellowish fluid secreted by the mother during the initial days of lactation,is rich in antibodies.
Specifically,it contains a high concentration of $IgA$ antibodies.
These antibodies provide essential passive immunity to the newborn infant,protecting them from various infections during their early development.

(D) Antigens are substances that trigger an immune response in the body. They can exist in various forms:
$1$. They can be parts of $dead$ or $attenuated$ microorganisms.
$2$. They can be $living$ microorganisms that are pathogenic.
$3$. They can be specific $protein$ molecules or $polysaccharides$ found on the surface of pathogens or as toxins.
Therefore, antigens can be present in all these forms to stimulate the immune system.

(A) Antigens are substances that induce an immune response in the body. Chemically,most antigens are proteins,polysaccharides,or glycoproteins. However,among the given options,antigens are primarily recognized as proteins or polypeptides because they are composed of amino acid chains that the immune system recognizes as foreign. While they can be complex molecules,the most accurate classification in the context of basic immunology is that they are often polypeptide or proteinaceous in nature.

(B) Modern lifestyle factors such as high stress,lack of physical exercise,poor dietary habits (consumption of junk food),and increased exposure to pollution contribute to a weakened immune system.
Consequently,the body's ability to fight off pathogens is compromised,leading to a decrease in overall immunity.

(A) The spleen is a large bean-shaped organ which mainly contains lymphocytes and phagocytes.
It acts as a filter of the blood by trapping blood-borne microorganisms.
It also has a large reservoir of erythrocytes.
Since the spleen acts as a lymphoid organ that filters blood and stores lymphocytes,both the assertion and the reason are true,and the reason correctly explains why the spleen is considered a reservoir of lymphocytes and a filter for blood-borne pathogens.
Therefore,the correct option is $A$.

(B) The $Spleen$ is a large,bean-shaped organ primarily composed of lymphocytes and phagocytes.
It acts as a filter for the blood by trapping blood-borne microorganisms.
It also contains a large reservoir of erythrocytes (red blood cells).

(D) The lymphatic system consists of a network of vessels and organs.
Small,solid,bean-shaped structures found at various points along the lymphatic vessels are called $Lymph \ nodes$.
These nodes are responsible for trapping microorganisms or other antigens that enter the lymph and tissue fluid.
They are the sites where lymphocytes are activated and lead to an immune response.

(A) $ELISA$ stands for Enzyme Linked Immuno Sorbent Assay.
It is a diagnostic technique based on the principle of antigen-antibody interaction.
Infection by pathogens can be detected by the presence of antigens (proteins,glycoproteins,etc.) or by detecting antibodies synthesized against the pathogen.

(C) $WHO$ stands for World Health Organization.
It is a specialized agency of the United Nations responsible for international public health.
It was established on $7$ April $1948$ and is headquartered in Geneva,Switzerland.

(B) The term 'Epidemic' refers to the rapid spread of an infectious disease to a large number of people in a given population within a short period of time.
It is characterized by a sudden increase in the number of cases of a disease above what is normally expected in that population in that area.

(A) Smoking is a major risk factor for several diseases,including $Lung \ cancer$,$Emphysema$,and $Gastric \ ulcers$.
$Malaria$ is a vector-borne infectious disease caused by $Plasmodium$ parasites,which are transmitted to humans through the bite of an infected female $Anopheles$ mosquito.
Therefore,$Malaria$ is not caused by smoking.

(A) Smoking is a major risk factor for various diseases including lung cancer,bronchitis,emphysema,and gastric ulcers.
$A$. Malaria is a vector-borne infectious disease caused by protozoan parasites of the genus $Plasmodium$,which is transmitted by the bite of an infected female $Anopheles$ mosquito.
$B$. Laryngitis (inflammation of the larynx) is often exacerbated or caused by smoking.
$C$. Lung cancer is strongly associated with chronic smoking.
$D$. Gastric ulcers are linked to smoking as it increases stomach acid production and impairs the healing of the stomach lining.
Therefore,malaria is the only disease listed that is not caused by smoking.

(C) According to the World Health Organization $(WHO)$,health is not merely the absence of disease or infirmity but a state of complete physical,mental,and social well-being. Therefore,the given definition refers to $Health$.

(D) Good health is not just the absence of disease but a state of complete physical,mental,and social well-being.
$1$. Increased productivity: Healthy individuals can work more effectively,leading to higher output.
$2$. Economic prosperity: $A$ healthy population contributes more to the economy,leading to better financial stability for individuals and the nation.
$3$. Increased efficiency: Health improves the functional capacity of the body and mind,allowing individuals to perform tasks with greater efficiency.
Therefore,all the given options are correct consequences of good health.

(D) Maintaining good health is a multifaceted process that requires a holistic approach.
$1$. $Balanced diet$ provides the essential nutrients, vitamins, and minerals required for the proper functioning of the body.
$2$. $Personal hygiene$ is crucial to prevent the accumulation of pathogens and to reduce the risk of infectious diseases.
$3$. $Regular exercise$ improves cardiovascular health, strengthens muscles, and boosts the immune system.
Therefore, all these factors are essential for maintaining optimal health.

(B) Yoga has been practiced for thousands of years to achieve physical and mental well-being. It is an ancient practice that involves physical postures,breathing techniques,and meditation to improve overall health and reduce stress.

(D) Maintenance of good health requires a multi-faceted approach.
$1$. Vaccination against infectious diseases helps in building immunity and preventing outbreaks.
$2$. Awareness about diseases is crucial for early detection and prevention.
$3$. Control of vectors (like mosquitoes) is essential to prevent the spread of vector-borne diseases.
Therefore,all the given options are necessary for maintaining good health.

(D) Health is defined as a state of complete physical,mental,and social well-being. We realize that we are not healthy when:
$1$. The normal functioning of various body organs is disturbed.
$2$. The physiological processes of various body systems are adversely affected.
$3$. Visible symptoms of diseases or disorders appear in the body.
Therefore,all the given options indicate a state of ill health.

(D) Personal health maintenance involves a holistic approach to hygiene and lifestyle.
$1$. Clean water is essential to prevent water-borne diseases like cholera and typhoid.
$2$. Clean food ensures the intake of proper nutrients and prevents food poisoning or infections.
$3$. Clean clothes and personal hygiene help in preventing skin infections and maintaining overall cleanliness.
Therefore,all these factors are crucial for maintaining personal health.

(D) To prevent water-borne diseases,it is essential to maintain public health through multiple strategies:
$1$. Proper disposal of sewage and excreta prevents the contamination of drinking water sources.
$2$. Disinfection of water reservoirs,such as dams and tanks,using chemicals like chlorine or ozone,kills pathogenic microorganisms.
$3$. Periodic cleaning of water storage tanks prevents the accumulation of sediments and the growth of biofilms or pathogens.
Therefore,all the mentioned measures are crucial for public health.

(D) Mosquitoes act as vectors for various diseases like malaria,dengue,and chikungunya. These mosquitoes breed in stagnant water. Therefore,to prevent these diseases,it is essential to:
$1$. Eliminate stagnant water pools around residential areas to prevent breeding sites.
$2$. Regularly change the water in coolers,as they are common breeding grounds.
$3$. Spray insecticides in pits,drains,and sewage areas to kill larvae and adult mosquitoes.
Thus,all the given measures are effective in controlling mosquito-borne diseases.

(A) To prevent mosquitoes from entering the house,the most effective physical barrier is to fit wire mesh on windows and doors. This prevents the entry of adult mosquitoes into the living space. While options $C$ and $D$ are methods for controlling mosquito larvae,they do not prevent mosquitoes from entering the house. Option $B$ is irrelevant to preventing entry.

(D) Vaccines are biological preparations that provide active acquired immunity to a particular infectious disease.
$1$. Polio is prevented by the Oral Polio Vaccine $(OPV)$ or Inactivated Polio Vaccine $(IPV)$.
$2$. Diphtheria is prevented by the $DPT$ vaccine (Diphtheria,Pertussis,and Tetanus).
$3$. Tetanus is also prevented by the $DPT$ vaccine or Tetanus Toxoid $(TT)$ injection.
Since all these diseases have effective vaccines available for their prevention,the correct answer is $D$.

(D) The mucosal lining is a type of physical barrier in the innate immune system.
It is present in the lining of the respiratory,gastrointestinal,and urogenital tracts.
These linings trap microorganisms entering our body and prevent them from causing infection.
Therefore,all the given options contain a mucosal lining.

(C) $PMNL$ stands for Polymorphonuclear Leukocytes.
These are a type of white blood cell characterized by a multi-lobed nucleus.
Neutrophils are the most common type of $PMNL$ and act as a primary cellular barrier in innate immunity by performing phagocytosis to destroy pathogens.

(C) Innate immunity consists of four types of barriers: Physical,Physiological,Cellular,and Cytokine barriers.
$1$. Physical barriers include skin and mucus coatings of the respiratory,gastrointestinal,and urogenital tracts.
$2$. Physiological barriers include acid in the stomach,saliva in the mouth,and tears from eyes,which prevent microbial growth.
$3$. Cellular barriers include leukocytes like polymorphonuclear leukocytes ($PMNL$-neutrophils),monocytes,and natural killer cells.
$4$. Cytokine barriers include interferons which protect non-infected cells from further viral infection.
Therefore,saliva in the mouth is a physiological barrier.

(B) The human body has several lines of defense against pathogens.
Physical barriers are the first line of defense.
The skin and the mucus coating of the epithelium lining the respiratory,gastrointestinal,and urogenital tracts are the primary physical barriers.
These barriers trap microorganisms and prevent their entry into the body.
Therefore,the mucus coating acts as a physical barrier.

(B) Physiological barriers in the human body prevent the entry of microorganisms by creating an environment that is hostile to them.
$1$. Skin is a physical barrier.
$2$. Tears (from eyes) and saliva (in the mouth) contain lysozyme and act as physiological barriers.
$3$. The acid in the stomach is also a physiological barrier.
$4$. Monocytes are cells involved in cellular barriers.
Therefore,among the given options,tears act as a physiological barrier.

(B) An autoimmune disorder occurs when the immune system mistakenly attacks the body's own healthy cells.
$1$. Multiple sclerosis is an autoimmune disease where the immune system attacks the protective sheath (myelin) that covers nerve fibers.
$2$. Rheumatoid arthritis is also an autoimmune disease where the immune system attacks the joints.
Since both $B$ and $C$ are autoimmune disorders, in the context of standard biology questions, $Multiple \text{ } sclerosis$ is a classic example of a central nervous system autoimmune disorder, while $Rheumatoid \text{ } arthritis$ is a classic example of a systemic autoimmune disorder. Given the options, both are correct, but $Multiple \text{ } sclerosis$ is frequently cited in textbooks.

(A) Antibiotics are chemical substances produced by microorganisms that can kill or inhibit the growth of other microorganisms,specifically bacteria.
Since the common cold is caused by a virus (such as the Rhinovirus),antibiotics are ineffective against it.
Antibiotics target specific bacterial metabolic pathways (like cell wall synthesis or protein synthesis) which are absent in viruses.
Therefore,the correct reason is that the common cold is caused by a virus.

(D) $DPT$ is a combination vaccine used to protect against three infectious diseases:
$1$. $D$ stands for Diphtheria.
$2$. $P$ stands for Pertussis (also known as whooping cough).
$3$. $T$ stands for Tetanus.
Therefore,the correct option is $D$.

(B) Alexander Fleming discovered penicillin in $1928$.
Later,Ernst Chain and Howard Florey were instrumental in establishing its full potential as an effective antibiotic.
For their pioneering work in the discovery and development of penicillin,Alexander Fleming,Ernst Chain,and Howard Florey were jointly awarded the Nobel Prize in Physiology or Medicine in $1945$.
Therefore,the correct combination is $(i), (iv),$ and $(v)$.

(D) The discovery of antibiotics is one of the most significant achievements of the $20^{th}$ century. Alexander Fleming discovered the first antibiotic, Penicillin, in $1928$ from the mold Penicillium notatum. This discovery revolutionized the field of medicine by providing a cure for many deadly bacterial infections.

(B) Antibiotics are chemical substances produced by some microorganisms that can kill or retard the growth of other disease-causing microorganisms.
$A$. Carbamycin is an antibiotic.
$B$. Insulin is a peptide hormone produced by the pancreas that regulates blood glucose levels; it is not an antibiotic.
$C$. Bacitracin is an antibiotic.
$D$. Tetracycline is a broad-spectrum antibiotic.
Therefore,the correct answer is $B$.

(C) Alzheimer's disease is a progressive neurodegenerative disorder that primarily affects the brain.
It is characterized by the accumulation of amyloid plaques and tau tangles,leading to memory loss and cognitive decline.
This condition is specific to humans and is not found in bacteria,fungi,or plants like potatoes.
Therefore,the correct option is $C$.

(C) Alzheimer's disease is a progressive neurodegenerative disorder.
It is primarily characterized by the accumulation of misfolded proteins in the brain,specifically $Amyloid-beta$ plaques and $Tau$ protein tangles.
These misfolded proteins lead to the death of nerve cells and the loss of cognitive function.
Among the given options,$Protein \text{ } misfolding$ is the correct biological mechanism responsible for the disease.
Viruses,bacteriophages,and bacteria are not the causative agents of Alzheimer's disease.

(D) Louis Pasteur is widely recognized for his pioneering work in microbiology. He demonstrated that microorganisms are responsible for fermentation and spoilage,which led to the development of the process of pasteurization. Furthermore,he made significant contributions to the germ theory of disease,proving that specific microorganisms are responsible for infectious diseases,and he developed vaccines for diseases such as rabies and anthrax.

(B) The correct answer is $B$. Antivenom provides passive immunity by introducing preformed antibodies directly into the body. In contrast,polio drops (oral polio vaccine) contain attenuated (weakened) pathogens. When these weakened pathogens enter the body,they stimulate the immune system to produce specific antibodies,thereby providing active immunity.

(C) : Borderline personality disorder $(BPD)$ is a serious mental illness characterized by pervasive instability in moods, interpersonal relationships, self-image, and behaviour.
This instability often disrupts family and work life, long-term planning, and the individual's sense of self-identity.
Originally thought to be at the "borderline" of psychosis, people with $BPD$ suffer from a disorder of emotion regulation.
Schizophrenia is a group of severe mental disorders characterized by disturbances of language and communication; thought disturbances that may involve distortion of reality, misperceptions, delusions and hallucinations; mood changes and withdrawn, regressive, or bizarre behaviour, lasting longer than six months.
$A$ mood disorder is a condition where the prevailing emotional mood is distorted or inappropriate to the circumstances.
Addiction is a state of dependence produced by the habitual taking of drugs, alcohol, etc.

(A) The human body has various innate immunity barriers to prevent the entry of pathogens.
$1$. Physical barriers: These include the skin and the mucus coating of the epithelium lining the respiratory,gastrointestinal,and urogenital tracts.
$2$. Physiological barriers: These include acid in the stomach,saliva in the mouth,and tears from the eyes,which prevent microbial growth.
$3$. Cellular barriers: These include leukocytes like $PMNL$-neutrophils,monocytes,and macrophages.
Since saliva prevents microbial growth in the mouth,it is classified as a physiological barrier. Therefore,the correct option is $A$.

(A) The human immune system consists of various barriers that prevent the entry of pathogens.
Skin is the primary physical barrier of the body.
It prevents the entry of microorganisms by acting as a mechanical wall.
Physiological barriers include acid in the stomach and saliva in the mouth.
Cellular barriers include leukocytes like neutrophils and macrophages.
Cytokine barriers include interferons secreted by virus-infected cells.
Therefore,the correct option is $A$.

(D) The correct answer is $D$.
$PMNL$ (Polymorphonuclear leukocytes),Monocytes,and Macrophages are all types of cellular barriers that provide innate immunity by phagocytosing and destroying microbes.
Lysozyme is an enzyme found in tears and saliva that provides physiological barriers by preventing microbial growth.
Therefore,Lysozyme is the odd one out as it is a chemical/physiological barrier,while the others are cellular barriers.

(C) $1$. $Elephantiasis$ (Filariasis) is transmitted by the bite of $Culex$ mosquitoes.
$2$. $Malaria$ is transmitted by the bite of female $Anopheles$ mosquitoes.
$3$. $Dengue$ is transmitted by the bite of $Aedes$ mosquitoes.
$4$. $Typhoid$ is a bacterial disease caused by $Salmonella$ $typhi$,which is transmitted through contaminated food and water (fecal-oral route),not by mosquitoes.

(C) Phagocytosis is a process by which cells engulf and digest cellular debris,foreign substances,or pathogens.
$1$. $PMNL$ (neutrophils) are well-known phagocytic cells.
$2$. Monocytes differentiate into macrophages,which are primary phagocytic cells.
$3$. Natural killer cells are a type of lymphocyte that destroy infected or cancerous cells via apoptosis and cytokine release,but they are not primarily phagocytic.
$4$. Mast cells are involved in allergic reactions and inflammatory responses by releasing histamine and heparin; they are not phagocytic cells.
Among the given options,both Natural killer cells and Mast cells are not phagocytic. However,in the context of standard biology questions regarding innate immunity,Mast cells are the most distinct non-phagocytic cells compared to the others listed.

(C) An antibody molecule is composed of four polypeptide chains: two identical light chains $(L)$ and two identical heavy chains $(H)$.
These chains are held together by disulfide bonds to form a $Y$-shaped structure,represented as $H_2L_2$.
While $IgM$ is a pentamer (composed of five $H_2L_2$ units) and $IgA$ can exist as a dimer,the basic structural unit of all antibody classes is the $H_2L_2$ monomer.
Therefore,the general representation for the basic structure of an antibody is $H_2L_2$.