RBSE Solutions Class 12 Biology Chapter 39 Immune System

RBSE Class 12 Biology Chapter 39 Multiple Choice Questions

 

Question 1. Which cell is involved in cell-mediated immunity -
(a) Leukaemia
(b) mast cell
(c) T cell
(d) Thrombocytes
Answer: (c) T cell
In simple words: T cells are very important white blood cells that directly fight against infections and abnormal cells like cancer cells. They are a key part of how our body defends itself.

🎯 Exam Tip: Remember that "cell-mediated immunity" specifically points to the role of T cells, distinguishing it from "humoral immunity" which involves B cells and antibodies.

 

Question 2. Antigen is -
(a) a substance that causes an immune response
(b) a type of antibody
(c) a protein found in red blood cells
(d) a hormone that regulates cell growth
Answer: (a) a substance that causes an immune response
In simple words: An antigen is like a "flag" on foreign invaders (like viruses or bacteria) that tells your body's immune system to start fighting them. It triggers a defense reaction.

🎯 Exam Tip: Always associate antigens with "triggering an immune response" and antibodies with "fighting that response" for clarity.

 

Question 3. Which antibody is involved in hypersensitivity/allergic reaction?
(a) IgG
(b) IgA
(c) IgE
(d) IgM
Answer: (c) IgE
In simple words: IgE is the special antibody that causes allergic reactions. When you get exposed to something you are allergic to, IgE antibodies make your body release chemicals that cause allergy symptoms.

🎯 Exam Tip: Link IgE directly with allergies and hypersensitivity, as this is its primary role in the immune system.

 

Question 4. Which antibody is transmitted from mother placenta to embryo?
(a) IgG
(b) IgA
(c) IgE
(d) IgM
Answer: (a) IgG
In simple words: IgG is a type of antibody that can pass from a mother to her unborn baby through the placenta. This helps to protect the baby from diseases even before it is born.

🎯 Exam Tip: Remember that IgG is the only antibody capable of crossing the placenta, providing passive immunity to the fetus.

 

Question 5. What is produced in the body by vaccination?
(a) Plasma
(b) Histamine
(c) Antibody
(d) Toxoid
Answer: (c) Antibody
In simple words: Vaccinations make your body produce antibodies, which are special proteins that learn to fight off certain diseases. This teaches your body how to protect itself in the future.

🎯 Exam Tip: Vaccination trains your immune system to recognize and fight specific pathogens by generating antibodies and memory cells.

RBSE Class 12 Biology Chapter 39 Very Short Answer Type Questions

 

Question 1. What are the types of immunity?
Answer: Immunity is broadly categorized into five types, allowing the body to defend against a wide range of threats. These different types of immunity work together to provide comprehensive protection against diseases.
In simple words: There are five main ways our body fights off sickness.

🎯 Exam Tip: When asked about types, always list the main categories, even in a very short answer, to show comprehensive knowledge.

 

Question 3. Which is the most abundantly found antibody?
Answer: Immunoglobulin (IgG) is the most abundantly found antibody in the body. It plays a crucial role in protecting against bacterial and viral infections and is the only antibody that can cross the placenta.
In simple words: IgG is the most common antibody in our body.

🎯 Exam Tip: Always remember IgG as the most prevalent antibody and its ability to cross the placenta for maternal immunity.

 

Question 4. Which kind of response is responsible to destroy tumour?
Answer: Monoclonal antibodies (MAB) and cell-mediated immunity are responsible for destroying tumors. These methods specifically target and eliminate cancerous cells from the body, offering a precise defense against abnormal cell growth.
In simple words: Special antibodies and cell immunity help destroy tumors.

🎯 Exam Tip: Mention both monoclonal antibodies and cell-mediated immunity when discussing tumor destruction, as they represent distinct yet powerful mechanisms.

 

Question 5. Name some vaccine which is made up of Killed or inactivated pathogens.
Answer: Vaccines made from killed or inactivated pathogens include Polio injection, Hepatitis A, Rabies, Cholera, and Typhoid vaccines. These vaccines teach the body to recognize the dead germs without causing the disease itself.
In simple words: Polio shots, Hepatitis A, Rabies, Cholera, and Typhoid vaccines use dead or inactive germs to protect you.

🎯 Exam Tip: When listing examples, try to include a variety of well-known diseases to demonstrate a broad understanding of vaccine types.

 

Question 6. Who is known as the father of Immunology?
Answer: Edward Jenner is known as the father of Immunology. His pioneering work on the smallpox vaccine laid the foundation for modern immunology and public health efforts.
In simple words: Edward Jenner is called the father of Immunology because he created the first vaccine for smallpox.

🎯 Exam Tip: Always associate Edward Jenner with the development of the smallpox vaccine and his pivotal role in the history of immunology.

RBSE Class 12 Biology Chapter 39 Short Answer Type Questions

 

Question 1. Write the definition of Immunity.
Answer: Immunity is the body's ability to resist diseases, microorganisms, or toxic products. The word "Immunity" comes from the Latin word "Immunis," which means "free of burden," highlighting the body's capability to protect itself from infectious factors. Immunology is the scientific field dedicated to studying immunity, including the immune system's components and functions.
In simple words: Immunity is how our body fights off sickness and harmful germs. Immunology is the study of how this defense system works.

🎯 Exam Tip: When defining immunity, always mention its core function of resistance and, if space allows, its etymological root to show a deeper understanding.

 

Question 2. Name the main physiological barrier.
Answer: Many bodily activities act as physiological barriers to prevent germs from entering. Some of these important barriers are:

• Fever: When germs invade, they release toxins. The body increases white blood cells (WBCs) and macrophages, which produce pyrogens. These pyrogens raise body temperature, stopping bacteria from growing.
• Lysozyme: Body secretions like tears, saliva, and sweat contain lysozyme, an enzyme that kills germs by breaking down their cell walls.
• Stomach Acid: The stomach makes dilute HCl, creating a very acidic environment (pH 1 to 2) that acts as a strong germ killer.
• Bile Juice: Bile juice released into the duodenum also helps kill germs.
• Mucus: Mucus in the respiratory passages traps germs, acting as a barrier.
• Cerumin: Cerumin in the sebum from skin glands also kills germs. These barriers are our body's first line of defense against illness.

In simple words: Our body uses fever, stomach acid, tears, mucus, and skin oils as natural ways to stop germs from getting inside and making us sick.

🎯 Exam Tip: When listing physiological barriers, provide specific examples and briefly explain how each one functions to stop pathogens.

 

Question 3. Write the difference between active acquired immunity and inactive acquired immunity.
Answer:
Active Immunity:

• It develops in the blood when an antigen or germ enters the body. It is also known as humoral immunity.
• This process is slow, but it provides long-lasting protection.
• Natural active immunity is gained when a person gets sick from a pathogen.
• Artificial active immunity is acquired through vaccination with inactivated pathogens or antigens. The body creates its own defenses.

Passive Immunity:

• This type of immunity is acquired by receiving ready-made antibodies or sensitized white blood cells from another immune individual.
• The protection is temporary and generally less effective, as the body doesn't produce its own immune response.
• IgG antibodies can pass from a mother to her baby through the placenta.
• IgA antibodies are transferred from mother to child through colostrum (first breast milk).

In simple words: Active immunity means your body makes its own defense (like after getting sick or a vaccine), which lasts long. Passive immunity means you get defense from outside (like from mom or an injection), but it doesn't last as long.

🎯 Exam Tip: Clearly differentiate between active and passive immunity by focusing on whether the body *generates* its own immune response or *receives* pre-formed components.

 

Question 4. Write a note on humoral Immunity.
Answer:

• Humoral immunity develops in the blood, where lymphocytes produce various globulin proteins (antibodies) to destroy different antigens.
• These lymphocytes mainly come from mesodermal stem cells, but some also form in the thymus gland and bone marrow.
• When an antigen, like bacteria or a virus, enters the body, lymphocytes in lymphatic organs quickly divide and change into plasma cells. These plasma cells then produce the specific antibodies needed to fight the invader.
• Humoral immunity protects the body from infections like tetanus, common cold, smallpox, and measles. It is a key part of our defense system that uses circulating antibodies.

In simple words: Humoral immunity is a body defense system where special white blood cells make antibodies that float in the blood and find and destroy germs.

🎯 Exam Tip: When explaining humoral immunity, emphasize the role of B-cells, plasma cells, and the production of antibodies that circulate in bodily fluids.

 

Question 5. Write a note on T cell.
Answer: T-cells are crucial for cellular immune responses. They mature in the thymus gland after originating in the bone marrow and then travel to secondary lymphoid organs like lymph nodes and the spleen. When T-cells encounter an antigen, they multiply and transform into various types, including:

• Killer T-cells (Cytotoxic T-cells): These cells directly destroy infected or abnormal target cells, such as tumor cells, by releasing substances that create holes in the cell membrane, causing the target cell to break apart.
• Helper T-cells: These are the most common T-cells, making up about 75% of the total. They stimulate B-cells to produce antibodies and support the actions of other T-cells. Helper T-cells also release lymphokines, which are messenger molecules that attract other white blood cells to the infection site.
• Suppressor T-cells (Regulatory T-cells): These cells act as "peacemakers" by protecting the body's own healthy cells from immune attack. They regulate the immune response, releasing substances that switch off B-cells and tell killer T-cells to stop fighting once the threat is managed.

These different T-cell types coordinate to provide targeted defense against intracellular pathogens and abnormal cells.
In simple words: T-cells are specialized immune cells that directly fight germs and sick cells. Some kill, some help other cells, and some tell the immune system to stop attacking once the danger is gone.

🎯 Exam Tip: For T-cells, remember to detail the specific roles of Killer (cytotoxic), Helper, and Suppressor T-cells, as each has a distinct function in cell-mediated immunity.

RBSE Class 12 Biology Chapter 39 Essay Type Questions

 

Question 1. Write a detailed note on the various cell involved in the immune system.
Answer: The immune system relies on the coordinated activity of two main types of lymphocytes: B-cells and T-cells. Both originate from precursor cells produced in the bone marrow. The body's defense mechanisms are complex, involving both direct cell-to-cell combat and antibody production.
1. B-Lymphocytes:

• They originate from stem cells found in the bone marrow.
• B-lymphocytes mature in the liver during the embryonic stage and in the bone marrow in adult mammals.
• In birds, B-cell maturation happens in an organ called the bursa of Fabricius, which is located in the dorsal wall of the proctodaeum, giving them the name "B-lymphocyte."
• Mature B-cells that do not change into plasma cells become memory B cells.
• These memory cells are crucial because they allow the body to respond much faster and more strongly if the same antigen attacks the body again in the future.

2. T-Lymphocytes:

• T-cells are responsible for cellular immune responses. They leave the bone marrow and mature in the thymus, a special organ.
• After maturing, these T-cells travel to secondary lymphoid organs like lymph nodes, tonsils, and the spleen. In these organs, they can become active to produce antibodies or T-cell receptors.
• These cells then circulate between the blood system and the lymph.
• When a T-cell identifies an antigen, it multiplies and differentiates into several specialized types: Killer (or cytotoxic) T-cells, Helper T-cells, and Suppressor T-cells.
• Killer T-cells (or N.K. cells/Natural Killer cells): These cells destroy target cells by releasing substances that dissolve and create holes in the target cell's plasma membrane, causing the cell to break open.
• These substances are proteins called perforins, which punch large, round holes in the plasma membrane of the attacked cells.
• Helper T-cells: These are the most common T-lymphocytes, making up about 75% of the total. They stimulate B-cells to make antibodies and help other T-cells function effectively.
• Some helper T-cells secrete lymphokines, which are messenger molecules that attract other white blood cells to the site of infection.
• Important lymphokines secreted by helper T-cells include Interleukin, Granulocyte-monocyte colony-stimulating factor, and Interferon (an antiviral substance).
• Helper T-cells are also known as T4 or HT cells. Some of these cells rush to the spleen and lymph nodes to alert B-cells about the antigen.
• Suppressor T-cells (ST-Cells): Also called peacemaker cells, they protect the body's own healthy cells from attack, a process known as immune tolerance.
• Suppressor T-cells, along with helper T-cells, are collectively called regulatory T-cells.
• ST-cells release substances that switch off B-cells and instruct killer T-cells to stop fighting.
• During this "peace interval," phagocytes move into the area to remove cell debris and dead cells, helping to clean up the site.
• Phagocytes also consume anything suspicious in the blood, tissues, and lymph system, and clean dust and smoke from the lungs.
• They secrete interleukin-1, which stimulates helper T-cells to produce interleukin-2 and encourages B-cell growth.

In simple words: Our immune system uses B-cells and T-cells to fight sickness. B-cells make antibodies that find germs, and T-cells directly kill infected cells or help other immune cells. They both work together to keep us healthy.

🎯 Exam Tip: For essay questions on immune cells, ensure you describe the origin, maturation, and specific functions of both B-cells and T-cells, including their various subtypes.

 

Question 2. Define the immune system and also explain its types.
Answer: The immune system is the body's protective network that defends against diseases. Immunology is the study of this system, including its parts and how they work. Our body’s amazing ability to tell the difference between its own cells and foreign invaders is key to this defense.
Immunity and Immunology:

• Immunity is the body's ability to fight off diseases, microorganisms, or toxic products. The word "Immunity" comes from the Latin word "Immunis," meaning "free of burden," highlighting the body's ability to protect itself.
• Immunology is the branch of science that studies immunity, including the components of the immune system and their functions.
• The immune system provides protection against pathogens and helps maintain overall health.
• Our body can distinguish between its own cells ("self") and foreign materials ("non-self"). It responds to foreign invaders by eliminating them with an immune response.

Types of Immunity:
Immunity is generally divided into two main types:
1. Natural or Innate Immunity:

• This type of immunity is present from birth, meaning it is inborn.
• It does not depend on prior exposure to pathogens.
• Innate immunity includes various physical, physiological, and cellular barriers that act as the first line of defense against invading germs.

Physical Barrier:
It stops disease-causing agents from entering the body and is the first line of defense. Key organs involved include:
1. Skin:

• It is the very first line of defense.
• The outer layers of the epidermis are made of dead cells with keratin protein, forming a barrier that germs cannot easily pass through.
• The dermis has many sebaceous glands that produce an oily substance called Sebum.
• Sebum contains lactic acid and fatty acid, which keep the skin's pH between 3 to 5.
• Most microorganisms, including many bacteria, cannot survive or grow in this acidic pH.

2. Mucous Membrane:
Mucous membranes act as an important barrier. These membranes line many parts of the body, like the respiratory and digestive tracts. They trap germs and prevent them from entering deeper tissues. Special cells within the membranes produce mucus, which is a sticky substance that catches particles and microorganisms.
Physiological Barriers:
These bodily activities naturally prevent germ entry:

• Fever: Invading germs release toxins, increasing WBCs and macrophages, which secrete pyrogens. These raise body temperature, inhibiting bacterial growth.
• Lysozyme: Secretions like tears, saliva, and sweat contain lysozyme, an enzyme that digests bacterial cell walls, killing germs.
• Stomach Acid: The stomach secretes dilute HCl (pH 1-2), acting as a strong germicidal.
• Bile Juice: Released into the duodenum, bile also has germicidal properties.
• Mucus: Secreted in the respiratory passage, mucus acts as a barrier to trap germs.
• Cerumin: Found in sebum from sebaceous glands on the skin, cerumin also kills germs.

Cellular Phagocytic Barrier:
This is a key part of Innate Immunity, involving special cells that destroy germs through phagocytosis (eating them). E. Metchnikoff discovered this process. These phagocytic cells include:
1. Leucocytes or WBC (White Blood Cells):

• Any infection leads to Leucocytosis (an increased number of WBCs). Neutrophil WBCs destroy germs by phagocytosis; they contain phagocytic and lactoferrin components, which are antibacterial.
• Monocyte WBCs also destroy germs through phagocytosis.
• Lymphocyte WBCs are of two types – B and T lymphocytes, which destroy germs by forming antibodies.

2. Macrophages:

• These are modified monocytes that perform phagocytosis.
• Macrophages in the blood stimulate the formation of antigen-antibody complexes.
• Macrophages found at infection sites kill germs directly through phagocytosis.
• Mast cells and basophils of WBC in connective tissue release chemical indicators like Histamine and Prostaglandin.
• These secretions make blood cells more permeable, allowing plasma and phagocytes to exit and function effectively.
• Serum also has the ability to destroy bacteria.

Acquired Immunity:

• This immunity is not present from birth but is gained after birth, based on the body's memory. It is also called adaptive immunity.
• It is obtained through antibody development in response to an antigen (from vaccination or infection) or through the transfer of antibodies (from mother to fetus or through antiserum injections).
• Acquired immunity provides the body's third line of defense.
• It is highly specific to a particular antigen. When an antigen enters the body for the first time, the immune system produces a specific antibody, which is called the Primary Response.
• During this response, memory cells are formed. When the immune system encounters the same foreign agent (e.g., a microbe) a second time, it generates a faster and stronger immune response, called the Secondary Response.
• This immune system remembers the first encounter, leading to a quicker and more abundant response upon subsequent exposures.

Acquired immunity is of two types:
1. Active Immunity:

• It develops in the blood when an antigen or germ enters the body. Hence, it is also called humoral immunity.
• It is a slow process but it acts for a long duration.
• Natural active immunity is acquired by exposure of an organism to pathogens.
• Artificial active immunity is acquired through vaccination of inactivated pathogen or antigen.

2. Passive Immunity:

• The immunity that an individual acquired by receiving antibodies or sensitized white blood cells from another immune individual is known as Passive immunity.
• The protection, however, is temporary and usually less effective.
• IgG antibodies can cross the placental barrier to reach the fetus.
• IgA antibodies are transferred from mother to child in the form of colostrum.

Auto Immunity:

• Autoimmunity is present to some extent in everyone and is usually harmless.
• However, autoimmunity can cause a broad range of human illnesses, known collectively as Autoimmune disease.
• Autoimmune disease occurs when there is a progression from being autoimmunity to pathogenic autoimmunity.
• This progression is determined by genetic influences as well as environmental triggers.
• Example: Rheumatoid Arthritis.

In simple words: The immune system is our body's defense against sickness. There are two main kinds: innate immunity (what we are born with, like skin and fever) and acquired immunity (what we get over time, like from vaccines or getting sick). Acquired immunity can be active (body makes its own defense) or passive (gets defense from outside). Sometimes, the body can mistakenly attack itself, which is called autoimmunity.

🎯 Exam Tip: When defining the immune system, highlight its distinction between "self" and "non-self." For types, clearly describe innate vs. acquired immunity and their subcategories, providing brief examples for each.

 

Question 3. Define vaccination and explain their types.
Answer: Vaccination is a medical procedure that helps the body build immunity to a specific disease without actually getting sick. It involves introducing a weakened or inactivated form of a pathogen, or parts of it, to stimulate the immune system to produce antibodies and memory cells. Edward Jenner, often called the "Father of Vaccination," pioneered this field with his work on the smallpox vaccine, notably using fluid from a cowpox blister to immunize James Fipps. This has been a major achievement in public health.

Types of Vaccine:
Vaccines are categorized into several types based on how they are prepared:
1. Live or Attenuated Vaccines:

• These vaccines contain a living but weakened version of the pathogen.
• They can be made by passing the pathogen virus through a series of cell cultures or animal embryos (often chick embryos).
• With each passage, the virus loses its ability to replicate strongly in human cells.
• Examples include Measles, Mumps, Rubella (MMR), nasal spray Influenza, Rotavirus, and Oral Polio Vaccine (OPV).

2. Killer or Inactivated Vaccines:

• These vaccines use pathogens that have been killed or inactivated, so they cannot cause disease.
• They stimulate an active acquired immunity to a specific disease.
• Examples include Polio injection (IPV), Hepatitis A, Rabies, Typhoid, and Diarrhea vaccines.

3. Toxoid Vaccine:

• Some diseases are caused not directly by the bacterium but by toxins it produces, such as Tetanus.
• For example, Tetanus symptoms are caused by a neurotoxin produced by the Clostridium tetani bacterium.
• Immunizations for these diseases involve inactivating the toxins that cause symptoms, creating toxoids.
• Examples include Tetanus and Diphtheria vaccines.
• Immunizations made using inactivated toxins are called toxoids.

4. Conjugate Vaccines or Subunit Vaccine:

• These vaccines contain only parts or pieces of the pathogens they protect against.
• Subunit vaccines use just a target pathogen component to trigger an immune response.
• This can be done by isolating a specific protein from a pathogen and presenting it as an antigen.
• Examples include Pertussis vaccine and Influenza vaccine.

5. Engineered Vaccine or Recombinant Vaccine:

• These vaccines are produced on a large scale using genetic engineering techniques, often with the help of yeast and bacteria.
• An example is the Hepatitis B vaccine.
• A gene coding for a vaccine protein is inserted into another virus or producer cells in culture.
• When the carrier virus reproduces or the producer cell metabolizes, the vaccine protein is also created.
• This approach results in a recombinant vaccine where the immune system recognizes the expressed protein, providing future protection.
• Examples: Hepatitis B, Influenza (injection), Haemophilus influenza type b (Hib), Pertussis (as part of DTP combined immunization), Pneumococcal, and Meningococcal vaccines.

In simple words: Vaccination is giving a weakened or dead part of a germ to a person so their body can learn to fight it without getting sick. There are different types, like using live but weak germs, dead germs, only parts of germs, or modified toxins, to teach the body to make its own protection.

🎯 Exam Tip: When explaining vaccination, always define the process first, then systematically describe each vaccine type with relevant examples, highlighting the fundamental difference in their preparation.

The provided content from pages 15 and 16 consists solely of website navigation links, chapter listings, and copyright information. According to the "IGNORE AND SKIP — FOOTER / NAVIGATION" rule, these elements are to be completely ignored. As there are no actual questions located between page 15 and page 16, and all content on those pages falls under the "ignore and skip" rules, no output will be generated for this request.