RBSE Solutions for Class 12 Biology Chapter 39 Immune System

Rajasthan Board RBSE 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

Question 2.
Antigen is –
(a) sugar
(b) Aromatic
(c) Nucleic acid
(d) Protein
Answer:
(d) Protein

Question 3.
Which antibody is involved in hypersensitivity/allergic reaction?
(a) IgG
(b) IgA
(c) IgE
(d) IgM
Answer:
(c) IgE

Question 4.
Which antibody is transmitted from mother placenta to embryo?
(a) IgG
(b) IgA
(c) IgE
(d) IgM
Answer:
(a) IgG

Question 5.
What is produces in the body by vaccination?
(a) Plasma
(b) Histamine
(c) Antibody
(d) Toxoid
Answer:
(c) Antibody

RBSE Class 12 Biology Chapter 39 Very Short Answer Type Questions

Question 1.
Which part of antigen binds with an antibody?
Answer:
Fab (Fragment antigen binding).

Question 2.
How many types of antigen and antibody are found?
Answer:
Five types.

Question 3.
Which is the most abundantly found antibody?
Answer:
Immunoglobulin (IgG).

Question 4.
Which kind of response is responsible to destroy tumour?
Answer:
Monoclonal antibodies (MAB), cell-mediated immunity.

Question 5.
Name some vaccine which is made up of Killed or inactivated pathogens.
Answer:
Polio injection, Hepatitis Rabies, Cholera, Typhoid etc.

Question 6.
Who is known as the father of Immunology?
Answer:
Edward Jenner

RBSE Class 12 Biology Chapter 39 Short Answer Type Questions

Question 1.
Write the definition of Immunity.
Answer:
Immunity and Immunology:
“The resistance acquired by the body to fight against diseases or microorganisms or toxic product is called Immunity. Term Immunity originated from Latin word Immunis which means free of burden [Capability to protect from infectious factor]. The branch of science which deals with the study of immunity is called Immunology.

It deals with the study of various component of the Immune system and their functions. It provides immunity against organisms. Our body has the capacity to distinguish between body cells (“self”) and foreign materials (“non-self”). It will react to foreign materials with an immune response that eliminates the intruding material from the body.

Question 2.
Name the main physiological barrier.
Answer:
Many physiological activities in the body prevent the entry of the germs into the body. Some of them are as follows:

Fever: The invading germs secrete different types of toxins. As a result, the number of WBC is increased to destroy them. In addition, macrophages are also increased which secrete pyrogens. These pyrogens increase body temperature which inhibits bacterial growth.
Lysozyme: The body secretions such as tears, saliva, sweat etc. are increased as a result of infection. These secretions contain an enzyme lysozyme which kills the
germs by digesting their cell wall.
The stomach secretes dilute HCl which makes the pH strongly acidic (pH 1 to 2). It acts as a strong germicidal.
There is the release of bile juice into the duodenum which also acts as germicidal.
The mucus secreted in the respiratory passage acts as a barrier for germs.
The cerumin found in the sebum secreted by the sebaceous glands of the skin also kills germs.

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 into 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.

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 foetus. IgA antibodies are transferred from mother to child in the form of colostrum.

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

It develops in the blood. The lymphocytes from various globulin proteins to destroy the different antigens.
These lymphocytes are formed from the mesodermal stem cells but some lymphocytes are also formed in the thymus gland & bone marrow.
In humoral immunity when an antigen! bacteria/virus enters into the body, the lymphocytes in lymphatic organs divide rapidly and convert into plasma cells to form required antibodies.
It protects the body from tetanus, cold, smallpox, measles, cholera etc.

Question 5.
Write a note on T cell.
Answer:
D – Q1 (B)

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 is based on the activity of two types of lymphocytes viz., B-cells & T-cells. Bone marrow produces the precursor cells of both B & T lymphocytes.

1. B-Lymphocytes:

They originate from the stem cells of the bone marrow.
The B-lymphocytes may mature in the liver (embryonic stage) and in the bone marrow (Adults) in mammals.
In the embryonic Chick, the maturation occurs in an organ called bursa of Fabricius (present in the dorsal wall of the proctodaeum, hence the name-lymphocyte is given.
The B-lymphocytes colonizes in the lymph nodes, spleen, tonsils, adenoid and other tissues of the lymphatic system.
The B-cells synthesize antibodies, causing agglutination of unwanted antigens.
Some B-cells enlarge and divide into a clone of plasma cells under the influence of thymic hormone.
The plasma cells start secreting antibodies into the blood circulation. The activated B-cells which do not differentiate into plasma cells remain as memory B cells.
These cells are ready to respond more rapidly and forcefully than initially when the same antigen challenges the body in the future.

2. T-lymphocytes

T-cells carry out cellular immune responses. The T-cells migrate out of the bone marrow and mature in a special organ-like thymus.
These T-cells leave the thymus and travel to secondary lymphoid organs like lymph nodes, tonsils and spleen. In these organs, they can be activated to produce antibodies or T-cells receptors.
These cells then pass to the blood system and back again to the lymph.
When a T-cell recognizes an antigen, it multiplies and differentiates into a killer or cytotoxic T-cells, Helper T cells and suppressor T-cells.
Killer T-cells or N.K. cells (Natural K. cells) destroy their target cells by releasing substances that dissolve & hole in its plasma membrane, causing the target cells to lyse.
These substances are proteins called perforins that punch large round holes in the plasmalemma of the attacked cells.
Helper T-cells are most common and are 75% of total T-lymphocytes. These cells stimulate B-cells to make antibodies and facilitate the action of other T-cells.
Some helper T-cells secrete lymphokines which are messenger molecules that recruit other WBCs to the battle site.
The important lymphokines secreted by the helper T-cells are as follows:
- Interleukin
- Granulocyte – monocyte colony-stimulating factor
- Interferon (anti-viral substance)
Helpers T-Cells are also called as T4 or HT cells. Some helper T-cells rush towards spleen and lymph nodes, where they alert the B-cells.
Suppressor T-cells (ST-Cells) or the peacemaker cells protect the body’s own cells from attack, called immune tolerance.
Suppressor T-cells along with helper T-cells are called regulatory T-cells.
ST-cells release substances that switch off B-cells and they order killer T-cells to stop the fight. Phagocytes in this peace interval now move around the area, removing cell-debris and dead cells and damaged tissues.
Some of the ST-cells become Memory T-Cells which are stored in the spleen & lymph nodes. They recognize original invading antigens, ever years after infection.
In addition, there are amplifier T-cells which help Tcells, ST-cells & B-cells to increase levels of activities.
Macrophages are special phagocytes which play significant roles in the body defence.
They eat anything suspicious in the blood, tissues and the lymph system, also cleanse dust & smoke in the lungs.
They secrete interleukin-1 that stimulates secretion of interleukin-2 by helper T-cells & induces proliferation of B-cells.

Question 2.
Define the immune system and also explain its types.
Answer:
Immunity and Immunology:

“The resistance acquired by the body to fight against diseases or microorganisms or toxic product is called Immunity. Term Immunity originated from Latin word Immunis which means free of burden [Capability to protect from infectious factor).
The branch of science which deals with the study of immunity is called Immunology.
It deals with the study of various component of the Immune system and their functions. It provides immunity against organisms.
Our body has the capacity to distinguish between body cells (“self”) and foreign materials (“non-self”). It will react to foreign materials with an immune response that eliminates the intruding material from the body.

Types of Immunity:
In broad terms, immunity is of two types viz –

Natural or Innate Immunity
Acquired Immunity

1. Natural or Innate Immunity:

This Immunity is inborn i.e. it exists since birth.
It is independent of previous experience.

There are four types of innate protective measures against invading germs:

Anatomical barriers
Physiological barriers
Phagocytic or cellular barriers
Inflammatory barriers.

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Physical Barrier:
It prevents the entry of disease-causing agents into the body. This is the first line of defence in the body. The following organs are involved in it:
1. Skin:

It is the first line of defence.
Its outer layers of the epidermis are dead due to deposition of Keratin protein and it forms a barrier layer. The germs can’t penetrate this layer.
The dermis has many sebaceous glands which secrete an oily secretion called Sebum.
Sebum has lactic acid and fatty acid which maintain the pH of skin in between 3 to 5.
Most of the microorganisms do not survive in this pH.
Most of the bacteria also do not grow in this pH.

2. Mucous Membrane:

Many body organs such as, Respiratory system, digestive system and reproductive system having a layer of epithelium cells which are covered with a protective layer of mucus.
If the germ falls on this path, then they get destroyed in the protective mucus layer. It thus restricts the entry of such agents which may otherwise prove to be infectious.
The mucous membrane also having an enzyme called lysozyme which acts as germicidal.

Physiological Barriers:
Many physiological activities in the body prevent the entry of the germs into the body. Some of them are as follows:

Fever: The invading germs secrete different types of toxins. As a result, the number of WBC is increased to destroy them.
In addition, macrophages are also increased which secrete pyrogens. These pyrogens increase body temperature which inhibits bacterial growth.
Lysozyme: The body secretions such as tears, saliva, sweat etc. are increased as a result of infection. These secretions contain an enzyme lysozyme which kills the germs by digesting their cell wall.
The stomach secretes dilute HC1 which makes the pH strongly acidic (pH 1 to 2). It acts as a strong germicidal.
There is a release of bile juice into the duodenum which also acts as germicidal.
The mucus secreted in the respiratory passage acts as a barrier for germs.
The cerumin found in the sebum secreted by the sebaceous glands of the skin also kills germs.

Cellular Phagocytic Barrier:
It is an important technique of Innate Immunity. It involves some special cells which destroy the germs by phagocytosis. It was discovered by E. Metchnikoff. These phagocytic cells are as follows:
1. Leucocytes or WBC:

Any infection in the body results in Leucocytosis (Increased number of WBC). The neutrophil WBC destroy the germs by phagocytosis The neutrophils have phagocytic and lactoferrin which are antibacterial.
The monocyte WBC also destroy the germs by phagocytosis.
The Lymphocyte WBC are of two types – B & T lymphocytes. Thy destroys the germs by forming antibodies.

2. Macrophages:

They are modified monocytes which perform phagocytosis.
The macrophages found in the blood stimulate the formation of an antigen-antibody complex.
They have a large amount of lysozyme enzyme.

Inflammatory barrier/Cytokine Barrier:

Inflammation is an important defence mechanism of the host to prevent infection. It is induced in response to tissue damage caused by microorganism, toxins or by mechanical means.
The main aim of inflammation is to prevent the spreading of injected microorganism or toxin from the site of infection and kill them on spot by phagocytosis.
In this mechanism mast cell of connective tissue and basophils of WBC secrets a chemical indicator in the form of Histamine and Prostaglandin.
Through its secretion maks the blood cell more permeable. Plasma and phagocytes come out from the cell and function accordingly.
Serum also has a potential to destroy bacteria.

Acquired Immunity:

This immunity does not exist since birth but it is gained after birth based on the memory of the body. Hence, it is called acquired immunity.
This Immunity is obtained either from the development of antibodies in response to exposure to an antigen, as from vaccination or an attack of infectious disease, or from the transmission of antibodies, as from mother to foetus through the placenta or the injection of antiserum.
It provides third line defence to the body.
It is highly specific for an antigen. When an antigen, first time enters into the body, our immunity system makes a specific antibody against it which is called Primary Response.
In this response memory, cells are formed. When the immune system encounters a specific foreign agent, (e.g., a microbe) for the first time, it generates an immune response and eliminates the invader. This is called the first encounter.
The immune system retains the memory of the first encounter. As a result, a second encounter occurs more quickly and abundantly than the first encounter. It is called Secondary Response.

It is of two types:

Active Immunity
Passive Immunity

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1. Active Immunity:

It develops in the blood when an antigen or germ enters into 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 foetus.
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.

Question 3.
Define vaccination and explain their types.
Answer:
Vaccination:

Vaccination is a biotechnique.
The first vaccine was prepared by Edward Jenner, 1798.
He prepared a vaccine for smallpox. A cow is called as Vaca in Latin.
A cow was used in the preparation of the first vaccine. Hence, the term “Vaccine” was coined.
In this technique, the cause (germs) of the specific disease are injected in dead state/living but weakened state to produce antibodies in the body against the specific disease.
The vaccine provides Active acquired immunity to a particular disease.
Jenner took fluid from a cowpox blister and scratched it into the skin of James Fipps, an eight-year-old boy.
Inner is known as the Father of vaccination for this contribution.

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Types of Vaccine:
The vaccines are of following types:
1. Live or Attenuated Vaccines:

Attenuated vaccines can be made in several different ways. Some of the most common methods involve is passing the pathogen virus through a series of cell cultures or animal embryos (typically chick embryos).
The virus is grown in different embryos in a series. With each passage, the virus loses its ability to replicate in human cells.
Example: Measles, Mumps, Rubella, Influenza (nasal spray), Rotavirus, Oral polio. (OPV).

2. Killer or Inactivated Vaccines:

One alternative to attenuated vaccines is a killed or inactivated vaccine. Vaccines of this type are created by inactivating a pathogen, typically using heat or chemical such as formaldehyde or formalin, Phosphine etc.
This destroys the pathogen’s ability to replicate but keeps it “intact” so that the immune system can still recognize it.
Example: Polio injection (IPV), Hepatitis A, Rabies, Typhoid, Diarrhoea Rabbies.

3. Toxoid Vaccine:

Some diseases are not directly caused by a bacterium itself, but by a toxin produced by the bacterium such as Tetanus.
Its symptoms are not caused by the Clostridium tetani bacterium, but by a neurotoxin it produces (tetanospasmin).
Immunizations for this type of pathogen can be made by inactivating the toxin that causes disease symptoms.
Example: Tetanus Diptheria.
Immunizations created using inactivated toxins are called toxoids.

4. Conjugate Vaccines or Subunit Vaccine:

Conjugate vaccines contain only pieces of the pathogens they protect against.
Subunit vaccines use only part of a target pathogen to provoke a response of the immune system.
This may be done by isolating a specific protein from a pathogen and presenting it as an antigen on its own.
Example: Pertussis vaccine and Influenza vaccine.

5. Engineered Vaccine or Recombinant Vaccine:

These Vaccines are made at large scale by genetic engineering technique. They are made with the help of Yeast and Bacteria.
Example: Hepatitis.
A gene coding for a vaccine protein is inserted into another virus, or into producer cells in culture.
When the carrier virus reproduces, or when the producer cell metabolizes, the vaccine protein is also created.
The end result of this approach is a recombinant vaccine: The immune system will recognize the expressed protein and provide future protection against the target virus.
Example: Hepatitis B, Influenza (injection), Haemophilus influenza type b (Hib), Pertussis (part of DTP combined immunization), Pneumococcal, Meningococcal.