Normal cell:- 1. Normal cells show the property of contact inhibition. Therefore, when these cells come into contact with other cells, they stop dividing. 2. They undergo differentiation after attaining a specific growth. 3. These cells remain confined at a particular location. Cancerous cell:- 1. CRead more
Normal cell:-
1. Normal cells show the property of contact inhibition. Therefore, when these cells come into contact with other cells, they stop dividing.
2. They undergo differentiation after attaining a specific growth.
3. These cells remain confined at a particular location.
Cancerous cell:-
1. Cancerous cells lack the property of contact inhibition. Therefore, they continue to divide, thereby forming a mass of cells or tumour.
2. They do not undergo differentiation.
3. These cells do not remain confined at a particular location. They move into neighbouring tissues and disturb its function.
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV) via sexual or blood-blood contact. After entering the human body, the HIV virus attacks and enters the macrophages. Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse tRead more
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV) via sexual or blood-blood contact. After entering the human body, the HIV virus attacks and enters the macrophages. Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse transcriptase and gives rise to viral DNA. Then, this viral DNA incorporates into the host DNA and directs the synthesis of virus particles. At the same time, HIV enters helper T- lymphocytes. It replicates and produces viral progeny there. These newly formed progeny viruses get released into the blood, attacking other healthy helper Tlymphocytes in the body. As a result, the number of T-lymphocytes in the body of an infected person decreases progressively, thereby decreasing the immunity of a person.
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV). It has the following modes of transmission: 1. Unprotected sexual contact with an infected person. 2. Transfusion of blood from a healthy to an infected person. 3. Sharing infected needles and syringes. 4Read more
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV).
It has the following modes of transmission:
1. Unprotected sexual contact with an infected person.
2. Transfusion of blood from a healthy to an infected person.
3. Sharing infected needles and syringes.
4. From an infected mother to a child through the placenta.
(a) Innate and acquired immunity:- Innate immunity:- 1. It is a non−pathogen specific type of defense mechanism. 2. It is inherited from parents and protects the individual since birth. 3. It operates by providing barriers against the entry of foreign infectious agents. 4. It does not have a specifiRead more
(a) Innate and acquired immunity:-
Innate immunity:-
1. It is a non−pathogen specific type of defense mechanism.
2. It is inherited from parents and protects the individual since birth.
3. It operates by providing barriers against the entry of foreign infectious agents.
4. It does not have a specific memory.
Acquired immunity:-
1. It is a pathogen specific type of defense mechanism.
2. It is acquired after the birth of an individual.
3. It operates by producing primary and secondary responses, which are mediated by B−lymphocytes and Tlymphocytes.
4. It is characterized by an immunological memory.
(b) Active and passive immunity:-
Active immunity:-
1. It is a type of acquired immunity in which the body produces its own antibodies against disease causing antigens.
2. It has a long lasting effect.
3. It is slow. It takes time in producing antibodies and giving responses.
4. Injecting microbes through vaccination inside the body is an example of active immunity.
Passive immunity:-
1. It is a type of acquired immunity in which readymade antibodies are transferred from one individual to another.
2. It does not have long lasting effect.
3. It is fast. It provides immediate relief.
4. Transfer of antibodies present in the mother’s milk to the infant is an example of passive immunity.
(a) MALT- Mucosa-Associated Lymphoid Tissue (b) CMI- Cell-Mediated Immunity (c) AIDS- Acquired Immuno Deficiency Syndrome (d) NACO- National AIDS Control Organization (e) HIV- Human Immuno Deficiency virus For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-12/biolRead more
(a) MALT- Mucosa-Associated Lymphoid Tissue
(b) CMI- Cell-Mediated Immunity
(c) AIDS- Acquired Immuno Deficiency Syndrome
(d) NACO- National AIDS Control Organization
(e) HIV- Human Immuno Deficiency virus
How is a cancerous cell different from a normal cell?
Normal cell:- 1. Normal cells show the property of contact inhibition. Therefore, when these cells come into contact with other cells, they stop dividing. 2. They undergo differentiation after attaining a specific growth. 3. These cells remain confined at a particular location. Cancerous cell:- 1. CRead more
Normal cell:-
1. Normal cells show the property of contact inhibition. Therefore, when these cells come into contact with other cells, they stop dividing.
2. They undergo differentiation after attaining a specific growth.
3. These cells remain confined at a particular location.
Cancerous cell:-
1. Cancerous cells lack the property of contact inhibition. Therefore, they continue to divide, thereby forming a mass of cells or tumour.
2. They do not undergo differentiation.
3. These cells do not remain confined at a particular location. They move into neighbouring tissues and disturb its function.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-8/
What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV) via sexual or blood-blood contact. After entering the human body, the HIV virus attacks and enters the macrophages. Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse tRead more
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV) via sexual or blood-blood contact. After entering the human body, the HIV virus attacks and enters the macrophages. Inside the macrophages, the RNA of the virus replicates with the help of enzyme reverse transcriptase and gives rise to viral DNA. Then, this viral DNA incorporates into the host DNA and directs the synthesis of virus particles. At the same time, HIV enters helper T- lymphocytes. It replicates and produces viral progeny there. These newly formed progeny viruses get released into the blood, attacking other healthy helper Tlymphocytes in the body. As a result, the number of T-lymphocytes in the body of an infected person decreases progressively, thereby decreasing the immunity of a person.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-8/
What are the various routes by which transmission of human immunodeficiency virus takes place?
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV). It has the following modes of transmission: 1. Unprotected sexual contact with an infected person. 2. Transfusion of blood from a healthy to an infected person. 3. Sharing infected needles and syringes. 4Read more
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV).
It has the following modes of transmission:
1. Unprotected sexual contact with an infected person.
2. Transfusion of blood from a healthy to an infected person.
3. Sharing infected needles and syringes.
4. From an infected mother to a child through the placenta.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-8/
Differentiate the following and give examples of each: (a) Innate and acquired immunity (b) Active and passive immunity
(a) Innate and acquired immunity:- Innate immunity:- 1. It is a non−pathogen specific type of defense mechanism. 2. It is inherited from parents and protects the individual since birth. 3. It operates by providing barriers against the entry of foreign infectious agents. 4. It does not have a specifiRead more
(a) Innate and acquired immunity:-
Innate immunity:-
1. It is a non−pathogen specific type of defense mechanism.
2. It is inherited from parents and protects the individual since birth.
3. It operates by providing barriers against the entry of foreign infectious agents.
4. It does not have a specific memory.
Acquired immunity:-
1. It is a pathogen specific type of defense mechanism.
2. It is acquired after the birth of an individual.
3. It operates by producing primary and secondary responses, which are mediated by B−lymphocytes and Tlymphocytes.
4. It is characterized by an immunological memory.
(b) Active and passive immunity:-
Active immunity:-
1. It is a type of acquired immunity in which the body produces its own antibodies against disease causing antigens.
2. It has a long lasting effect.
3. It is slow. It takes time in producing antibodies and giving responses.
4. Injecting microbes through vaccination inside the body is an example of active immunity.
Passive immunity:-
1. It is a type of acquired immunity in which readymade antibodies are transferred from one individual to another.
2. It does not have long lasting effect.
3. It is fast. It provides immediate relief.
4. Transfer of antibodies present in the mother’s milk to the infant is an example of passive immunity.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-8/
The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (a) MALT (b) CMI (c) AIDS (d) NACO (e) HIV
(a) MALT- Mucosa-Associated Lymphoid Tissue (b) CMI- Cell-Mediated Immunity (c) AIDS- Acquired Immuno Deficiency Syndrome (d) NACO- National AIDS Control Organization (e) HIV- Human Immuno Deficiency virus For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-12/biolRead more
(a) MALT- Mucosa-Associated Lymphoid Tissue
(b) CMI- Cell-Mediated Immunity
(c) AIDS- Acquired Immuno Deficiency Syndrome
(d) NACO- National AIDS Control Organization
(e) HIV- Human Immuno Deficiency virus
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-12/biology/chapter-8/