Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

The immune cells and other cells in the body coexist peaceably in a state known as

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

What is the specific term for the substance capable of triggering an inappropriate or harmful immune response to a harmless substance such as ragweed pollen?

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

How do the cells in the immune system recognize an antigen as foreign or non-self?

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

After you had the chicken pox-your immune system will be able to do all of the following EXCEPT

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

Which of the following best expresses the main idea of this passage?

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

Why would tissue transplanted from father to daughter have a greater risk of being detected as foreign than a tissue transplanted between identical twins?

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

What is the meaning of the underlined word intricacies as it is used in the first sentence of the passage?

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

What is the analogy used to describe the communication network among the cells in the immune system?

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

Choose the word which is most nearly thesame in meaning to the word given in bold as used in the passage.
Intruders

Read the following passage carefully and answer the questions given below it. Certain words are given in bold in the passage to help you locate them while answering some of the questions. 

The immune system protects the body against disease or other potentially damaging foreign bodies. When functioning properly, the immune system identifies and attacks a variety of threats, including viruses, bacteria and parasites, while distinguishing them from the body’s own healthy tissue.The Lymphatic system consists of bone marrow, spleen, thymus and lymph nodes. Bone marrow produces white blood cells, or leukocytes.The spleen is the largest lymphatic organ in the body contains white blood cells that fight infection or disease.The thymus is where T-cells mature. T-cells help destroy infected or cancerous cells.Lymph nodes produce and store cells that fight infection and disease.
Lymphocytes and leukocytes are small white blood cells that play a large role in defending the body against disease.The two types of lymphocytes are B-cells, which make antibodies that attack bacteria and toxins, and T-cells, which help destroy infected or cancerous cells.Leukocytes are white blood cells that identify and eliminate pathogens.
The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communications network consisting of millions and millions of cells. Organized into sets and subsets, these cells pass information back and forth like clouds of bees swarming around a hive. The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate, effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and non-self. When immune defenders encounter cells or organisms carrying foreign or non-self molecules, the immune troops move quickly to eliminate the intruders. Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a self-marker. Rather, immune cells and other body cells coexist peaceably in a state known as self-tolerance. When a normally functioning immune system attacks a non-self molecule, the system has the ability to remember the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies passed during lactation, this so-called immune system memory is not inherited. Despite the occurrence of a virus in your family, your immune system must learn from experience with the many millions of distinctive non-self molecules in the sea of microbes in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each non-self invader.
Any substance capable of triggering an immune response is called an antigen. Antigens are not to be confused with allergens, which are most often harmless substances (such as ragweed pollen or cat hair) that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium, a fungus, a parasite, or even a portion or product of one of these organisms. Tissues or cells from another individual (except an identical twin, whose cells carry identical self markers) also act as antigens; because the immune system recognizes transplanted tissues as foreign it rejects them. The body will even reject nourishing proteins unless they are first broken down by the digestives system into their primary, non- antigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitomes, which protrude from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitomes on their surface; some may even carry several hundred. Some epitomes will be more effective than others at stimulating an immune response. Only in abnormal situations does the immune system wrongly identify self as non-self and execute a misdirected immune attack. The result can be a so-called autoimmune disease such as rheumatoid arthritis or systemic lupus erythematosus. The painful side effects of these diseases are caused by a person’s immune system actually attacking itself.

Choose the word which is opposite in meaning to the word given in bold as used in the passage.
Intricate