Reading comprehension Home Exercise- 18 PASSAGE C

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.

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

A.      Equilibrium

B.      Self-tolerance

C.      Harmony

D.      Tolerance

7.       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?

A.      Antigen

B.      Microbe

C.      Allergen

D.      Autoimmune disease

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

A.      Through an allergic response

B.      Through blood type

C.      Through fine hairs protruding from the antigen surface

D.      Through characteristic shapes on the anti gen surface

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

A.      Prevent your offspring from infection by the chicken pox virus

B.      Distinguish between your body cells and that of the chicken pox virus

C.      Remember previous experiences with the chicken pox virus

D.      Match up and counteract non- self molecules in the form of the chicken pox virus

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

A.      An antigen is any substance that triggers an immune response

B.      The basic function of the immune system is to distinguish between self and  non- self

C.      One of the immune system’s primary functions is the allergic response

D.      The human body presents an opportune habitat for microbes

  

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

A.      The age of the twins’ tissue would be the same and, therefore , less likely to be rejected

B.      The identical twins tissue would carry the same self-markers and would therefore be less likely to be rejected

C.      The difference in the sex of the father and daughter would cause the tissue to be rejected by the daughter’s immune system

D.      The twins’ immune systems would remember the same encounters with childhood illnesses

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

A.      Elaborate interconnections

B.      Confusion of pathways

C.      Inherent perplexity

D.      Comprehensive coverage

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

A.      The immune system’s memory

B.      Immune troops eliminating intruders

C.      Bees swarming around a hive

D.      A sea of microbes

Answer:

6.       B   All the answers indicate peaceful coexistence. However, according to the fifth sentence of paragraph2, in the instance, the state is referred to as self- tolerance.

7.       C   See the last paragraph. The substances known as allergens are responsible for triggering an inappropriate immune response to ragweed pollen.

8.       D the last paragraph of the passage mentions that an antigen announces its foreignness with intricate shapes called epitomes that protrude from the surface.

9.       A   Every individual’s immune system must learn to recognize and deal with non-self molecules through experience. However, the last section of paragraph 2 mentions that the immune system is capable of choices b, c, and d

10.   B  According to paragraph 2, the ability to distinguish between self and non-self is the heart of the immune system. This topic is set up in the first paragraph and further elucidated throughout the body of the passage.

11.    The last paragraph mentions that tissues or cells form another individual may act as anti gens except in the case of identical twins whose cells carry identical self-markers.

12.   A  The context leads to the meaning: The first sentence speaks of complexity. From which we can infer an elaborate system of interconnections especially in light of the second sentence. There is no mention of confusion in the passage (choice  b.) The word perplexity means bewilderment and is unrelated to the passage (choice c). Choice d is a newspaper and TV term that is unrelated to the passage.

13.   C   in the first paragraph, the communication network of the millions of cells in the immune system is compared to bees swarming around a hive.