Introduction:
Immune system is the defense system of an organism which consists of various biological processes and structures that provide protection against various pathogens. The immune system must be able to identify variety of pathogenic microbes and to differentiate them from the host’s cells.
Answer to Problem 1TYK
Correct answer:
The three lines of defenses i.e. physical barrier, innate immune system and adaptive immune system, work independently of each other in defending against a particular pathogen.
Explanation of Solution
Justification for the correct answer:
Option (a) states that ‘the three lines of defense work independently of each other in defending against a particular pathogen’. This is a true statement as each organism, which is exposed to the disease causing viruses and organisms, consists of three lines of defense against these threats. First line is physical barriers like skin, second line is innate immune system and third line of defense includes adaptive immune system. Notably, these three host defense lines take cumulative actions to defend the host against pathogenic microbes. Hence, option (a) is correct.
Justification for the incorrect answers:
Option (b) states that ‘physical barriers are part of the immune system. This statement is not true as physical barriers are not a part of immune system. The mammalian immune system of an organism is made up of innate and adaptive immunity. So, it is an incorrect option.
Option (c) states that ‘the adaptive immune system reacts faster to pathogens than the innate immune system. This is false as the innate immune responses are the first one to act when the host’s body is attacked by pathogenic microbes, whereas adaptive immunity takes several days to become protective. So, it is an incorrect option.
Option (d) states that ‘once the adaptive immune system is activated in response to a specific pathogen, the innate immune system stops functioning against that specific pathogen’. This is an incorrect statement because the innate and adaptive immunity take cumulative action against pathogens. So, it is an incorrect option.
Option (e) states that ‘white blood cells are the key participants in adaptive immunity but not in innate immunity’. This is an incorrect statement as the white blood cells are part of both innate and adaptive immune response. So, it is an incorrect option.
Hence, options (b), (c), (d) and (e) are incorrect.
Thus, it can be concluded that host defense system prevents the invasion of pathogens by the three lines of defenses i.e. physical barrier, innate immune system and adaptive immune system.
Want to see more full solutions like this?
Chapter 45 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Which of the following is a function of cytokines? A. Promote antibody invaders. B. Help T cells recognize invaders. C. Attract white blood cells to a possible invader. D. Destroy cancer cells.arrow_forwardWhich of the following statements is not correct? A. Bacterial LPS is recognized by TLR4. B. TLRs act as an alarm system to alert both the innate and adaptive immune systems that an infection is brewing. C. Cytokines released by activated macrophages increase permeability of blood vessels. D. Acute phase proteins are produced by activated macrophages. E. TNF-alpha may be released systemically.arrow_forwardExplain why each choice (a-d) is correct or incorrect. A vaccine is effective because a. The vaccine contains the antibodies necessary to fight infection. b. The vaccine contains the lymphocytes necessary to fight infection. c. The secondary response of the adaptive immunity is faster and more efficient than the primary response. d. B lymphocytes are unable to mount an immune response the first time they are exposed to a new pathogen.arrow_forward
- Antibodies against a specific antigen can be injected into a person to provide passive immunity. For which reason is this NOT as effective as the process of vaccination with that antigen? Select one: a. Injection of antibodies may cause allergic reactions, while vaccination never causes allergic reactions. b. Injection of antibodies does not provide long-lasting immunity, and vaccination with antigens triggers a clonal selection of B cells and cytotoxic T cells. c. Vaccination with antigens triggers a clonal selection of B cells and cytotoxic T cells. d. Injection of antibodies does not provide long-lasting immunity. e. Injection of antibodies does not provide long-lasting immunity and may cause allergic reactions, while vaccination never causes allergic reactions.arrow_forwardWhich of the following statements is TRUE? A. Lymphatic vessels and veins have valves B. All Lymphocytes are part of our Non-specific immune defenses C. Chicken pox vaccines involve the injection of antibodies D. Spleens are lymph nodes which drain lymph fluid back to the blood circulation What do complement proteins, inflammation and fever have in common? A. All are part of the specific defenses mechanisms of the immune system (also called adaptive immunity) B. All are processes that occur in lymph nodes C. All occur as part of the non-specific defenses D. All occur as a direct result of antigen processing in an antigen processing cellarrow_forwardReceptors that trigger innate immune responses a. are antibodies recognizing specific antigens. b. are T-cell receptors recognizing specific antigens. c. recognize pathogen-associated molecular patterns. d. are not specific at all.arrow_forward
- Which of the following is false about innate immune receptors? A. They are encoded by intact genes inherited through the germline and are deployed non-clonally. B. They include pattern recognition receptors C. They are encoded by genes assembled from individual gene segment and clonally distributed. D. They recognize foreign molecules on microbes. E. none of the abovearrow_forwardwhich of the following is true about the immune system? check all that apply. a. cd8 t cells eliminate intracellular pathogens such as viral infected cells b. cd8 t cells with the help of cd4 t cells can eliminate viral infections c. cd4 cells make cytokines to help t cells, b cells and other immune cells d. a typical infection is initially controlled by innate immunity followed by adaptive immunity and generation of memory response e. antibodies eliminate extracellular pathogens or antigens circulating in the human bodyarrow_forwardDecreased immunity is a symptom of HIV/AIDS. This is caused by which of the following? Select one: a. HIV destroys antigens. This decreases the possibility of recognizing pathogens in the future. b. HIV destroys memory T cells. If the body is infected again, there is no antibodies to fight an infection. c. HIV attacks the macrophages. Pathogens cannot be destroyed once they enter the body. d. HIV attacks the helper T cells. This allows pathogen cells to enter the body unnoticed.arrow_forward
- Which of these is a valid example of an antigen and its corresponding epitope? Select one: a. An antigen is a retrovirus and an epitope is a portion of the retrovirus to which an antibody or T-cell binds. b. An antigen is an antibody and an epitope is the cytotoxic T-cell produced to degrade the antibody. c. None of these choices. d. An antigen is a cytotoxic T-cell and an epitope is a molecular portion of foreign material. e. An antigen is an antibody and the epitope is a virus to which the antigen binds.arrow_forwardWhich of the following statements regarding CD4 is incorrect? a. MHC class II molecules present antigens to CD4 T cells. b. CD4 is the receptor used for HIV entry into CD4 T cells. c. CD4 is made up of two separate membrane-bound chains. d. Late in the progression of an HIV infection, the number of CD4 T cells in the circulation diminishes. e. CD4 is referred to as a T-cell co-receptor.arrow_forwardWhich of the following statements about T cells is false? a. Helper T cells release cytokines while cytotoxic T cells kill the infected cell. b. Helper T cells are CD4+, while cytotoxic T cells are CD8+. c. MHC II is a receptor found on most body cells, while MHC I is a receptor found on immune cells only. d. The T cell receptor is found on both CD4+ and CD8+ T cells.arrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning