29
Why does the human body need more than its skin to function as a barrier to infecting pathogens?
  1. Skin works only against some types of bacteria. To prevent the entry of other pathogens, other physical or chemical barriers are needed.
  2. Skin does not provide a broad coverage against invasion of the body by any foreign particle, so it is not a very effective barrier.
  3. Pathogens could enter the body through several places that are not covered by skin that need to have a barrier to prevent infection.
  4. Skin acts only as a chemical barrier against pathogens. The body also needs physical barriers to prevent various types of infection.
30
Cell surface recognition occurs during many types of immune responses, including immediate and induced immune responses. How do natural killer cells and interferons represent one of each type of immune response (immediate and induced), and how does cell surface recognition play a role?
  1. Natural killer cells are an example of induced immune response as they attack host cells that have lost normal cell surface markers. Interferons are an example of immediate immune response as they are induced after cell surface markers on invading pathogens are recognized by host cells.
  2. Natural killer cells are an example of immediate immune response as they attack host cells that have lost normal cell surface markers. Interferons are an example of induced immune response as they are induced after cell surface markers on invading pathogens are recognized by host cells.
  3. Natural killer cells are an example of immediate immune response as they are induced after cell surface markers on invading pathogens are recognized by host cells. Interferons are an example of induced immune response as they attack host cells that have lost normal cell surface markers.
  4. Natural killer cells are an example of induced immune response as they are induced after cell surface markers on invading pathogens are recognized by host cells. Interferons are an example of immediate immune response as they attack host cells that have lost normal cell surface markers.
31
Why might different MHC I molecules between donor and recipient cells lead to rejection of a transplanted organ or tissue?
  1. The natural killer cells in the recipient will identify the MHC I molecules on transplanted organ as non-self proteins, causing lysis of transplanted cells. Other host cells will join to phagocytize the foreign cells.
  2. The neutrophils in the recipient will identify the MHC I molecules on transplanted organ as non-self proteins, causing lysis of transplanted cells. Other host cells will join to phagocytize the foreign cells.
  3. B lymphocytes in the recipient will identify the MHC I molecules on transplanted organ as non-self proteins. The foreign cells will then be engulfed and destroyed by B lymphocytes.
  4. The macrophages in the recipient will identify the MHC I molecules on transplanted organ as non-self proteins, causing lysis of transplanted cells. Other host cells will join to phagocytize the foreign cells.
32
Suppose a person was born without the ability to produce MHC I molecules. What problem would that create?
  1. A person without the ability to produce MHC I molecules would die immediately.
  2. A person without the ability to produce MHC I molecules would recognize self as non-self, resulting in autoimmune disease.
  3. The person’s immune system would not be able to distinguish self and non-self. This would make the person very vulnerable to infection.
  4. The person’s immune system would not be able to destroy foreign pathogen due to lack of hydrolytic enzymes. This would make the person very vulnerable to infection.
33
Suppose a series of genetic mutations prevented some, but not all, of the complement proteins from binding antibodies or pathogens. Would the entire complement system be compromised? Why or why not?
  1. No, because the complement system functions as a cascade, with each protein triggering the activity of the next protein in the cascade.
  2. Yes, because the complement system functions as a cascade, with each protein triggering the activity of the next protein in the cascade.
  3. Yes, because all the proteins of the complement system function independently.
  4. No, because all the proteins of the complement system function independently.
34
What is a likely reason to explain why vertebrate animals evolved an adaptive immune system rather than an innate system involving specific responses to specific pathogens?
  1. An adaptive immune system requires an immense amount of information to be stored, which allows vertebrate cells to be able to mount specific responses to every pathogen.
  2. As new pathogens evolve all the time, it is more conservative of energy and information storage to have an adaptive immune system that can respond to same pathogens in different ways.
  3. As new pathogens evolve all the time, it is more conservative of energy and information storage to have an adaptive immune system that can respond to different pathogens in a specific way.
  4. As new pathogens evolve all the time, it is more conservative of energy and information storage to have an adaptive immune system that can respond to different pathogens in a non-specific way.
35
Invertebrate animals have innate immune systems but lack adaptive immune systems. Vertebrates, including fish, amphibians, reptiles, birds, and mammals have both systems. What does this suggest about the evolution of these two immune systems?
  1. This suggests that the innate immune system evolved first. Invertebrates and vertebrates had a common ancestor, which had an innate immune system. After the two lineages diverged, the vertebrate line developed adaptive immunity, which continued to evolve in all vertebrates.
  2. This suggests that the adaptive immune system evolved first. Invertebrates and vertebrates had a common ancestor, which had an innate immune system. After the two lineages diverged, the vertebrate line developed adaptive immunity, which continued to evolve in all vertebrates.
  3. This suggests that the innate immune system evolved first. Invertebrates and vertebrates had a common ancestor, which had an adaptive immune system. After the two lineages diverged, the vertebrate line developed innate immunity, which continued to evolve in all vertebrates.
  4. This suggests that the adaptive immune system evolved first. Invertebrates and vertebrates had a common ancestor, which had an adaptive immune system. After the two lineages diverged, the vertebrate line developed innate immunity, which continued to evolve in all vertebrates.
36
What are naïve B or T cells and how do they function in cell-mediated and humoral immune responses?
  1. Naïve B and T cells are lymphocytes of the B and T types that have come into contact with pathogenic antigens. Naïve T cells produce antibodies in the humoral immune response, while naïve B cells stimulate the cell-mediated immune response.
  2. Naïve B and T cells are lymphocytes of the B and T types that normally circulate in the body at all times and have not come into contact with any pathogenic antigens. Activated T cells produce antibodies in the humoral immune response, while activated B cells stimulate the cell-mediated immune response.
  3. Naïve B and T cells are lymphocytes of the B and T types that normally circulate in the body at all times and have not come into contact with any pathogenic antigens. Activated B cells produce antibodies in the humoral immune response, while activated T cells stimulate the cell-mediated immune response.
  4. Naïve B and T cells are lymphocytes of the B and T types that have come into contact with pathogenic antigens. Naïve B cells produce antibodies in the humoral immune response, while naïve T cells stimulate the cell-mediated immune response.
37
A person given a flu vaccine in November comes down with a severe case of influenza in January. What can you conclude about the flu vaccine and cross reactivity?
  1. The flu vaccine elicited antibodies in the person’s body that were specific to a particular flu virus. Unfortunately, the flu virus that infected the person later in January was different enough for cross reactivity to occur between the virus antigens causing the infection.
  2. The flu vaccine suppresses antibodies in the person’s body that were specific to a particular flu virus. Unfortunately, the flu virus that infected the person later in January was different enough for cross reactivity to occur between the virus antigens causing the infection.
  3. The flu vaccine suppresses antibodies in the person’s body that were specific to a particular flu virus. Unfortunately, the flu virus that infected the person later in January was similar enough for cross reactivity to occur between the virus antigens causing the infection.
  4. The flu vaccine suppresses antibodies in the person’s body that were specific to a particular flu virus. Unfortunately, the flu virus that infected the person later in January was similar enough for cross reactivity to occur between the virus antigens causing the infection.
38
What function does the diversity of the variable region of an antibody help it perform?
  1. It helps in communication of antibodies with other components of immune system.
  2. It helps the antibodies to function with very low affinity and specificity.
  3. It enables many different antibodies to be made that all have different specificities of binding.
  4. It enables many different antibodies to be made that all have same specificities of binding.
39
How can you explain that the same antibodies found in an infant’s body are also present in the infant’s mother?
  1. Antibodies produced in the mother’s body are passed to the infant via passive immunity through breast milk.
  2. Antibodies produced in the mother’s body are passed to the infant via active immunity through breast milk.
  3. Antibodies produced in the mother’s body are passed to the infant via passive immunity through the placenta.
  4. Antibodies produced in the infant’s body are passed to the mother through the placenta.
40
Researchers have been working on developing methods for stimulating the human immune system to recognize foreign proteins as self proteins. Why would this research be applicable to treating allergies?
  1. In an allergy, a person’s immune system has been compromised, which causes unpleasant symptoms.
  2. In an allergy, a person’s immune system reacts to its own proteins, which causes unpleasant symptoms.
  3. In an allergy, a person’s immune system reacts to a harmless protein from the environment, which causes unpleasant symptoms.
  4. In an allergy, a person’s immune system reacts to a harmless protein from the environment, which causes pleasant symptoms.
41
A patient has just been informed that they have an autoimmune disease that attacks the salivary glands. How would you explain to the patient what is happening inside their body?
  1. The immune system is producing antibodies against their own proteins present in their salivary glands, causing the salivary glands to break down and become non-functional.
  2. The ability of the immune system to fight the antigen present in the salivary glands might have been compromised, causing the salivary glands to break down and become non-functional.
  3. The immune system might have reacted in an abnormal way to an antigen that may have entered salivary glands, causing the salivary glands to break down and become non-functional.
  4. Some pathogen might have entered the salivary glands, causing the salivary glands to break down and become non-functional.
42
An allergic response sometimes leads to a person’s death. How can you explain this?
  1. The allergen may bind to the hemoglobin, decreasing the affinity of hemoglobin for oxygen, leading to death.
  2. If a person has a very strong and fast response to an allergen, the tissues in the throat can swell so much in a very short time that the person cannot breathe and blood pressure may increase very quickly. Oxygen will not be carried to the brain and the person may die.
  3. If a person has a very strong and fast response to an allergen, the tissues in the throat can swell so much in a very short time that the person cannot breathe and blood pressure may drop very quickly. Oxygen will reach the cells at a faster rate and the person may die.
  4. If a person has a very strong and fast response to an allergen, the tissues in the throat can swell so much in a very short time that the person cannot breathe and blood pressure may drop very quickly. Oxygen will not be carried to the brain and the person may die.