101. Antihistamines, adrenaline and steroids are primarily used to
ⓐ. destroy all HIV particles from the body
ⓑ. produce permanent active immunity against allergens
ⓒ. reduce symptoms associated with allergic reactions
ⓓ. increase mast-cell release of histamine
Correct Answer: reduce symptoms associated with allergic reactions
Explanation: Antihistamines, adrenaline and steroids can be used to reduce symptoms associated with allergic reactions. Allergy involves an exaggerated immune response to an allergen and may involve the release of mediators such as histamine from mast cells. Treatment aims to reduce the physiological effects produced during the allergic response. This is different from allergy testing, in which small controlled amounts of suspected allergens may be used to identify the substance responsible for hypersensitivity.
102. A disorder develops because the immune system fails to maintain proper discrimination between self and non-self and begins attacking the body's own cells. This phenomenon is called
ⓐ. autoimmunity
ⓑ. passive immunity
ⓒ. allergy
ⓓ. vaccination
Correct Answer: autoimmunity
Explanation: Autoimmunity occurs when the immune system reacts against cells or components of the individual's own body. Normally, the immune system must distinguish self from non-self so that foreign material can be attacked without damaging normal tissues. When this discrimination fails, immune responses may be directed against self-cells. The relevant concept notes that genetic and other unknown causes may contribute to such disorders. This mechanism is fundamentally different from allergy, where the exaggerated response is directed against environmental antigens rather than self-components.
103. Which disease is specifically given as an example of an autoimmune disorder?
ⓐ. Rheumatoid arthritis
ⓑ. enteric typhoid fever
ⓒ. falciparum malaria
ⓓ. dermatophytic ringworm
Correct Answer: Rheumatoid arthritis
Explanation: Rheumatoid arthritis is the example of an autoimmune disease. In autoimmune conditions, the immune system mistakenly directs a response against the body's own cells or tissues because normal self/non-self discrimination has failed. The important concept is not simply the disease name but the mechanism that places it in the autoimmune category. Typhoid, malaria and ringworm are infectious diseases caused by pathogens, whereas rheumatoid arthritis is presented as an immune-system disorder involving self-directed reactivity.
104. Two patients show different immune abnormalities.
Patient P: exaggerated response to environmental pollen
Patient Q: immune attack against the patient's own body tissues
Which identification is correct?
ⓐ. P-autoimmunity; Q-allergy
ⓑ. P-allergy; Q-autoimmunity
ⓒ. P-immunodeficiency; Q-passive immunity
ⓓ. P-innate immunity; Q-vaccination
Correct Answer: P-allergy; Q-autoimmunity
Explanation: Patient P illustrates allergy because the immune system is reacting excessively to an environmental antigen such as pollen. Patient Q illustrates autoimmunity because the immune response is directed against the individual's own tissues. The distinction depends primarily on the target of the immune reaction. In allergy, the target is an external allergen, whereas in autoimmunity the immune system fails in self/non-self discrimination and reacts against self-components.
105. The human immune system is organised from several interacting components. Which combination best represents the categories?
ⓐ. Only skin, bones and skeletal muscles
ⓑ. lymphoid organs, tissues, cells, antibodies
ⓒ. Only RBCs, haemoglobin and plasma proteins
ⓓ. Only the thymus and circulating antibodies
Correct Answer: lymphoid organs, tissues, cells, antibodies
Explanation: The immune system is not a single organ or a single type of cell. It includes lymphoid organs, lymphoid tissues, specialised immune cells and soluble molecules such as antibodies. These components cooperate in recognising foreign material, producing immune responses and establishing immunological memory. Understanding this organisation helps explain why immune function involves both anatomical sites where lymphocytes develop or interact with antigens and circulating or tissue-based molecules that participate in defence.
106. Bone marrow and thymus are classified together as primary lymphoid organs because they are principally associated with
ⓐ. maturation of antigen-sensitive lymphocytes
ⓑ. mechanical filtration of contaminated drinking water
ⓒ. production of histamine during allergy
ⓓ. transmission of pathogens between individuals
Correct Answer: maturation of antigen-sensitive lymphocytes
Explanation: Primary lymphoid organs are the sites in which immature lymphocytes develop and differentiate into antigen-sensitive lymphocytes. Bone marrow and thymus constitute the primary lymphoid organs. Their central role is therefore connected with lymphocyte development rather than with the later interaction of mature lymphocytes with antigens in secondary lymphoid organs. This distinction provides the functional basis for separating primary and secondary lymphoid organs.
107. Which of the following is an important function of bone marrow?
ⓐ. Filtration of lymph from tissue spaces only
ⓑ. Release of allergens into the circulation
ⓒ. Transmission of HIV between individuals
ⓓ. continuous production of new blood cells
Correct Answer: continuous production of new blood cells
Explanation: Bone marrow is an important primary lymphoid organ and is the principal site where blood cells are produced. This includes the production of cells that eventually participate in immune defence. Its role connects the haematopoietic system with immunity because immune cells originate from blood-cell-forming processes. Bone marrow should therefore not be viewed simply as a structural tissue inside bones; it is a major biological site for generation of cellular components of the blood and immune system.
108. The thymus is located
ⓐ. near the heart beneath the breastbone
ⓑ. within the lumen of the small intestine
ⓒ. inside the lower-limb lymphatic vessels
ⓓ. inside the alveoli of the lungs
Correct Answer: near the heart beneath the breastbone
Explanation: The thymus is a primary lymphoid organ situated near the heart and beneath the breastbone. Its location is useful to distinguish it from other lymphoid structures such as lymph nodes distributed along lymphatic vessels or the spleen located elsewhere in the body. The thymus has an important role in the development and maturation of T lymphocytes. Therefore, its anatomical position and immunological function should be learned together rather than as unrelated facts.
109. An important age-related feature of the thymus is that it
ⓐ. undergoes marked reduction in size by puberty
ⓑ. increases continuously in size throughout adult life
ⓒ. disappears completely before birth
ⓓ. becomes the main reservoir of erythrocytes after puberty
Correct Answer: undergoes marked reduction in size by puberty
Explanation: The thymus is relatively prominent earlier in life but decreases considerably in size by the time puberty is attained. This age-related reduction is a characteristic feature. The thymus is especially important as a primary lymphoid organ providing an appropriate environment for T-lymphocyte development and maturation. Its reduction with age should not be confused with the function of the spleen, which is described as a major reservoir of erythrocytes and a filter for blood-borne microorganisms.
110. A developmental defect severely disrupts the microenvironment required for normal T-lymphocyte maturation in the thymus. Which immune-cell population would be most directly affected?
ⓐ. Erythrocytes only
ⓑ. Platelets only
ⓒ. T-cell population
ⓓ. Plasmodium sporozoites
Correct Answer: T-cell population
Explanation: The thymus provides a specialised environment required for the development and maturation of T lymphocytes. If this microenvironment is severely disrupted, normal T-cell maturation would therefore be directly impaired. This can have wide consequences because T lymphocytes participate in cell-mediated immunity and also contribute to the coordination of acquired immune responses. The thymic microenvironment is therefore directly linked with the development and maturation of T lymphocytes.
111. Which set consists only of secondary lymphoid organs?
ⓐ. Bone marrow, thymus, spleen, liver and kidney
ⓑ. Spleen, tonsils, Peyer's patches and appendix
ⓒ. Thymus, bone marrow, appendix, pancreas and stomach
ⓓ. Skin, bone marrow, thymus, heart and spleen
Correct Answer: Spleen, tonsils, Peyer's patches and appendix
Explanation: Secondary lymphoid organs include the spleen, lymph nodes, tonsils, Peyer's patches and appendix. These organs differ functionally from primary lymphoid organs such as bone marrow and thymus. After lymphocytes have developed and matured, secondary lymphoid organs provide important locations where lymphocytes encounter antigens and can proliferate into effector cells. Thus, the classification is based not merely on anatomy but on the stage and type of immune activity occurring in these organs.
112. The principal functional distinction between primary and secondary lymphoid organs is that
ⓐ. primary organs contain no immune cells, whereas secondary organs contain only erythrocytes
ⓑ. primary organs develop lymphocytes; secondary organs are major sites of antigen interaction
ⓒ. primary organs function only during infection, whereas secondary organs function only before birth
ⓓ. primary organs produce allergens, whereas secondary organs produce pathogens
Correct Answer: primary organs develop lymphocytes; secondary organs are major sites of antigen interaction
Explanation: Primary lymphoid organs such as bone marrow and thymus are associated with the development and maturation of lymphocytes into antigen-sensitive cells. Secondary lymphoid organs, including spleen and lymph nodes, provide sites where mature lymphocytes encounter antigens and participate in immune responses. Such interaction can lead to proliferation and formation of effector cells. The distinction therefore reflects the biological journey of lymphocytes from development to antigen-dependent activation.
113. A tissue sample from a secondary lymphoid organ contains large numbers of lymphocytes and phagocytes. The organ also filters microorganisms present in blood and acts as a large reservoir of erythrocytes. Which organ is being described?
ⓐ. Thymus
ⓑ. Bone marrow
ⓒ. Spleen
ⓓ. Peyer's patch
Correct Answer: Spleen
Explanation: The spleen is a secondary lymphoid organ rich in lymphocytes and phagocytic cells. One of its important immune functions is to filter blood and remove or respond to microorganisms carried through the bloodstream. In addition, the relevant concept identifies the spleen as a large reservoir of erythrocytes. These combined features make the spleen distinct from lymph nodes, which are more closely associated with filtering lymph and tissue-fluid-derived material rather than serving as a major erythrocyte reservoir.
114. If microorganisms enter the bloodstream, which secondary lymphoid organ is especially positioned to participate in their filtration?
ⓐ. Thymus
ⓑ. Bone marrow
ⓒ. Appendix only
ⓓ. Spleen
Correct Answer: Spleen
Explanation: The spleen filters blood and contains large numbers of lymphocytes and phagocytes, making it particularly important for responding to microorganisms carried in the circulation. Its function therefore reflects the type of body fluid it monitors. This helps distinguish the spleen from lymph nodes, which trap microorganisms and antigens arriving through lymph and tissue fluid. Matching the organ with the fluid it surveys is a useful way to understand the functional organisation of secondary lymphoid structures.
115. Lymph nodes are strategically located along the lymphatic system. Their important immune function is to
ⓐ. produce all RBCs in the adult human
ⓑ. store sporozoites before malaria transmission
ⓒ. release histamine as the primary function of the organ
ⓓ. trap lymph-borne antigens and activate lymphocytes
Correct Answer: trap lymph-borne antigens and activate lymphocytes
Explanation: Lymph nodes occur along the lymphatic system and act as important sites where microorganisms or antigens carried in lymph and tissue fluid can be trapped. Resident lymphocytes can then encounter these antigens, become activated and participate in an immune response. The arrangement allows the immune system to monitor material draining from tissues throughout the body. Thus, lymph nodes combine a filtering role with an immunological activation role, making them important secondary lymphoid organs.
116. A pathogen is present mainly in tissue fluid and subsequently enters lymphatic vessels rather than circulating initially in blood. Which organ is especially suited to trap its antigens as the lymph passes through the lymphatic system?
ⓐ. Thymus
ⓑ. Bone marrow
ⓒ. Lymph node
ⓓ. Adrenal gland
Correct Answer: Lymph node
Explanation: Lymph nodes are positioned along lymphatic vessels and therefore receive lymph draining from surrounding tissues. Microorganisms or antigens present in tissue fluid can enter lymph and subsequently become trapped in lymph nodes. This brings the antigen into close contact with lymphocytes present in the node and facilitates immune activation. The scenario demonstrates why the anatomical placement of lymph nodes is directly related to their defensive function.
117. Compare the spleen and lymph nodes using the following information.
| Feature | Organ P | Organ Q |
|---|
| Principal material filtered | Blood | Lymph and tissue-fluid-derived material |
| Additional characteristic | Large erythrocyte reservoir | Traps antigens that activate resident lymphocytes |
Which identification is correct?
ⓐ. P-lymph node; Q-thymus
ⓑ. P-bone marrow; Q-spleen
ⓒ. P-thymus; Q-bone marrow
ⓓ. P-spleen; Q-lymph node
Correct Answer: P-spleen; Q-lymph node
Explanation: Organ P is the spleen because it filters blood-borne microorganisms and also functions as a large reservoir of erythrocytes. Organ Q is a lymph node because lymph nodes trap microorganisms and antigens carried through lymph and tissue fluid, creating opportunities for resident lymphocytes to become activated. Both are secondary lymphoid organs, but they monitor different circulating compartments. This comparison shows how anatomical placement and fluid flow help determine the specific immune role of each organ.
118. Mucosa-associated lymphoid tissue, or MALT, is principally located in the mucosal linings of the
ⓐ. bones, joints and skeletal muscles only
ⓑ. respiratory, digestive, urogenital tracts
ⓒ. heart chambers and major arteries only
ⓓ. brain ventricles and spinal cord only
Correct Answer: respiratory, digestive, urogenital tracts
Explanation: MALT refers to lymphoid tissue associated with mucosal surfaces, particularly those lining the respiratory, digestive and urogenital tracts. These body surfaces are frequently exposed to material arriving from the external environment, including microorganisms and foreign antigens. Positioning lymphoid tissue at these sites allows immune cells to participate in surveillance and defence where exposure is common. MALT is therefore an important component of the broader secondary lymphoid system associated with mucosal protection.
119. Approximately what proportion of the lymphoid tissue in the human body is represented by MALT?
ⓐ. \(5\%\)
ⓑ. \(10\%\)
ⓒ. \(50\%\)
ⓓ. \(25\%\)
Correct Answer: \(50\%\)
Explanation: The relevant concept states that mucosa-associated lymphoid tissue constitutes approximately \(50\%\) of the lymphoid tissue in the human body. This large proportion reflects the importance of immune protection at mucosal surfaces, which are major interfaces between the internal body and the external environment. MALT is distributed along the respiratory, digestive and urogenital tracts rather than being concentrated in a single discrete organ. The value therefore highlights the extensive contribution of mucosal lymphoid tissue to human immune defence.
120. Which classification correctly groups the following structures?
P. Bone marrow
Q. Thymus
R. Spleen
S. Lymph nodes
ⓐ. P and R are primary lymphoid organs; Q and S are secondary lymphoid organs
ⓑ. Only P is a lymphoid organ
ⓒ. P, Q, R and S are all primary lymphoid organs
ⓓ. P and Q are primary lymphoid organs; R and S are secondary lymphoid organs
Correct Answer: P and Q are primary lymphoid organs; R and S are secondary lymphoid organs
Explanation: Bone marrow and thymus are primary lymphoid organs because they are associated with the development and maturation of lymphocytes. Spleen and lymph nodes are secondary lymphoid organs where mature lymphocytes can encounter antigens and participate in immune responses. The distinction reflects different stages of immune-cell biology: development occurs primarily in the first group, while antigen interaction and activation are major functions of the second group. Keeping these roles separate helps organise the anatomy of the immune system logically.
