Q1. If you have type AB blood, which of the following results would be expected?
Correct Answer: (c)
Individuals with AB blood type express both A and B antigens on their red blood cells. Therefore, their blood will agglutinate when exposed to either anti-A or anti-B antibodies.
Q2. Cells that target and kill body cells infected by viruses are
Correct Answer: (b)
Natural killer (NK) cells are part of the innate immune system and specialize in detecting and destroying virus-infected and cancerous cells without prior sensitization. They recognize altered or missing MHC-I molecules on infected cells and induce apoptosis.
Q3. Suppose that a new disease is discovered that suppresses the immune system. Which of the following would indicate that the disease specifically affects the B cells rather than the helper or cytotoxic T cells?
Correct Answer: (c)
B cells differentiate into plasma cells that secrete antibodies. A reduction in plasma cells directly indicates impaired B-cell function rather than defects in helper or cytotoxic T cells.
Q4. If you wanted to cure allergies by bioengineering an antibody that would bind and disable the antibody responsible for allergic reactions, which would you target?
Correct Answer: (c)
IgE antibodies are responsible for allergic reactions by binding to mast cells and triggering histamine release. Neutralizing IgE would therefore reduce or prevent allergic responses.
Q5. Receptors that trigger innate immune responses
Correct Answer: (c)
Innate immune receptors, such as Toll-like receptors, recognize conserved pathogen-associated molecular patterns (PAMPs) that are common to many pathogens, allowing a rapid, non-specific immune response.
Q6. The epidermis fights microbial infections by
Correct Answer: (d)
The skin acts as a first line of defense through multiple mechanisms: acidic pH inhibits microbial growth, lysozyme breaks down bacterial cell walls, and mucus traps pathogens, making all options correct.
Q7. Why do we need to be repeatedly vaccinated for influenza viruses?
Correct Answer: (b)
Influenza viruses frequently undergo antigenic variation by altering their surface proteins, allowing them to evade immune memory and necessitating repeated vaccination.
Q8. Structures on invading cells recognized by the adaptive immune system are known as
Correct Answer: (a)
Antigens are specific molecular structures, often proteins or polysaccharides, present on pathogens that are recognized by B-cell receptors, T-cell receptors, and antibodies, thereby activating the adaptive immune response.
Q9. Cytotoxic T cells are characterized by the
Correct Answer: (b)
Cytotoxic T cells express the CD8 co-receptor, which allows them to recognize antigens presented on MHC-I molecules of infected or abnormal cells and directly kill those cells.
Q10. Which one of the following acts as the “alarm signal” to activate the body’s adaptive immune system by stimulating helper T cells?
Correct Answer: (b)
Interleukin-1 is a cytokine released by macrophages and antigen-presenting cells. It functions as an alarm signal by activating helper T cells, thereby linking innate immunity to adaptive immunity.
Q11. If you wanted to design an artificial cell that could safely carry drugs inside the body, which molecule would you need to mimic to deter the immune system?
Correct Answer: (a)
MHC-I molecules signal to the immune system that a cell is ‘self.’ Mimicking MHC-I would help an artificial cell avoid immune detection and destruction, allowing safe drug delivery.
Q12. Diseases in which the person’s immune system no longer recognizes its own MHC proteins are called
Correct Answer: (b)
Autoimmune diseases occur when the immune system fails to recognize self molecules, such as MHC proteins, and mounts an immune response against the body’s own tissues.
Q13. In comparing T-cell receptors and immunoglobulins
Correct Answer: (c)
T-cell receptors and immunoglobulins share similar structural features and both achieve diversity through gene rearrangement processes such as V(D)J recombination.
Q14. Arrange the following events into the correct order after a paper cut occurs.
Correct Answer: (b)
The correct sequence is: bacteria enter the cut, injured cells release histamine to initiate inflammation, macrophages engulf invading bacteria, and finally helper T cells are activated to initiate adaptive immunity.
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