Innate Immunity Practice Questions
20 free Innate Immunity practice questions for the Microbiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What is innate immunity?
- A Non-specific first line of defense
- B Immunity developed after infection
- C Immunity from vaccination
- D Antibody-mediated immunity
Correct answer: Non-specific first line of defense
Innate immunity is the body's immediate, non-specific defense against pathogens. It acts as the first line of protection before adaptive immunity is activated.
Which physical barrier is part of innate immunity?
- A Skin
- B IgM
- C T cells
- D B cells
Correct answer: Skin
The skin acts as a physical barrier preventing pathogens from entering the body. It is one of the most important components of innate immunity.
Which cells are primarily responsible for phagocytosis?
- A Neutrophils and macrophages
- B Red blood cells and platelets
- C B cells and T cells
- D Mast cells and basophils
Correct answer: Neutrophils and macrophages
Neutrophils and macrophages engulf and destroy pathogens through phagocytosis. They play a central role in innate immune defense.
Which molecule is involved in inflammation?
- A Hemoglobin
- B Histamine
- C Insulin
- D Cholesterol
Correct answer: Histamine
Histamine is released during inflammation and increases blood vessel permeability. This allows immune cells to reach the site of infection.
Which cells are known as natural killer (NK) cells?
- A Phagocytic cells that clear cellular debris
- B Regulatory cells that suppress immune activity
- C Innate immune cells that kill infected cells
- D Adaptive cells that generate specific antibodies
Correct answer: Innate immune cells that kill infected cells
Natural killer cells are part of innate immunity and destroy virus-infected and tumor cells. They do not require prior sensitization.
What is the role of complement proteins?
- A Transport oxygen through blood vessels
- B Enhance phagocytosis and lyse pathogens
- C Produce antibodies in response to antigens
- D Regulate hormonal activity across tissues
Correct answer: Enhance phagocytosis and lyse pathogens
Complement proteins assist in destroying pathogens by forming membrane attack complexes and enhancing phagocytosis. They are part of innate immunity.
Which process involves engulfing pathogens?
- A Hematopoiesis
- B Phagocytosis
- C Diffusion
- D Filtration
Correct answer: Phagocytosis
Phagocytosis is the process by which immune cells ingest and destroy pathogens. It is a key function of innate immune cells.
Which chemical barrier is found in the stomach?
- A Pancreatic enzymes
- B Hydrochloric acid
- C Secretory antibodies
- D Steroid hormones
Correct answer: Hydrochloric acid
Hydrochloric acid in the stomach kills many ingested pathogens. It serves as an important chemical barrier in innate immunity.
What is inflammation?
- A Decrease in blood flow to injured tissues
- B Protective response to injury or infection
- C Production of antibodies against pathogens
- D Destruction of red blood cells in the spleen
Correct answer: Protective response to injury or infection
Inflammation is a protective response involving redness, heat, swelling, and pain. It helps eliminate pathogens and initiate healing.
Which cells release cytokines during immune response?
- A Red blood cells
- B White blood cells
- C Smooth muscle cells
- D Epithelial cells
Correct answer: White blood cells
White blood cells release cytokines, which are signaling molecules that regulate immune responses. They help coordinate defense mechanisms.
Which type of receptor on innate immune cells detects conserved microbial structures?
- A T-cell antigen receptor
- B B-cell antigen receptor
- C Pattern recognition receptor
- D Fc receptor for immunoglobulin
Correct answer: Pattern recognition receptor
Pattern recognition receptors (PRRs) detect conserved microbial structures known as pathogen-associated molecular patterns (PAMPs). This recognition triggers innate immune responses.
Which type of immunity does not have memory?
- A Adaptive immunity
- B Herd immunity
- C Cell-mediated immunity
- D Innate immunity
Correct answer: Innate immunity
Innate immunity does not develop memory and responds the same way to repeated infections. It provides immediate defense.
Which substance traps pathogens on the linings of the respiratory and digestive tracts?
- A Bile
- B Sebum
- C Lysozyme
- D Mucus
Correct answer: Mucus
Mucus traps pathogens on mucosal surfaces like the respiratory tract. It helps prevent microbes from entering deeper tissues.
Which cells are the first responders to infection?
- A B cells
- B T cells
- C Plasma cells
- D Neutrophils
Correct answer: Neutrophils
Neutrophils are rapidly recruited to infection sites. They are among the first cells to respond and perform phagocytosis.
Which protein inhibits viral replication?
- A Insulin
- B Hemoglobin
- C Albumin
- D Interferon
Correct answer: Interferon
Interferons are proteins that inhibit viral replication. They are produced by infected cells as part of innate immunity.
Which of the following is a mechanical barrier?
- A Tears
- B Antibodies
- C Cytokines
- D Bile
Correct answer: Tears
Tears help wash away pathogens from the eyes. They also contain antimicrobial substances like lysozyme.
Which enzyme in saliva helps destroy bacteria?
- A Amylase
- B Protease
- C Lipase
- D Lysozyme
Correct answer: Lysozyme
Lysozyme breaks down bacterial cell walls. It is present in saliva, tears, and other secretions.
Dendritic cells, macrophages, and B cells belong to which functional group of immune cells?
- A Regulatory T cells
- B Cytotoxic killer cells
- C Immunoglobulin-secreting cells
- D Antigen-presenting cells
Correct answer: Antigen-presenting cells
Antigen-presenting cells, such as macrophages and dendritic cells, process and present antigens. This bridges innate and adaptive immunity.
Which process increases blood flow to infected tissues?
- A Vasoconstriction
- B Filtration
- C Vasodilation
- D Diffusion
Correct answer: Vasodilation
Vasodilation increases blood flow, bringing immune cells to the infection site. It is a key feature of inflammation.
Which innate immune component forms pores in pathogen membranes?
- A Secreted antibodies
- B Steroid hormones
- C Complement system
- D Digestive enzymes
Correct answer: Complement system
The complement system can form membrane attack complexes that create pores in pathogens. This leads to cell lysis and death.