Leukocyte physiology Practice Questions
20 free Leukocyte physiology practice questions for the Physiology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which leukocyte is most abundant in normal adult peripheral blood?
- A Lymphocytes
- B Monocytes
- C Neutrophils
- D Eosinophils
Correct answer: Neutrophils
Neutrophils constitute about 60–70% of circulating leukocytes. They play a major role in innate immunity and acute inflammation.
The primary function of neutrophils is to:
- A Produce antibodies
- B Phagocytose pathogens
- C Release histamine
- D Mediate allergic reactions
Correct answer: Phagocytose pathogens
Neutrophils are professional phagocytes that ingest and destroy bacteria. They are the first responders during acute infections.
Which leukocyte is primarily responsible for antibody-mediated immunity?
- A Neutrophil granulocytes
- B B lymphocytes
- C Monocytes
- D Eosinophils
Correct answer: B lymphocytes
B lymphocytes differentiate into plasma cells that produce antibodies. This function is central to humoral immunity.
Diapedesis refers to the process by which leukocytes:
- A Engulf invading pathogens
- B Exit blood vessels
- C Destroy microbes intracellularly
- D Undergo programmed apoptosis
Correct answer: Exit blood vessels
Diapedesis is the movement of leukocytes through intact capillary walls. It allows immune cells to reach sites of infection or injury.
Which leukocyte plays a key role in defense against parasitic infections?
- A Neutrophils
- B Basophils
- C Eosinophils
- D Monocytes
Correct answer: Eosinophils
Eosinophils are particularly effective against parasitic infections. They release toxic granules that damage parasites.
The process by which leukocytes migrate toward higher concentrations of chemical signals is called:
- A Phagocytosis
- B Chemotaxis
- C Opsonization
- D Diapedesis
Correct answer: Chemotaxis
Chemotaxis directs leukocytes toward sites of infection or inflammation. It is guided by chemical mediators such as cytokines and complement fragments.
Which leukocyte is the largest in size?
- A Neutrophil
- B Lymphocyte
- C Monocyte
- D Basophil
Correct answer: Monocyte
Monocytes are the largest circulating leukocytes. They differentiate into macrophages when they enter tissues.
Basophils are most closely associated with which physiological response?
- A Phagocytosis
- B Cell-mediated immunity
- C Allergic reactions
- D Antibody production
Correct answer: Allergic reactions
Basophils release histamine and other mediators during allergic reactions. They play a role in hypersensitivity responses.
Which leukocyte type lacks cytoplasmic granules?
- A Neutrophils
- B Eosinophils
- C Basophils
- D Lymphocytes
Correct answer: Lymphocytes
Lymphocytes are classified as agranulocytes. Their cytoplasm lacks prominent granules seen in granulocytes.
Macrophages are derived from which circulating leukocyte?
- A Neutrophils
- B Lymphocytes
- C Monocytes
- D Basophils
Correct answer: Monocytes
Monocytes migrate into tissues and differentiate into macrophages. These cells play a major role in phagocytosis and antigen presentation.
Which leukocyte is primarily involved in cell-mediated immunity?
- A B lymphocytes
- B T lymphocytes
- C Eosinophils
- D Basophils
Correct answer: T lymphocytes
T lymphocytes mediate cellular immune responses. They are crucial for killing infected cells and regulating immune activity.
An increase in total leukocyte count is known as:
- A Leukopenia
- B Leukocytosis
- C Anemia
- D Thrombocytosis
Correct answer: Leukocytosis
Leukocytosis refers to an elevated white blood cell count. It often occurs during infections or inflammatory conditions.
Which leukocyte is most commonly increased in allergic conditions?
- A Neutrophils
- B Lymphocytes
- C Eosinophils
- D Monocytes
Correct answer: Eosinophils
Eosinophil counts often rise in allergic disorders. They are involved in modulating hypersensitivity reactions.
Opsonization enhances phagocytosis by:
- A Directly lysing and destroying the invading pathogens
- B Coating pathogens for easier recognition
- C Blocking leukocyte migration toward the infection site
- D Suppressing the production of protective antibodies
Correct answer: Coating pathogens for easier recognition
Opsonization coats pathogens with antibodies or complement proteins. This makes them easier for phagocytes to recognize and ingest.
Which leukocyte has a characteristic multilobed nucleus?
- A Lymphocyte
- B Monocyte
- C Neutrophil
- D Basophil
Correct answer: Neutrophil
Neutrophils possess a segmented, multilobed nucleus. This feature aids in their identification under a microscope.
Which leukocyte releases histamine and heparin?
- A Eosinophils
- B Basophils
- C Neutrophils
- D Monocytes
Correct answer: Basophils
Basophils contain granules rich in histamine and heparin. These substances contribute to inflammatory and allergic responses.
The primary role of monocytes after entering tissues is to:
- A Produce and secrete circulating antibodies
- B Differentiate into macrophages
- C Release histamine during inflammation
- D Directly kill invading tissue parasites
Correct answer: Differentiate into macrophages
Monocytes differentiate into macrophages in tissues. Macrophages perform phagocytosis and antigen presentation.
Which leukocyte count is most likely elevated during acute bacterial infections?
- A Eosinophils
- B Basophils
- C Neutrophils
- D Lymphocytes
Correct answer: Neutrophils
Neutrophils rapidly increase during acute bacterial infections. This response is known as neutrophilia.
Which leukocyte has the longest lifespan?
- A Circulating neutrophils
- B Tissue-recruited eosinophils
- C Granule-rich basophils
- D Memory lymphocytes
Correct answer: Memory lymphocytes
Memory lymphocytes can survive for years. They provide long-term immunity by responding rapidly to previously encountered antigens.
Leukopenia refers to:
- A An abnormal rise in circulating neutrophils
- B A decrease in total leukocyte count
- C An abnormal fall in circulating platelet count
- D An abnormal rise in circulating lymphocytes
Correct answer: A decrease in total leukocyte count
Leukopenia is defined as a reduction in total white blood cell count. It may increase susceptibility to infections.