Erythrocyte physiology Practice Questions
20 free Erythrocyte 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.
The primary function of erythrocytes is to:
- A Defend the body against invading infections
- B Transport oxygen and carbon dioxide
- C Regulate the process of blood clotting
- D Maintain long-term immune memory
Correct answer: Transport oxygen and carbon dioxide
Erythrocytes transport oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs. This function is mediated by hemoglobin.
Which pigment present in erythrocytes is responsible for oxygen transport?
- A Myoglobin
- B Cytochrome
- C Hemoglobin
- D Ferritin
Correct answer: Hemoglobin
Hemoglobin binds oxygen reversibly through its iron-containing heme groups. It gives erythrocytes their red color.
The normal lifespan of a human erythrocyte is approximately:
- A About 30 days
- B Roughly 60 days
- C Close to 90 days
- D 120 days
Correct answer: 120 days
Human erythrocytes survive for about 120 days in circulation. Aging cells are removed by the reticuloendothelial system.
Erythrocytes lack mitochondria primarily to:
- A Prevent oxidative damage to hemoglobin
- B Increase overall cell membrane flexibility
- C Avoid using the oxygen they carry
- D Reduce their overall cellular size
Correct answer: Avoid using the oxygen they carry
By lacking mitochondria, erythrocytes do not consume the oxygen they carry. This ensures maximal delivery of oxygen to tissues.
The biconcave shape of erythrocytes is important because it:
- A Increases hemoglobin synthesis
- B Facilitates rapid gas exchange
- C Prevents hemolysis
- D Enhances immune function
Correct answer: Facilitates rapid gas exchange
The biconcave shape increases surface area-to-volume ratio. This allows efficient diffusion of oxygen and carbon dioxide.
Which metabolic pathway supplies ATP in erythrocytes?
- A Krebs cycle
- B Oxidative phosphorylation
- C Glycolysis
- D Beta-oxidation
Correct answer: Glycolysis
Erythrocytes rely exclusively on anaerobic glycolysis for ATP production. They lack mitochondria and oxidative enzymes.
The destruction of aged erythrocytes mainly occurs in the:
- A Kidneys
- B Lungs
- C Spleen
- D Bone marrow
Correct answer: Spleen
The spleen removes old and damaged erythrocytes from circulation. Macrophages break down hemoglobin during this process.
Which component of hemoglobin binds oxygen directly?
- A Globin chain
- B Iron atom
- C Porphyrin ring
- D Carboxyl group
Correct answer: Iron atom
Oxygen binds reversibly to the ferrous iron (Fe2+) in the heme group. This binding is essential for oxygen transport.
The major form in which carbon dioxide is transported in blood by erythrocytes is:
- A Dissolved CO2
- B Carbaminohemoglobin
- C Bicarbonate ions
- D Carbonic acid
Correct answer: Bicarbonate ions
Most carbon dioxide is converted to bicarbonate within erythrocytes. This reaction is catalyzed by carbonic anhydrase.
Which enzyme in erythrocytes catalyzes the rapid conversion of CO2 to carbonic acid?
- A Catalase
- B Peroxidase
- C Carbonic anhydrase
- D Glutathione reductase
Correct answer: Carbonic anhydrase
Carbonic anhydrase accelerates the reversible conversion of CO2 to carbonic acid. This is crucial for efficient CO2 transport.
Erythropoietin primarily stimulates the production of erythrocytes in the:
- A Liver
- B Spleen
- C Bone marrow
- D Kidney cortex
Correct answer: Bone marrow
Erythropoietin acts on erythroid progenitor cells in the bone marrow. It increases red blood cell production.
Which condition results from a reduced number of erythrocytes or hemoglobin?
- A Polycythemia
- B Leukopenia
- C Anemia
- D Thrombocytosis
Correct answer: Anemia
Anemia is characterized by decreased erythrocyte count or hemoglobin concentration. This reduces oxygen-carrying capacity.
The osmotic fragility of erythrocytes refers to their:
- A Overall capacity to bind and carry oxygen
- B Resistance to hemolysis in hypotonic media
- C Deformability while squeezing through capillaries
- D Overall rate of hemoglobin synthesis and turnover
Correct answer: Resistance to hemolysis in hypotonic media
Osmotic fragility reflects how easily erythrocytes rupture in hypotonic solutions. It is increased in certain membrane disorders.
Which hemoglobin derivative is formed when carbon monoxide binds to hemoglobin?
- A Oxyhemoglobin
- B Methemoglobin
- C Carbaminohemoglobin
- D Carboxyhemoglobin
Correct answer: Carboxyhemoglobin
Carbon monoxide binds strongly to hemoglobin forming carboxyhemoglobin. This reduces oxygen delivery to tissues.
The Bohr effect describes the relationship between hemoglobin affinity for oxygen and:
- A Temperature
- B pH and CO2 levels
- C Iron concentration
- D Blood viscosity
Correct answer: pH and CO2 levels
The Bohr effect states that decreased pH or increased CO2 lowers hemoglobin’s affinity for oxygen. This promotes oxygen release in tissues.
Which abnormal hemoglobin is associated with sickle cell disease?
- A Hemoglobin A
- B Hemoglobin F
- C Hemoglobin S
- D Hemoglobin C
Correct answer: Hemoglobin S
Hemoglobin S causes erythrocytes to sickle under low oxygen conditions. This leads to hemolysis and vascular occlusion.
Reticulocytes are best described as:
- A Immature erythrocytes
- B Degenerating old erythrocytes
- C Fragmented erythrocyte debris
- D Nucleated marrow-bound precursors
Correct answer: Immature erythrocytes
Reticulocytes are immature red blood cells released from bone marrow. Their count reflects erythropoietic activity.
Which vitamin deficiency most directly impairs erythrocyte maturation?
- A Vitamin C (ascorbic acid)
- B Vitamin D (calciferol)
- C Vitamin B12
- D Vitamin K (phylloquinone)
Correct answer: Vitamin B12
Vitamin B12 is essential for DNA synthesis during erythropoiesis. Its deficiency leads to megaloblastic anemia.
Erythrocytes contribute to acid–base balance mainly by:
- A Continuously releasing lactic acid into plasma
- B Buffering hydrogen ions with hemoglobin
- C Actively excreting metabolic acids
- D Producing bicarbonate only within the plasma
Correct answer: Buffering hydrogen ions with hemoglobin
Hemoglobin acts as an important buffer by binding hydrogen ions. This helps maintain blood pH within normal limits.
Which property allows erythrocytes to pass through narrow capillaries?
- A Their exceptionally high hemoglobin content
- B Biconcave shape and membrane flexibility
- C Presence of a small central nucleus
- D Their large intracellular stores of ATP
Correct answer: Biconcave shape and membrane flexibility
Erythrocytes are highly flexible due to their membrane structure and biconcave shape. This allows them to deform and pass through capillaries.