CSS - PMS - CCE - PCS - General Science
Blood System
Which white blood cell is normally the most numerous in peripheral blood?
A. Basophil
B. Eosinophil
C. Neutrophil
D. Monocyte
Correct Answer: C
Neutrophils are usually the most abundant leukocytes in normal adult peripheral blood.
CSS - PMS - CCE - PCS - General Science
Blood System
The main intracellular storage protein for iron is:
A. Transferrin
B. Ferritin
C. Thrombin
D. Haptoglobin
Correct Answer: B
Ferritin stores iron in a soluble, readily mobilizable form inside cells.
CSS - PMS - CCE - PCS - General Science
Blood System
The protein that transports iron in blood plasma is:
A. Ferritin
B. Transferrin
C. Albumin only
D. Fibrinogen
Correct Answer: B
Transferrin is the main iron-transport protein in plasma.
CSS - PMS - CCE - PCS - General Science
Blood System
The pigment bilirubin is formed chiefly from breakdown of:
A. Globin chains only
B. Heme
C. Albumin
D. Fibrin
Correct Answer: B
Heme degradation produces biliverdin and then bilirubin.
CSS - PMS - CCE - PCS - General Science
Blood System
The iron recovered from destroyed red blood cells is mainly:
A. Always excreted in urine
B. Recycled for new hemoglobin synthesis
C. Converted into glucose
D. Stored only in platelets
Correct Answer: B
Iron is efficiently recycled, transported by transferrin, and reused in erythropoiesis or stored as ferritin.
CSS - PMS - CCE - PCS - General Science
Blood System
The breakdown of old red blood cells occurs prominently in the:
A. Spleen
B. Pancreas
C. Thyroid
D. Gallbladder
Correct Answer: A
The spleen is a major site where aged or damaged RBCs are removed by macrophages.
CSS - PMS - CCE - PCS - General Science
Blood System
Folic acid deficiency most characteristically affects:
A. DNA synthesis in rapidly dividing cells
B. Oxygen binding to heme iron directly
C. Platelet granule release
D. ABO antigen expression only
Correct Answer: A
Folate is essential for nucleotide synthesis and normal cell division, including erythroid precursors.
CSS - PMS - CCE - PCS - General Science
Blood System
Vitamin B12 deficiency can impair red blood cell formation because it disrupts:
A. DNA synthesis
B. Fibrin formation
C. Platelet adhesion
D. Plasma filtration
Correct Answer: A
Vitamin B12 is required for normal DNA synthesis; deficiency produces megaloblastic changes in rapidly dividing marrow cells.
CSS - PMS - CCE - PCS - General Science
Blood System
A deficiency of iron most directly impairs synthesis of:
A. Albumin
B. Hemoglobin
C. Fibrinogen
D. Antibodies
Correct Answer: B
Iron is an essential component of heme, so deficiency limits hemoglobin synthesis.
CSS - PMS - CCE - PCS - General Science
Blood System
2,3-BPG in red blood cells generally causes hemoglobin to:
A. Bind oxygen more tightly
B. Release oxygen more readily
C. Stop binding carbon dioxide
D. Convert into myoglobin
Correct Answer: B
2,3-BPG lowers hemoglobin's oxygen affinity and promotes oxygen unloading to tissues.
CSS - PMS - CCE - PCS - General Science
Blood System
The Bohr effect describes decreased hemoglobin affinity for oxygen when:
A. pH rises and CO2 falls
B. pH falls and CO2 rises
C. Temperature falls only
D. Blood becomes more alkaline only
Correct Answer: B
Higher CO2 and lower pH promote oxygen unloading from hemoglobin in metabolically active tissues.
CSS - PMS - CCE - PCS - General Science
Blood System
The enzyme in red blood cells that rapidly catalyzes CO2 hydration is:
A. Catalase
B. Carbonic anhydrase
C. Pepsin
D. Thrombin
Correct Answer: B
Carbonic anhydrase rapidly converts CO2 and water to carbonic acid, facilitating bicarbonate formation.
CSS - PMS - CCE - PCS - General Science
Blood System
Most carbon dioxide in blood is transported in the form of:
A. Dissolved CO2 only
B. Carbaminohemoglobin only
C. Bicarbonate ions
D. Carbon monoxide
Correct Answer: C
Most CO2 is converted to bicarbonate, especially within red blood cells, and transported in plasma.
CSS - PMS - CCE - PCS - General Science
Blood System
Carbon monoxide is dangerous because it binds to hemoglobin with:
A. Much lower affinity than oxygen
B. About the same affinity as oxygen
C. Much higher affinity than oxygen
D. No measurable affinity
Correct Answer: C
Carbon monoxide binds hemoglobin far more strongly than oxygen, reducing oxygen transport.
CSS - PMS - CCE - PCS - General Science
Blood System
Oxyhemoglobin is formed when hemoglobin combines reversibly with:
A. Carbon dioxide
B. Oxygen
C. Nitrogen
D. Bicarbonate
Correct Answer: B
Oxyhemoglobin is the reversible complex of hemoglobin with oxygen.
CSS - PMS - CCE - PCS - General Science
Blood System
One hemoglobin molecule can bind a maximum of how many oxygen molecules?
A. 1
B. 2
C. 4
D. 8
Correct Answer: C
Hemoglobin has four heme groups, and each can bind one oxygen molecule.
CSS - PMS - CCE - PCS - General Science
Blood System
The iron-containing part of hemoglobin is called:
A. Globin
B. Heme
C. Albumin
D. Porphyrin-free protein
Correct Answer: B
Each hemoglobin molecule contains heme groups with ferrous iron that bind oxygen.
CSS - PMS - CCE - PCS - General Science
Blood System
Because mature red blood cells lack mitochondria, they:
A. Cannot carry oxygen
B. Do not consume the oxygen they transport for oxidative phosphorylation
C. Cannot contain enzymes
D. Cannot enter capillaries
Correct Answer: B
Absence of mitochondria prevents RBCs from using transported oxygen for mitochondrial respiration.
CSS - PMS - CCE - PCS - General Science
Blood System
The mature human red blood cell obtains most of its ATP through:
A. Oxidative phosphorylation
B. Anaerobic glycolysis
C. Beta oxidation
D. Citric acid cycle
Correct Answer: B
Mature RBCs lack mitochondria and therefore depend largely on anaerobic glycolysis for ATP.
CSS - PMS - CCE - PCS - General Science
Blood System
The biconcave shape of a red blood cell mainly helps by:
A. Increasing surface area for gas exchange
B. Producing antibodies
C. Starting coagulation
D. Destroying pathogens
Correct Answer: A
The biconcave disc shape increases surface-area-to-volume ratio and improves deformability through capillaries.