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Q1. The blood vessels that carry blood away from the heart are called:
Arteries are blood vessels that carry blood away from the heart to various organs and tissues. They usually carry oxygenated blood (except the pulmonary artery). Veins carry blood toward the heart, capillaries connect arteries and veins, and venules are small veins. Arteries are the correct answer.
Q2. Which of the following blood vessels has the thinnest wall, allowing exchange of materials?
Capillaries have the thinnest walls—just a single layer of cells (endothelium). This thinness allows for the efficient exchange of oxygen, carbon dioxide, nutrients, and waste products between blood and tissues. Arteries and veins have thicker, more muscular walls, and arterioles are small arteries.
Q3. The two upper chambers of the human heart are called:
The two upper chambers of the heart are the atria (singular: atrium), also called auricles. They receive blood from the body (right atrium) or from the lungs (left atrium). The lower chambers are ventricles, the septum is the wall dividing the heart, and valves control blood flow.
Q4. The two lower chambers of the human heart that pump blood out are called:
The two lower chambers of the heart are the ventricles. They pump blood out of the heart—the right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the rest of the body. Atria receive blood, and the pericardium is the protective sac around the heart.
Q5. The valve present between the right atrium and right ventricle is called:
The tricuspid valve is located between the right atrium and the right ventricle. It prevents backflow of blood when the ventricle contracts. The bicuspid (mitral) valve is on the left side, and semilunar valves are at the exits of the ventricles. The tricuspid valve is the correct answer.
Q6. The largest artery in the human body is:
The aorta is the largest artery in the human body. It carries oxygenated blood from the left ventricle to all parts of the body. The pulmonary artery carries blood to the lungs, the carotid artery supplies the head, and the coronary artery supplies the heart muscle.
Q7. Which blood vessel carries deoxygenated blood from the heart to the lungs?
The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for oxygenation. It is the only artery that carries deoxygenated blood. The pulmonary vein carries oxygenated blood from the lungs to the heart, the aorta carries oxygenated blood to the body, and the vena cava carries deoxygenated blood to the heart.
Q8. Which blood vessel carries oxygenated blood from the lungs to the heart?
The pulmonary vein carries oxygenated blood from the lungs to the left atrium of the heart. It is the only vein that carries oxygenated blood. The pulmonary artery carries deoxygenated blood to the lungs, the aorta carries oxygenated blood to the body, and the superior vena cava carries deoxygenated blood from the upper body to the heart.
Q9. The blood vessel that carries deoxygenated blood from the upper part of the body to the right atrium is:
The superior vena cava carries deoxygenated blood from the upper part of the body (head, neck, arms) to the right atrium. The inferior vena cava carries blood from the lower part of the body. The pulmonary vein carries oxygenated blood, and the aorta carries blood away from the heart.
Q10. The muscular wall that separates the left and right sides of the heart is called:
The septum is the muscular wall that divides the heart into left and right sides, preventing mixing of oxygenated and deoxygenated blood. The pericardium is the outer protective sac, valves control blood flow, and the myocardium is the heart muscle tissue.
Q11. The approximate weight of an adult human heart is:
The average weight of an adult human heart is about 200-300 grams (roughly the size of a fist). It varies slightly between individuals based on body size and sex. The other options are either too light or too heavy.
Q12. How much blood does the human heart pump in 24 hours?
The human heart pumps about 7,200 liters of blood in 24 hours. This is calculated from the average cardiac output of about 5 liters per minute. The other options are incorrect. This pumping is essential for delivering oxygen and nutrients throughout the body.
Q13. The primary function of red blood cells (RBCs) is:
Red blood cells (RBCs) contain hemoglobin, a protein that binds to oxygen in the lungs and transports it to all body tissues. White blood cells fight infection, platelets clot blood, and antibodies are produced by white blood cells. Transporting oxygen is the main job of RBCs.
Q14. The pigment present in red blood cells that gives blood its red color is:
Hemoglobin is the red pigment in red blood cells that gives blood its color. It contains iron, which binds to oxygen. Hemocyanin is found in some invertebrates, chlorophyll is for photosynthesis, and myoglobin stores oxygen in muscles. Hemoglobin is the correct answer.
Q15. The main function of white blood cells (WBCs) is:
White blood cells are part of the immune system. Their main function is to fight infection by destroying pathogens (bacteria, viruses) and providing immunity. Red blood cells carry oxygen, platelets clot blood, and plasma transports nutrients.
Q16. The function of platelets is:
Platelets are small cell fragments that help in blood clotting. When a blood vessel is injured, platelets gather at the site and release chemicals that initiate the clotting process. Red blood cells carry oxygen, white blood cells produce antibodies, and plasma transports hormones.
Q17. Which of the following statements about insect blood (e.g., cockroach) is correct?
Insect blood (hemolymph) is colorless because it does not contain hemoglobin or red blood cells. It transports nutrients and waste but does not carry oxygen the way human blood does. Insects get oxygen directly through tracheae. Human blood is red due to hemoglobin.
Q18. Which of the following is a correct difference between arteries and veins?
Arteries carry blood away from the heart, and veins carry blood toward the heart. Veins have valves (to prevent backflow), arteries have thick walls, and the pulmonary artery carries deoxygenated blood while the pulmonary vein carries oxygenated blood.
Q19. Which scientist is credited with the discovery of blood circulation?
William Harvey is credited with the discovery of blood circulation in 1628. He described how blood is pumped by the heart and circulates through the body in a closed system. Louis Pasteur worked on germs, Hooke discovered cells, and Leeuwenhoek improved microscopy.
Q20. The blood vessel that carries deoxygenated blood from the right ventricle to the lungs is called:
The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for oxygenation. It is the only artery that carries deoxygenated blood. The pulmonary vein carries oxygenated blood from lungs to heart, the aorta carries blood to the body, and the coronary artery supplies the heart muscle.
Q21. The blood vessel that carries oxygenated blood from the lungs to the left atrium is called:
The pulmonary vein carries oxygenated blood from the lungs to the left atrium. It is the only vein that carries oxygenated blood. The pulmonary artery carries deoxygenated blood to the lungs, and the venae cavae carry deoxygenated blood to the right atrium.
Q22. Which chamber of the heart has the thickest muscular wall?
The left ventricle has the thickest muscular wall because it must pump oxygenated blood to the entire body at high pressure. The right ventricle only pumps blood to the lungs, which requires less force. The atria have thinner walls.
Q23. The tiny blood vessels that connect arteries and veins are called:
Capillaries are tiny blood vessels that connect arteries and veins. They have very thin walls (one cell thick) and are the site of exchange of oxygen, carbon dioxide, nutrients, and waste products between blood and tissues. Arterioles and venules are smaller branches, and sinusoids are a type of capillary.
Q24. Which of the following correctly describes the path of blood from the heart to the lungs and back?
The correct pulmonary circulation path is: Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium. This is the pathway blood takes to get oxygenated. The other options have incorrect vessels or chambers.
Q25. The structure that prevents backflow of blood in veins is:
Veins have valves that prevent the backflow of blood, especially in the limbs where blood must flow against gravity. Arteries do not have valves (except the semilunar valves in the heart). Thick walls and elasticity are characteristics of arteries.
Q26. The normal resting heart rate per minute for a healthy adult human is approximately:
The normal resting heart rate for a healthy adult is about 60-100 beats per minute. Athletes may have lower rates, and children have higher rates. The other options are either too low or too high for a normal adult at rest.
Q27. The liquid part of blood that makes up about 55% of blood volume is called:
Plasma is the liquid part of blood, making up about 55% of blood volume. It is mostly water and contains dissolved proteins, hormones, nutrients, and waste products. Cytoplasm is inside cells, lymph is a separate fluid, and serum is plasma without clotting factors.
Q28. Which of the following is not a formed element (cellular component) of blood?
Plasma is not a formed element; it is the liquid matrix of blood. Formed elements are the cellular components: red blood cells, white blood cells, and platelets. Plasma is the fluid in which these cells are suspended. It makes up about 55% of blood volume.
Q29. The blood circulation in which blood passes through the heart twice in one complete cycle is called:
Double circulation is the type of circulation in mammals and birds, where blood passes through the heart twice in one complete cycle (once for pulmonary circulation and once for systemic circulation). Single circulation is found in fish, open and closed refer to the type of circulatory system.
Q30. In the human heart, the bicuspid (mitral) valve is located between:
The bicuspid (mitral) valve is located between the left atrium and the left ventricle. It prevents backflow of blood into the left atrium when the left ventricle contracts. The tricuspid valve is on the right side, and semilunar valves are at the exits of ventricles.
Q31. The semilunar valves are located at the bases of:
Semilunar valves are located at the bases of the pulmonary artery and the aorta. They prevent blood from flowing back into the ventricles after contraction. The atrioventricular valves (tricuspid and bicuspid) are between atria and ventricles.
Q32. Which of the following statements about capillaries is correct?
Capillaries are the sites of exchange of oxygen, carbon dioxide, nutrients, and waste products between blood and tissues. Their walls are very thin (one cell layer), allowing diffusion. They do not have thick walls, blood pressure is low, and they carry both oxygenated and deoxygenated blood.
Q33. The blood vessel that carries oxygenated blood from the left ventricle to all parts of the body is:
The aorta carries oxygenated blood from the left ventricle to all parts of the body. It is the largest artery. The pulmonary artery carries deoxygenated blood to the lungs, the pulmonary vein brings oxygenated blood to the heart, and the superior vena cava brings deoxygenated blood to the heart.
Q34. The total amount of blood in an average adult human body is approximately:
An average adult human body contains about 5-6 liters of blood. This varies with body size and sex. The other options are incorrect. Blood volume is about 7-8% of body weight.
Q35. The scientist who discovered that blood circulates and proved that veins have one-way valves was:
William Harvey discovered that blood circulates and demonstrated that veins have one-way valves. He published his findings in 1628, overturning earlier beliefs. Galen had incorrect ideas, Vesalius studied anatomy, and Malpighi discovered capillaries.
Q36. Which of the following is a correct difference between veins and arteries regarding the direction of blood flow?
Arteries carry blood away from the heart to the body tissues, while veins carry blood from the body tissues back to the heart. This is the fundamental directional difference. The other options are incorrect.
Q37. The blood vessel that carries deoxygenated blood from the lower part of the body to the right atrium is:
The inferior vena cava carries deoxygenated blood from the lower part of the body (legs, abdomen) to the right atrium. The superior vena cava carries blood from the upper body. The pulmonary vein carries oxygenated blood, and the aorta carries blood away from the heart.
Q38. The number of times the human heart beats in one minute on average is called:
The number of heartbeats per minute is called the pulse rate (or heart rate). Blood pressure is the force of blood against artery walls, cardiac output is the volume pumped per minute, and stroke volume is the volume pumped per beat. Pulse rate is the correct term.
Q39. The red color of human blood is due to:
The red color of human blood is due to the presence of iron in hemoglobin. Hemoglobin is a protein that binds oxygen. Hemocyanin (containing copper) gives blue color to some invertebrates, and chlorophyll (containing magnesium) is green.
Q40. Which of the following animals has colorless blood?
Cockroaches (and most insects) have colorless blood (hemolymph) because it does not contain hemoglobin or red blood cells. Human, dog, and fish blood is red due to hemoglobin. Insects transport oxygen through tracheae, not through blood.
Q41. The structure in the heart that prevents the mixing of oxygenated and deoxygenated blood is:
The septum is the muscular wall that separates the left and right sides of the heart, preventing oxygenated and deoxygenated blood from mixing. Valves control blood flow between chambers, the pericardium is the outer sac, and papillary muscles are attached to valves.
Q42. The blood pressure in arteries is highest during:
Blood pressure is highest during systole, when the ventricles contract and pump blood into the arteries. This is the systolic pressure (the higher number in a blood pressure reading). Diastole is the relaxation phase with lower pressure.
Q43. Which of the following statements about the pulmonary artery is correct?
The pulmonary artery is the only artery that carries deoxygenated blood. It carries blood from the right ventricle to the lungs for oxygenation. It does not carry oxygenated blood, does not carry blood from lungs to heart, and does not have valves like veins.
Q44. The hormone that stimulates red blood cell production is:
Erythropoietin (EPO) is a hormone produced by the kidneys that stimulates the bone marrow to produce red blood cells. Insulin regulates blood sugar, adrenaline is the “fight or flight” hormone, and thyroxine regulates metabolism.
Q45. Which of the following correctly matches the blood vessel with its characteristic?
Capillaries have walls that are only one cell thick and do not have valves. Arteries have thick walls and no valves (except semilunar valves in the heart), veins have thin walls and valves, and arteries do not always carry deoxygenated blood (pulmonary artery is an exception).
Q46. The volume of blood pumped by each ventricle in one beat is called:
Stroke volume is the volume of blood pumped by each ventricle in one heartbeat. Cardiac output is the total volume per minute (stroke volume × heart rate). Heart rate is beats per minute, and blood volume is total blood in the body. Stroke volume is the correct term.
Q47. The outermost layer that protects the heart and reduces friction is called:
The pericardium is the double-layered sac that surrounds the heart, protecting it and reducing friction during beating. The myocardium is the muscular layer, the endocardium is the inner lining, and the epicardium is the outer layer of the heart wall. The pericardium is the correct answer.
Q48. The blood cells that contain a nucleus in humans are:
White blood cells (WBCs) are the only blood cells that contain a nucleus in humans. Red blood cells lose their nucleus during maturation to make space for hemoglobin, and platelets are cell fragments without a nucleus. WBCs are the correct answer.
Q49. The pathway of systemic circulation is:
Systemic circulation is the pathway of oxygenated blood from the left ventricle through the aorta to body tissues, and deoxygenated blood returning via the venae cavae to the right atrium. Option B describes pulmonary circulation. The other options are incorrect.
Q50. The reason why the walls of arteries are thicker than veins is:
Arteries have thicker walls than veins because blood flows at higher pressure in arteries. The thick, elastic walls of arteries can withstand the high pressure generated by the heart’s pumping. Veins have thinner walls and lower pressure. Valves are not in arteries.