Free Circulation MCQs with Answers
695 Circulation MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The circulatory system covers the chambers, valves and conducting pathway of the human heart, along with the cardiac cycle and control of heartbeat. It compares arteries, veins and capillaries by structure and function, and explains how the lymphatic system returns tissue fluid, transports absorbed fats and supports immunity.
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Read the Circulation notesFree MDCAT chapter notes with key terms695 questions · page 25 of 35
- A. B-Capillary-Thin without muscle layer and wall two cell layers thick
- B. C-Vein-Thin walled and blood flows injerks/spurts
- C. D-Pulmonary vein-Takes oxygenated blood to heart, pO2 = 95 mmHg.
- D. A-Artery-Thick walled and blood flows evenly
Explanation: Two pulmonary veins from each lung transport the oxygenated blood to the left atrium.
Correct answer: D-Pulmonary vein-Takes oxygenated blood to heart, pO2 = 95 mmHg.- A. Basophil - Secretes serotonin, inflammatory response
- B. B-lymphocyte - Forms about 20% of blood cells involved in immune response
- C. Neutrophil - Most abundant blood cells, phagocytic
- D. Monocyte - The life span of 3 days, produces antibodies
Explanation: When observed under a microscope, basophils are a type of white blood cell that appear as large, irregularly shaped cells with…
Correct answer: Basophil - Secretes serotonin, inflammatory response- A. Albumin
- B. Serum amylase
- C. Globulin
- D. Fibrinogen
Explanation: Fibrinogen is a plasma protein that plays a crucial role in the coagulation (clotting) of blood.
Correct answer: Fibrinogen- A. 130/90 mm Hg is considered high and requires treatment
- B. 100/55 mm Hg is considered an ideal blood pressure
- C. 105/50 mm Hg makes one very active
- D. 190/110 mm Hg may harm vital organs like brain and kidney
Explanation: A blood pressure reading of 190/110 mm Hg is considered very high and falls into the category of severe hypertension.
Correct answer: 190/110 mm Hg may harm vital organs like brain and kidney- A. Complex QRS - one complete pulse
- B. Peak T initiation of total cardiac contraction
- C. Peak P and peak R together systolic and diastolic blood pressures
- D. Peak P initiation of left atrial contraction only
Explanation: The complex QRS on an ECG represents the depolarization (contraction) of the ventricles of the heart.
Correct answer: Complex QRS - one complete pulse- A. The flow of blood into the aorta will be slowed down
- B. The 'pacemaker' will stop working
- C. The blood will tend to flow back into the left atrium
- D. The flow of blood into the pulmonary artery will be reduced
Explanation: The tricuspid valve is located on the right side of the heart and prevents backflow of blood from the right ventricle into the right…
Correct answer: The flow of blood into the pulmonary artery will be reduced- A. (ii) and (iii)
- B. (iii) and (iv)
- C. (i) and (iv)
- D. (i) and (ii)
Explanation: (ii) Increase in red blood cell production: When individuals move to high altitudes, there is a decrease in the availability of oxygen.
Correct answer: (ii) and (iii)- A. (i) and (iv)
- B. (i) and (ii)
- C. (ii), (iii) and (iv)
- D. (iii), (iv) and (i)
Explanation: The correct statements (i)and (iv) are correct.(i) Arteries are thick-walled and have narrow lumen as compared to veins.
Correct answer: (i) and (iv)- A. P - start of systole
- B. T - end of diastole
- C. P - depolarization of the atria
- D. R - repolarisation of the ventricles
Explanation: The P wave in a standard ECG represents the depolarization of the atria. The atria are the upper chambers of the heart.
Correct answer: P - depolarization of the atria- A. Oxygen transport in the blood
- B. Clotting of blood
- C. Defence mechanisms of body
- D. Both B and C
Explanation: Yes, globulins contained in human blood plasma are primarily involved in the defence mechanisms of the body.
Correct answer: Both B and C- A. Plasma without proteins
- B. More WBCs and no RBCs
- C. More RBCs and less WBCs
- D. No plasma
Explanation: Lymph has more WBCs and no RBCs compared to blood. White blood cells (WBCs): WBCs are the main cells of the immune system.
Correct answer: More WBCs and no RBCs- A. Suction pull
- B. Pressure difference between the post caval and atrium
- C. Pushing open of the venous valves
- D. Both B and C
Explanation: Blood passes from the post caval to the diastolic right atrium of the heart due to the pressure difference between the two chambers.
Correct answer: Both B and C- A. Eosinophils
- B. Monocytes
- C. Neutrophils
- D. Basophils
Explanation: Basophils are concerned with the release of histamine and the natural anticoagulant heparin.
Correct answer: Basophils- A. Blood serum
- B. Sample from the thoracic duct of lymphatic system
- C. Whole blood from pulmonary vein
- D. All of these
Explanation: If a drop of each of blood, serum, and plasma is placed separately on four slides, the serum will not coagulate.Serum is the liquid part…
Correct answer: Blood serum- A. Octopus
- B. Hirudinaria
- C. Periplaneta
- D. All of these
Explanation: Periplaneta, commonly known as the American cockroach, does have an open circulatory system.
Correct answer: Periplaneta- A. Test tube containing calcium bicarbonate
- B. Normal test tube
- C. Test tube containing heparin
- D. Test tube containing sodium oxalate
Explanation: Calcium plays a very important role in blood clotting by converting prothrombin into thrombin.
Correct answer: Test tube containing calcium bicarbonate- A. Muscle fibers distributed throughout the heart walls
- B. Muscle fibers found only in the ventricle wall.
- C. Nerve fibers distributed in ventricles
- D. Nerve fibres found throughout the heart
Explanation: The Bundle of His is a network of the muscle fibers found in the wall of ventricles which transmits the electrical impulses from AV node…
Correct answer: Muscle fibers found only in the ventricle wall.- A. WBC+ proteins
- B. Blood - RBCs and some proteins
- C. RBCs + WBCs + plasma
- D. RBCs + proteins + platelets
Explanation: Lymph is a fluid that circulates through the lymphatic system. It contains various components, including white blood cells (WBCs) and…
Correct answer: WBC+ proteins- A. Purkinje fibres
- B. Papillary muscles
- C. AV node
- D. SA node
Explanation: The sinoatrial node (SA) node, present in the upper posterior wall of the right atrium.
Correct answer: SA node- A. Potassium
- B. Magnesium
- C. Calcium
- D. Sodium
Explanation: Blood consists of a watery fluid called plasma. Plasma is a faint yellow, slightly alkaline, viscous fluid.
Correct answer: Sodium