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 6 of 35
- A. Between right atrium and right ventricle
- B. Between left atrium and left ventricle
- C. At base of pulmonary artery
- D. At base of aorta
Explanation: The tricuspid valve lies between the right atrium and right ventricle and prevents blood from flowing back into the atrium during…
Correct answer: Between right atrium and right ventricle- A. Posterior
- B. Anterior
- C. Lateral
- D. All possible
Explanation: In the usual anatomical description, blood enters the heart from the posterior side through the atria and leaves through vessels located…
Correct answer: Posterior- A. Sinus venosus
- B. Right atrium
- C. Left atrium
- D. Conus arteriosus
Explanation: In fish, blood returning from body tissues first enters the sinus venosus, which passes it to the atrium and then the ventricle.
Correct answer: Sinus venosus- A. Hemoglobin
- B. Enzymes
- C. Salts
- D. Other proteins
Explanation: About 95% of the dry cytoplasmic content of a red blood cell is hemoglobin, the iron-containing protein that binds and transports oxygen.
Correct answer: Hemoglobin- A. Spleen
- B. Kidney
- C. Liver
- D. Pancreas
Explanation: The spleen filters blood and its macrophages remove old or damaged RBCs, recycling their iron and other components.
Correct answer: Spleen- A. Movement of viscera
- B. Breathing movements
- C. Valves
- D. All of these
Explanation: Lymph is moved by skeletal-muscle and visceral movements and by pressure changes during breathing, while valves prevent its backward flow…
Correct answer: All of these- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Each capillary is extremely narrow, there are millions of them, and this wide distribution forces the blood to spread out, slowing it…
Correct answer: Option D- A. Oedema
- B. Leukaemia
- C. Thalassemia
- D. Atherosclerosis
Explanation: Thalassemia is a genetic disorder that affects the body's ability to produce normal haemoglobin, leading to reduced levels of haemoglobin…
Correct answer: Thalassemia- A. Blood flow in the brachial artery becomes turbulent, creating audible sounds
- B. The diameter of the lumen of the brachial artery gets minimized
- C. The pressure in the cuff is greater than the pressure in the artery
- D. Enough air pressure is pumped into the cuff to close the artery
Explanation: During blood pressure measurement, sounds are heard as blood starts to flow through the compressed artery and becomes turbulent.
Correct answer: Blood flow in the brachial artery becomes turbulent, creating audible sounds- A. Prevent collapse of these blood vessels
- B. Reduce friction within these blood vessels
- C. Anchor these vessels with surrounding tissues
- D. Prevent too much pressure exerted on their walls
Explanation: The thick elastic layer in the walls of large arteries, such as the aorta, is crucial for maintaining blood pressure and ensuring…
Correct answer: Prevent too much pressure exerted on their walls- A. Capillaries lack valves
- B. Capillaries have one cell thick walls
- C. Resistance in blood flow is negligible in capillaries
- D. Total cross-sectional area of the capillaries is greater than other vessels
Explanation: The correct answer is that the rate of blood flow is slowest in capillaries because the total cross-sectional area of the capillaries is…
Correct answer: Total cross-sectional area of the capillaries is greater than other vessels- A. Normal
- B. Hypotension
- C. Mild hypertension
- D. Hypertension requiring treatment
Explanation: The reading of 176/105 mm Hg indicates stage 2 hypertension, which is characterized by a systolic pressure of 160 mm Hg or higher and/or a…
Correct answer: Hypertension requiring treatment- A. option A
- B. Option B
- C. Option C
- D. Option D
Explanation: The marked cells are neutrophils because they have multilobed nucleus. Neutrophils are white blood cells with a multi-lobed nucleusSo A is…
Correct answer: option A- A. Absence of blood capillaries
- B. Regulation of blood pressure
- C. Absence of respiratory pigments
- D. Flow of haemolymph in cavities
Explanation: In a closed circulatory system, blood circulates within a network of vessels, allowing for efficient regulation of blood pressure.
Correct answer: Regulation of blood pressure- A. Haemorrhage
- B. Atherosclerosis
- C. Arteriosclerosis
- D. Myocardial infarction
Explanation: The correct answer is haemorrhage. A haemorrhage is the medical term for the escape of blood from a ruptured blood vessel.
Correct answer: Haemorrhage- A. 24o
- B. 90o
- C. 144o
- D. 270o
Explanation: To determine the angle of the sector for blood group B, calculate it using the formula: (Number of students with blood group B / Total…
Correct answer: 144o- A. Aorta
- B. Veins
- C. Arteries
- D. Capillaries
Explanation: Blood pressure is the pressure exerted by the blood on the walls of the blood vessels.
Correct answer: Aorta- A. 10
- B. 20
- C. 25
- D. 55
- E. 75
Explanation: Albumins constitute around 75% of the plasma proteins. They are the smallest of the plasma proteins and play an important role in…
Correct answer: 75- A. Non-nucleated
- B. In deficiency, cancer is caused
- C. Manufactured in thymus
- D. Can squeeze through blood capillaries
Explanation: The correct answer is that WBCs can squeeze through blood capillaries. This is due to their amoeboid shape and the process known as…
Correct answer: Can squeeze through blood capillaries- A. Spleen
- B. Red bone marrow
- C. Kidney
- D. Liver
Explanation: Erythropoiesis is the formation of red blood cells (erythrocytes) which occurs in the red bone arrow.
Correct answer: Red bone marrow