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 22 of 35
- A. atrioventricular bundle
- B. Purkinje system
- C. sinuatrial node
- D. atrioventricular node
Explanation: (c) : SA (sinoatrial) node is a specialized bundle of neurons located in the upper part of the right atrium of the heart.
Correct answer: sinuatrial node- A. SA node
- B. AV node
- C. Vagus nerve
- D. Cardiac nerve
Explanation: The SA node (SA stands for sinoatrial) is one of the major elements in the cardiac conduction system, the system that controls the heart…
Correct answer: SA node- A. no endothelium
- B. valves
- C. Thicker walls
- D. oxygenated blood.
Explanation: (c) : An artery has thick and more elastic wall but its lumen is narrow as compared to vein.
Correct answer: Thicker walls- A. Basophil
- B. Neutrophil
- C. Lymphocyte
- D. Eosinophil
Explanation: (c) : Agranulocytes are leucocytes that lack granules in the cytoplasm. They are formed in spleen and lymph nodes and bone marrow.
Correct answer: Lymphocyte- A. between 2 to 3 months
- B. more than 4 months
- C. less than 10 days
- D. between 20 to 30 days
Explanation: (c) : WBCs (also called leucocytes) are rounded or irregular colourless cells with a nucleus.
Correct answer: less than 10 days- A. sinoatrial node (SAN)
- B. atrioventricular node (AVN)
- C. Purkinje fibres
- D. papillary muscle.
Explanation: AV (atrioventricular) node is a mass of modified heart muscle situated in the lower middle part of the right atrium.
Correct answer: atrioventricular node (AVN)- A. endothelium, connective tissue and muscle fibres
- B. endothelium and muscle fibres
- C. endothelium and connective tissue
- D. endothelium only.
Explanation: (d) : The wall of capillaries is very thin (usually less than one micron) and have numerous minute pores and made up of only endothelium.
Correct answer: endothelium only.- A. Bilirubin
- B. Iron
- C. Biliverdin
- D. Both A and B
Explanation: The haemoglobin is broken down into haem i.e., iron and globin protein which is then converted into yellowish substance bilirubin which is…
Correct answer: Bilirubin- A. Evaporation
- B. Transpiration pull
- C. Guttation
- D. Wilting
Explanation: Answer is "Transpiration pull"Explanation: The main force that draws water from the soil for plant is caused by a process called…
Correct answer: Transpiration pull- A. Increases
- B. No effect
- C. Decreases
- D. Stops
Explanation: Answer is "Increases"When sugar level rises i.e. solute concentration increases of water potential decreases- and the guard cells become…
Correct answer: Increases- A. Xylem
- B. Endodermis
- C. Epidermis
- D. Pericycle
Explanation: Answer is "Xylem"Explanation: Phloem is generally found on outer side of xylem,which is responsible for transporting water and minerals in…
Correct answer: Xylem- A. Naturally induced active immunity
- B. Artificially induced active immunity
- C. Active immunity
- D. Passive immunity
Explanation: "The explanation for this question will be added soon!".
Correct answer: Naturally induced active immunity- A. Cell-mediated response
- B. Humeral immune response
- C. Active immunity
- D. Passive immunity
Explanation: "The explanation for this question will be added soon!".
Correct answer: Cell-mediated response- A. 60-70%
- B. 1-2%
- C. 80-90%
- D. 5-7%
Explanation: Answer is "80-90%"Explanation: The degree of opening of stomatal pores also affects the rate of transpiration.
Correct answer: 80-90%- A. Decrease in turgidity of guard cells
- B. Radial orientation of cellulose microfibrils in the cell wall of guard cells
- C. Longitudinal orientation of cellulose microfibrils in the cell wall of guard cells
- D. Contraction of outer wall of guard cells
Explanation: When turgidity increases within the two guard cells flanking each stomatal aperture or pore, the thin outer wall bulge out and force the…
Correct answer: Radial orientation of cellulose microfibrils in the cell wall of guard cells- A. Passive absorption
- B. Active absorption
- C. Increase in transpiration
- D. Low osmotic potential in soil
Explanation: Root pressure is positive pressure that develops in the xylem sap of the root of some plants.
Correct answer: Active absorption437. A column of water within xylem vessels of tall trees does not break under its weight because of:
- A. Lignification of xylem vessels
- B. Positive root pressure
- C. Dissolved sugars in water
- D. Tensile strength of water
Explanation: Cohesion, adhesion and surface tension are the forces responsible for movement of water up the tracheary elements.
Correct answer: Tensile strength of water- A. The shoot and root die together
- B. Neither root nor shoot will die
- C. The shoot dies first
- D. The root dies first
Explanation: In girdling or ringing experiments, a ring of bark is cut from the stem. It also removes phloem.
Correct answer: The root dies first- A. Pushing it upward
- B. Pushing and pulling it, respectively
- C. Pulling it upward
- D. Pulling and pushing it, respectively
Explanation: The transpiration process, pulls water upwards with the help of cohesion and adhesion properties of water molecules.
Correct answer: Pulling and pushing it, respectively- A. Starch hydrolysis
- B. Guard cell photosynthesis
- C. Transpiration
- D. Potassium influx and efflux
Explanation: According to this theory, K + ion enter and accumulate in guard cells during daytime, causing opening of stomata and during night, K +…
Correct answer: Potassium influx and efflux