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 24 of 35
- A. Stomatal opening
- B. Stomatal closing
- C. Stomatal formation
- D. Stomatal activity
Explanation: There is evidence to believe that besides organic acids the turgidity of guard cells is usually controlled by K + , Cl - and H + .
Correct answer: Stomatal closing- A. Water transformations
- B. Transpiration
- C. Thermoperiodism
- D. Translocation
Explanation: In terrestrial habitats, temperature and rainfall conditions are influenced by transpiration.
Correct answer: Transpiration- A. Hygrometer
- B. Potometer
- C. Auxanometer
- D. Tensiometer/Barometer
Explanation: Under normal circumstances, the rate of water uptake gives a measure of the rate of transpiration.
Correct answer: Potometer- A. Turgor pressure
- B. Wall pressure
- C. Diffusion pressure deficit
- D. Incipient plasmolysis
Explanation: Water movement between cells is due to DPD. If a cell is placed in pure water it shows endosmosis and as a result, water enters into the…
Correct answer: Diffusion pressure deficit- A. Capillarity
- B. Role of atmospheric pressure
- C. Pulsating action of living cell
- D. Transpiration pull and cohesion theory of Dixon and Jolly
Explanation: Transpiration pull cohesion theory for ascent of sap in trees is most widely accepted. This concept was proposed by Dixon and Jolly, 1884.
Correct answer: Transpiration pull and cohesion theory of Dixon and Jolly- A. Gravitational water
- B. Capillary water
- C. Hygroscopic water
- D. Combined water
Explanation: In soil, the water available for root absorption is capillary water, which is a type of soil water.
Correct answer: Capillary water- A. Sieve cells
- B. Sieve tube elements
- C. Xylem vessel system
- D. Xylem and phloem
Explanation: The principal pathway of water translocation in angiosperms is xylem vessel system.
Correct answer: Xylem vessel system- A. Diffusion
- B. Imbibition
- C. Osmosis
- D. Diffusion pressure deficit
Explanation: A bottle filled with previously moistened mustard seeds and water was screw-capped tightly and kept in a corner.
Correct answer: Imbibition- A. Xylem
- B. Phloem
- C. Sieve tubes
- D. None of the above
Explanation: Minerals absorbed by roots move to the leaf through xylem. Xylem plays an important role in conduction of water.
Correct answer: Xylem- A. Circadian rhythm
- B. Genetic clock
- C. Pressure of gases inside the leaves
- D. Turgor pressure of guard cells.
Explanation: The pressure that develops in a cell due to osmotic diffusion of water inside it, is called turgor pressure.
Correct answer: Turgor pressure of guard cells.- A. Reduced photosynthesis
- B. Reduced transpiration
- C. Reduced respiration
- D. Killing of plants
Explanation: Phenyl mercuric acetate (PMA) results in reduced transpiration. PMA is an antitranspirant.
Correct answer: Reduced photosynthesis- A. Good soil moisture
- B. High wind velocity
- C. Dry environment
- D. High atmospheric humidity
Explanation: Transpiration is least in high atmospheric humidity. The rate of transpiration is directly proportional to the saturation deficit.
Correct answer: High atmospheric humidity- A. Ψ s + O.P
- B. Ψ s = T.P
- C. Ψ p + Ψ w
- D. Ψ s + Ψ p
Explanation: Water potential is the difference in the free energy or chemical potential per unit molal volume of water in a system and that of pure…
Correct answer: Ψ s + Ψ p- A. Only (1)
- B. (1), (3) and (4)
- C. (2) and (3)
- D. (1) (2) (3) (4)
Explanation: Red blood cells of adult humans do not have cell organelles including nucleus, Golgi bodies, mitochondria, ribosomes, etc.
Correct answer: (1) (2) (3) (4)- A. Stomach
- B. Kidneys
- C. Intestine
- D. Heart
Explanation: Blood enters the liver from two sources. From the hepatic artery, it gets oxygenated blood and from the hepatic portal vein, it receives…
Correct answer: Intestine- A. Hepatic Vein
- B. Hepatic Portal Vein
- C. Renal Vein
- D. Dorsal Aorta
Explanation: Hepatic vein carries largest amount of urea. Urea is produced in liver.
Correct answer: Hepatic Vein- A. Whale
- B. Shark
- C. Frog
- D. Lizard
Explanation: Whale is a mammal and in mammals, two separate circulatory pathways are found - systemic circulation and pulmonary circulation.
Correct answer: Whale- A. Systole of the left ventricle
- B. Diastole of the right atrium
- C. Systole of the left atrium
- D. Diastole of the right ventricle.
Explanation: During systole, the heart muscle contracts, and blood is pumped out of the left ventricle into the aorta, which is the largest artery in…
Correct answer: Systole of the left ventricle- A. C -Vena cava- takes blood from body parts to right auricle, pCO 2 = 45 mm Hg
- B. D-Dorsal aorta- takes blood from heart to body parts, pO 2 = 95 mm Hg
- C. A-Pulmonary vein - takes impure blood from body parts, pO 2 = 60 mm Hg
- D. B-Pulmonary artery takes blood from heart to lungs, pO2 = 90 mm Hg
Explanation: C -Vena cava- takes blood from body parts to right auricle, pCO 2 = 45 mm Hg.
Correct answer: C -Vena cava- takes blood from body parts to right auricle, pCO 2 = 45 mm Hg- A. Beginning of the systole
- B. End of systole
- C. Contraction of both the atria
- D. Initiation of the ventricular contraction
Explanation: P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria.
Correct answer: Contraction of both the atria