The oxygenated blood from the lungs is received by the
- A.left auricle
- B.left ventricle
- C.right auricle
- D.right ventricle
Correct answer
Explanation
The correct answer is A, left auricle. Oxygen-rich blood from the lungs returns through the pulmonary veins into the left auricle (left atrium) of the heart.
The human heart has four chambers: two upper auricles (atria) that receive blood and two lower ventricles that pump it out. In the pulmonary circuit, blood picks up oxygen in the lungs and comes back through the pulmonary veins to the left auricle. It then passes through the bicuspid (mitral) valve into the left ventricle, which pumps it into the aorta for the whole body. The pulmonary veins are the only veins that carry oxygenated blood.
B is wrong because the left ventricle receives blood from the left auricle, not directly from the lungs, and pumps it into the aorta.
C is wrong because the right auricle receives deoxygenated blood from the body through the venae cavae.
D is wrong because the right ventricle pumps deoxygenated blood to the lungs through the pulmonary artery.
Exam tip: pulmonary veins carry oxygenated blood to the left auricle; the pulmonary artery carries deoxygenated blood from the right ventricle.
Practice Questions
View allThe fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
Read the full explanation →Which one of the following statements is correct?
- A.Urea is produced in liver.
- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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Liver cells turn the toxic ammonia released from the breakdown of amino acids into urea through the ornithine cycle, also called the urea cycle.
Read the full explanation →Which one of the following is the correct sequence of passage of light in a compound microscope?
- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
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Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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It binds oxygen at its iron-containing haem groups and carries some carbon dioxide on its protein chains. Each haemoglobin molecule has four polypeptide chains and four haem groups, and each haem iron can hold one oxygen molecule, forming oxyhaemoglobin in the lungs.
Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
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