The only vein that carries oxygenated blood is called:
- A.Cystic vein
- B.Pulmonary vein
- C.Hepatic portal vein
- D.Cardiac vein
Correct answer
Explanation
The correct answer is B, Pulmonary vein. Veins usually carry blood low in oxygen back to the heart, but the pulmonary veins are the exception. After blood picks up oxygen in the lungs, four pulmonary veins, two from each lung, bring this oxygen-rich blood to the left atrium of the heart. From there it passes to the left ventricle, which pumps it to the whole body through the aorta. The mirror-image fact is asked just as often: the pulmonary artery is the only artery that carries deoxygenated blood, taking it from the right ventricle to the lungs. So the rule is that arteries carry blood away from the heart and veins carry it towards the heart, whatever its oxygen level. Option A is wrong because the cystic vein drains the gall bladder. Option C is wrong because the hepatic portal vein carries nutrient-rich but oxygen-poor blood from the intestines to the liver. Option D is wrong because the cardiac veins drain used blood from the heart muscle into the right atrium. Exam tip: pulmonary vein, the only vein with oxygenated blood; pulmonary artery, the only artery with deoxygenated blood.
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
Show answer
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.
Show answer
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
Show answer
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.
Show answer
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.
Show answer
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.
Read the full explanation →