If a person's kidneys stop working, his blood is filtered through an artificial kidney, otherwise he cannot survive. This process is called:
- A.Excretion
- B.Dialysis
- C.Perspiration
- D.Expulsion
Correct answer
Explanation
The correct answer is B, Dialysis. Haemodialysis uses a machine called an artificial kidney to clean the blood of a patient whose kidneys have failed. Blood is drawn from the patient, mixed with an anticoagulant such as heparin so that it does not clot, and passed through fine tubes with a semi-permeable lining that sit in a dialysing fluid. Waste products such as urea pass out through the lining into the fluid, and the cleaned blood is returned to the body through a vein. A person with complete kidney failure needs this treatment regularly, often two or three times a week, unless a kidney transplant is done. The Dutch doctor Willem Kolff built the first working artificial kidney in 1943. Option A is wrong because excretion is the body's own natural removal of wastes, which healthy kidneys perform. Option C is wrong because perspiration means sweating through the skin. Option D is wrong because expulsion only means pushing something out; it is not the name of this treatment. Exam tip: the working unit of the kidney is the nephron, and the artificial kidney process is haemodialysis, which mainly removes urea.
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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